Bioplastics: An Alternative to Petrochemical Plastics in Prosthetics

A proposal to prosthetic companies and plastic manufacturers to utilize polyhydroxyalkanoate in their products

Tag words: bioplastic; PHA; polyhydroxyalkanoate; prosthetic; thermoplastics; biodegradation; petrochemicals; petroleum; plastic

Authors: Farrah Khan, Karissa Tuason, Anthony Sena and Julie M. Fagan, Ph.D.

Summary:

Most prosthetic manufacturing companies use crude oils that are expensive and not environmentally friendly. The use of natural materials is a more efficient alternative in creating prosthetics today. Methods of producing a cost-effective, functional, and environmentally friendly material involves utilizing polyhydroxyalkanoate (PHA) that is derived from biological processes. Incorporating this biopolymer into prosthetics will be a step forward for the prosthetic and plastic industries. By contacting a manufacturing company and proposing these alternative methods, the extraction of hazardous crude oils, and the future cost of prosthetics could be reduced.

Video Link: https://www.youtube.com/watch?v=W_DV0l2mgBE

The Issue: Plastic Alternatives in Prosthetic Devices Introduction (KT)

Prosthetics are an important part of the medical industry today, and given the number of people in the US, 1.6 million people that have lost limbs, their lives can be improved by the prosthetic industry (1). Therefore, the quality of the prosthetic, which includes the methods and materials used to make it, is of prime importance.

Currently, plastics incorporated into prosthetics are not environmentally friendly, and their disposal, and manufacturing contribute to pollution accumulating in the world. These plastics are petrochemical plastics, which are manufactured by refining crude oil and natural gas that are extracted from below the Earth's surface. Replacing these plastics with an environmentally friendly alternative will greatly benefit both the producers and consumers. One such alternative is the use of bioplastics, which, in essence, are plastics that are produced by biochemical reactions within the cell.

Background and History (KT)

From Ancient Egypt, two toes, made of wood and leather, were found to be the oldest prosthetics ever made. Not only did they help medically by assisting with balance, they were also found to make wearing sandals more comfortable (2). During the Roman Empire, bronze and iron were used to reinforce prosthetic devices for greater durability. Later in the Middle Ages, peg legs and hooks for hands, famous in pirate lore, entered the prosthetic world, but they were affordable only to the wealthy. At the time, most of the prosthetics were worn for decorative purposes due to their limited functionalities. This was later changed during the Renaissance when the addition of a locking mechanism to the prosthetic allowed it to be set into different positions. Also, the use of leather, paper, and glue reduced the amount of metal incorporated into the prosthetic, making it lighter. In addition to the improvement of the prosthetic, the basic amputation procedures improved as well. By the 19th century, prosthetic limbs were further improved by replacing steel with aluminum; they also began to resemble the amputated limbs. Wars in the 18th and 19th centuries led to an increase in amputees and forced advancements in the production of prosthetics and the amputation process. Today, prosthetics are lighter and more functional by incorporating, plastic and electrical devices, such as computer chips (3).

Prosthetic Components (KT)

A prosthetic limb is usually composed of two parts: the prosthesis and the socket that connects the prosthesis to the residual limb. The prosthesis is the part of the prosthetic that will replace the lost limb. It can be made of a variety of materials depending on the prosthetic type and the preference of the manufacturer. The socket is made of materials that allow for flexibility and durability, most commonly plastic. They are custom made to fit each individual in order to distribute the weight of the prosthesis evenly, which requires measuring the residual limb in order to make a mold. Plastic composes most of the socket and prosthesis together, making it a vital material in prosthetic production.

Production of Prosthetics (FK)

The process of making, fitting, adjusting, and finalizing a prosthetic device is a long and complex procedure, designed to create the most efficient prosthetic through resourceful and cost- effective manufacturing. The process in and of itself is not complicated, but without precision, it can lead to a faulty prototype, thus ultimately creating a nonfunctional prosthetic. While visiting Hanger, Inc., a company located in Edison, New Jersey that custom-builds prosthetic parts for their patients, the notion of efficiency and using the resources at hand to their full extent was a core principle held in high regard across the industry. A mold, as seen in Figure 1, was shown of an incorrectly made prosthetic that ultimately had to be discarded, requiring the workers to start again and use up extra material. Figure 1. An unusable prosthetic socket. Picture taken in Hanger Inc.

Creating prosthetics demands skill and precision while working under a set time with a fixed amount of resources. Any fault in these areas would be a disadvantage to the companies producing prosthetics, as well as to the environment that suffers under the detrimental consequences of discarding unusable prosthetics, a topic to be further discussed.

The first step in creating a prosthetic is making a plaster cast of the area the prosthetic will be fitted on the patient, or the residual limb. The prosthetist will commonly use a digital reading or use impressions (done by hand) first to make accurate measures of the residual limb. These measurements will naturally change over time, as the patient will undergo changes in volume and shape (4), therefore each fitting is extremely important in precision so as to maintain comfort and accuracy of the prosthetic. This means the prosthetic will be “outgrown” and will need to be altered several times, and thus initial measurements are important as they will later be calibrated with future fittings. Using these data, the prosthetist will then proceed to create a plaster cast. From there, an exact copy of the plaster cast is made, called a “positive mold” (5).

The positive mold is used as a template for the socket. A clear thermoplastic sheet is heated at high temperatures in an oven, which is then placed over the positive mold perfectly by using a vacuum. The sheet collapses about the mold when the air is sucked out of the vacuform, and thus successfully creating the test socket for the prosthetic (4). This is where fittings happen again, checking that the socket does indeed fit comfortably around the patient’s residual limb, and ensuring there is no instability or any pressure issues. If recalibrations are necessary, the test socket is merely reheated and reshaped until it fits to the patient’s new measurements. This is the essential purpose of why thermoplastic is used, as the reheating and readjustments are an integral part of the prosthetic-making process, therefore a malleable, efficient, and reheatable plastic is absolutely necessary.

Different types of plastics can then be used to fit the permanent mold such as polyethylene, polypropylene, acrylics, and polyurethane. Similar to the process of when the test socket was created, the plastic is used to cover the mold and the air is sucked out by a vacuum.

Figure 2. Process of Making a Prosthetic Socket (5).

The illustration above demonstrates the pieces involved in creating a fully functional prosthetic limb. Soft-foam parts and sometimes plastic are used to create the pads and lining, then the previous steps are repeated to ensure proper fitting. Sometimes, injection molding and extrusion will also be used as methods to form plastic pieces. The former involves forcing liquidized plastic through a mold and allowing it to cool until it creates the intended shape; the latter involves pulling plastic through a specific-shaped die (5). Both methods are shown in Figures 3 and 4 below. Figure 3. Diagram of Injection Molding (6).

Figure 4. Diagram of Extrusion (7).

In addition, the pylon structure is generally made from either aluminum or titanium, which are also cast through a die by forcing the liquidized metal through a steel die into the intended mold. Lastly, the feet are typically made from wood, and then later sawed and chiseled to the appropriate shape, using materials such as hickory, willow, and maple, among others. (5). In terms of appearance, a cover and a sock, which closely resembles the flesh tone of the patient, is placed over the prosthetic to make it closer to an actual limb in shape and color. This cover material is made from polyurethane foam. An illustration of a completed prosthetic limb and its cover is shown in Figure 5 below. Figure 5. A completed prosthetic leg and cover (5).

The prosthetic industry and the overall treatment of prosthesis relies heavily on the use of proper materials, without which, it would not have progressed as rapidly, leaving those in need of treatment with less opportunity to live as functionally and independently as they once did. The key material that allows for this progression is plastic.

What is plastic? (KT)

Plastic, as IUPAC defines it, is a “generic term used in the case of polymeric material that may contain other substances to improve performance and/or reduce costs.” The more preferred term is polymer which is a “substance composed of macromolecules” (8). They are classified by their composition, method of synthesis, and other properties such as biodegradability, molding properties, and sources from which they are derived. Their composition specifies the polymer’s structure, such as which monomers make up its backbone and side-chains, and how the monomers are connected. A polymer’s method of synthesis refers to whether it was made by condensation or addition reactions. The sources from which they are derived refers to whether they are synthetic or natural.

History of Plastic (KT)

The production and use of plastics began in the 19 th century with the invention of Parkesine plastic and casein plastic. Parkesine plastic is made from dissolving cellulose nitrate, and casein plastic is made from reacting casein with formaldehyde, which was used as insulation and a moldable substance. Modern plastics were invented in the early 20 th century with the development of thermoplastics from cellulose acetate, polyethylene, polystyrene, and so on. These plastics were expensive during this time and weren’t in high demand until World War II. The shortage of supplies caused by the war allowed plastics to be used as a substitute material. This sudden increased demand for plastics resulted in the research for its production and the development of factories to produce a greater variety, which ultimately reduced its cost. (9)

Sources of Plastic: Oil Companies (KT)

Most of the plastics used today are derived from petroleum found under the Earth’s surface where ancient algae were buried, and exposed to high temperature and pressure. Petroleum, a class of liquid that is composed of hydrocarbon mixtures, which includes crude oil and natural gas, are drilled from pockets underground by petroleum industries. Most of the oil used in the United States is imported from outside sources, as shown in Figure 6 below (10). However, the remaining oil produced in the U.S. is mainly extracted from seven regions: Marcellus, Ultica, Haynesville, Eagle Ford, Permian, Niobrara, and Bakken. (11)

Figure 6. Where the U.S. gets its oil (10).

Making Plastic (KT)

Extraction of crude oil or natural gas from the Earth begins with exploration where geologists study the landscape and outcroppings to locate possible pockets of petroleum. They check underneath the Earth’s surface using seismology, magnetometers, and gravimeters. Once these preliminary tests are performed, exploratory wells are drilled where the potential pockets are thought to be located. When a petroleum reserve is found, more wells are dug to increase the rate of extraction. An illustration of the components of an oil rig is shown in Figure 7 below. Secondary wells that pumps steam, water, or acid help regulate the pressure in the reservoir. This process is termed fracking. Once the oil is extracted, it is brought to an oil refinery (12). Figure 7. Common equipment used in ocean drilling rigs (13).

In an oil refinery, the crude oil is distilled into fractions of hydrocarbon chain mixtures. One of which, called naptha, is broken down into the monomers of common plastics through a process called cracking. These monomers are then moved into a polymerization reactor where they are linked together into chains. There are two types of polymerization reactions depending on the type of plastic being made: addition reactions and condensation reactions. In addition polymerization, the monomers are linked together without the loss of any atoms; conversely in condensation polymerization, the monomers are linked together with the loss of atoms in the form of water. Both reactions require a catalyst to speed up the reaction. The product is a paste- like resin where dyes, fillers, and other additives can be mixed in and then processed into microplastics called nurdles (14). These nurdles are then processed into usable plastic products, depending on which company is using the base materials.

Cost of plastic Process (FK)

The question that arises then is: what is the cost of processing and obtaining these materials? For crude oil extraction alone, the U.S. spends approximately $33.76 per barrel; this includes the lifting and finding costs shown in Figure 8 below (15). Lifting involves the utilization and maintenance of oil machinery, as well as the gas wells from which the oils are extracted. This cost at first is seemingly inconsequential, however considering that the U.S. used 191 million barrels of oil in the year 2010 alone (16), specifically for plastic products, it brings a total cost of $6.4 billion spent just on obtaining the basic materials. Furthermore, making the oil rigs that extract crude oil is a massive cost as well. Two common types of ships used are floaters and jackups; floaters can cost from $500 to $700 million each, and jackups can cost from $175 to $225 million each. This is solely in the production cost; it does not include maintenance or abandonment. (17) In addition to the cost of extracting crude oil is the production cost. One of the major costs of production is the handling of nurdles, which in the Katoen Navie international company, costs $1.5 million (18).

Figure 8. Cost for producing crude oil and natural gas in 2007-2009 (15).

All of these costs combined create a multibillion dollar industry, not just in the U.S., but internationally. The impact plastic production has had as a whole not only affects the economy, but the environment as well.

Plastics and the Environment (FK)

On April 20, 2010 in the Gulf of Mexico, the Deepwater Horizon, a drilling rig owned by BP that could drill 10,000 feet deep into the ocean, subsequently exploded and set the entire platform on fire, killing a total of 11 workers. Two days later, an oil leak was discovered near the explosion site and spread for 87 days, severely damaging, poisoning, and killing the aquatic life in the spill area. Fish were found with lesions and sores, shrimp were found with eyes and eye sockets missing, and dead newborn dolphins were found washed ashore, adding to a rapidly growing list of mutations and casualties due to the spill. While 4.6 million pounds of oil materials have reportedly been cleared as of 2013, the present day devastatio n left by its occurrence is unignorable. If crude oil can have this astronomical impact from a single spill, what happens when it is simply extracted? What are the health risks when people come in direct contact with crude oil?

Crude oil is an amalgam of organic compounds that are carcinogenic and toxic to wildlife and humans, and exposure to them can cause harmful and irreversible effects. The distillation of crude oil and petroleum releases gas which can cause birth defects in infants whose parent had come in contact with it. Crude oil also contains benzene, a compound known to cause leukemia by entering the cells and damaging DNA (19), and can decrease the white blood cell count so that the immune system is weakened, thus leaving the affected people more vulnerable to infections. The chemicals also include neurotoxins which can impact the brain, causing symptoms such as nausea, headaches, euphoria, dizziness, and blurred vision. These toxins are absorbed through the lungs and the skin.

Burning the petroleum used to make petro-based polymers produces massive amounts of carbon dioxide, and releases greenhouse gases into the atmosphere, adding to the already problematic concerns of global climate change. Furthermore, once the plastic products are made, their chemical structure does not allow them to be biodegraded. Thus, when they are discarded, they sit in landfills, and potentially increase the amount of harmful chemicals that spread into the earth. It is clear, then, that using crude oil as a plastic source is an environmentally dangerous pursuit that impacts not just the wildlife surrounding the extraction, but the people who come in contact with it. What you need, then, is an alternative that eliminates the harmful crude oil extraction process, is environmentally sound, and produces an equally functional plastic product.

The Alternative (AS)

The best alternative being used today is a type of natural thermoplastic that is formed within cells of living organisms termed bioplastics. There are a wide range of organisms that can produce a variety of such plastics. The appeal of working with bioplastics, as opposed to the common petroleum-based plastic, is the fact that they are biodegradable. The plastics in use today are made of polymers such as polystyrene or polypropylene, which remain in the environment for many years, and can become toxic to any living organism that it comes in contact with. Bioplastics do not have this issue because they are made from natural sources, and can therefore be easily broken down by processes already occurring in the environment.

The process of obtaining and producing bioplastics is less harmful to the environment than the extraction methods used for crude oils. Since bioplastics are not coming from within the earth, but rather from easily accessible organisms that live on it, the environmental hazards which are associated with crude oil extraction are of no consequence for bioplastic retrieval. Certain types of animals, plants, fungi, and bacteria are sources of bioplastic polymers due to the enzymatic reactions that occur within their cells. These polymers can come in the form of oils, waste products, storage molecules for later energy consumption, or many other possible materials. They can be mass produced either directly from bacterial sources or through bacterial intermediates. The latter, however, requires genetic modification of the bacteria to yield polymers normally produced by other organisms.

Each type of organism that is capable of making biopolymers for plastic has different benefits. Plants and animals are larger and easier to work with in terms of being able to easily visualize the organism that is being used; however, there would need to be facilities with a large amount of space to fit and sustain the organism in question. Bacteria and fungi, on the other hand, while microscopic and difficult to see, are easy to grow, maintain, and store in relatively small areas. An added benefit to working with microorganisms rather than plants and animals is that a large quantity of the organism can be used more readily to produce the desired polymer. While any of these methods for mass producing biopolymers are feasible, the decision on which type of organism to use depends upon the type of plastic that is being manufactured. In the case of finding a new bioplastic that can be a promising replacement for the petroleum-based plastics currently being utilized in most prosthetic limbs, a durable, flexible thermoplastic must be used.

One natural polymer that would be suitable for use in artificial limbs is polyhydroxyalkanoate, or PHA. PHA is a polymer that is naturally produced by a multitude of microorganisms for use as a stored carbon source. It has a generalized form as shown in the figure below, and a variable number of PHAs have been shown to exist, including polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), and various others. There have been many PHA-producing bacteria that have been found in the environment, and the number continues to grow. Most of the bacteria that have been found to produce PHA are hydrocarbon degrading bacteria. This is significant because various types of waste materials and pollutants can be used to feed into these bacterial cultures, yielding the biopolymers needed for biodegradable plastic fabrication (20); essentially killing two birds with one stone, environmentally speaking.

Figure 9. Structure of PHA (21).

PHA is considered a bioplastic because it is derived entirely from living microorganisms and is 100% biodegradable. In fact, it is the only bio-based polymer that can make such a claim; most if not all other marketed bioplastics are either not entirely made by living organisms, or are only partially biodegradable (21). Some other bioplastics such as polyethylene or polyvinyl chloride are produced by living organisms, but are not at all biodegradable. Polylactic acid and starch come close to being considered true bioplastics due to their organismal origins and biodegradability, but they fall short because they require non-biodegradable additives to improve their properties as functional plastics. The IUPAC has determined proper descriptions of what should be considered a bioplastic (bio-based polymer) and what is biodegradable: Bioplastic Biobased polymer derived from the biomass or issued from monomers derived from the biomass and which, at some stage in its processing into finished products, can be shaped by flow. Note 1: Bioplastic is generally used as the opposite of polymer derived from fossil resources. Note 2: Bioplastic is misleading because it suggests that any polymer derived from the biomass is environmentally friendly. Note 3: The use of the term “bioplastic” is discouraged. Use the expression “biobased polymer”. Note 4: A biobased polymer similar to a petrobased one does not imply any superiority with respect to the environment unless the comparison of respective life cycle assessments is favourable. Biodegradation (biorelated polymer) Degradation of a polymeric item due to cell-mediated phenomena [9]. Note 1: The definition given in [2] is misleading because a substance can be degraded by enzymes in vitro and never be degraded in vivo or in the environment because of a lack of proper enzyme(s) in situ (or simply a lack of water). This is the reason why biodegradation is referred to as limited to degradation resulting from cell activity. (See enzymatic degradation.) The definition in [2] is also confusing because a compounded polymer or a copolymer can include bioresistant additives or moieties, respectively. Theoretical biodegradation should be used to reflect the sole organic parts that are biodegradable. (See theoretical degree of biodegradation and maximum degree of biodegradation.) Note 2: In vivo, degradation resulting solely from hydrolysis by the water present in tissues and organs is not biodegradation; it must be referred to as hydrolysis or hydrolytic degradation. Note 3: Ultimate biodegradation is often used to indicate complete transformation of organic compounds to either fully oxidized or reduced simple molecules (such as carbon dioxide/methane, nitrate/ammonium, and water. It should be noted that, in case of partial biodegradation, residual products can be more harmful than the initial substance. Note 4: When biodegradation is combined with another degrading phenomenon, a term combining prefixes can be used, such as oxo-biodegradation, provided that both contributions are demonstrated. Note 5: Biodegradation should only be used when the mechanism is proved, otherwise degradation is pertinent. Note 6: Enzymatic degradation processed abiotically in vitro is not biodegradation. Note 7: Cell-mediated chemical modification without main chain scission is not biodegradation. (See bioalteration.) (8).

These distinctions are important because not all bio-based polymers can be reliably used when searching for environmentally friendly plastics. As stated in note 4 of the bioplastic definition, above, most of the bioplastics that are produced today are not superior to the crude oil plastics because they are also not environmentally biodegradable. Partial biodegradable polymers can become recalcitrant and toxic, and can even be considered less environmentally friendly than fully non-biodegradable petro-based plastics. This makes PHA a standout bioplastic, as it perfectly fits the description of a fully biodegradable bio-based polymer since it can be naturally biodegraded into water and carbon dioxide completely.

Figure 10. Cycle of biodegradation (21).

In order to begin the process of creating this biopolymer for use in plastic manufacturing two questions must be asked first: 1) What microorganism is the best to use for production of PHA based on yield and cost? 2) What hydrocarbon source should be used to optimize production? The answer to these questions lies in the studies that have been performed by multiple research teams within recent years.

Isolation and Identification of PHA producing microorganisms (AS)

In order to determine a possible PHA-producing microorganism, certain microbiological techniques must be executed to identify and isolate a bacterium strain that produces the bio - polymer. PHA must be produced in quantities that are large enough to be economically significant for extraction purposes. The methods provided by researchers begin with the collection of bacterial communities that might contain hydrocarbon-degrading bacteria. Sources that would contain such bacteria are matter that is high in hydrocarbons, such as municipal waste waters and other waste facilities (20). After collection, a series of dilutions should be made to control the amount of bacteria that will be looked at for identification. The bacterial solution can be plated on carbon-rich nutrient agar to allow for enhanced growth of the wanted hydrocarbon- degrading bacteria. The next step is to add a series of dyes that allow for differentiation of PHA- producing bacteria and PHA non-producing bacteria; they ultimately will be dyed different colors and will fluoresce differently under UV light. The dyes being used for this process can differ depending on the researcher, but all dyes used are for the detection of PHA. Isolation of the supposed PHA-producing bacteria allows for closer inspection of the different species and strains of the bacteria. Morphological characteristics must be observed, and biochemical tests must be performed in order to truly identify which bacteria are producing large amounts of PHA for future use. In the graph below, researchers have found that Enterococcus sp. (NAP11) and Brevundimonas sp. (NAC1) produced the largest amount of PHA, compared to the standard of Ralstonia eutropha and other bacterial test species (20).

Figure 11. PHB production of different bacteria (20).

While these two bacterial groups have been found to be large producers of PHA, they by no means need to be the only type of bacteria to be used for its synthesis. There are a multitude of other microorganisms that could be considered for the use of mass production, and there are probably still many undiscovered species and strains that produce PHA as well, perhaps in even greater amounts than their well-studied counterparts. However, there have been certain patents that have been filed for different PHA producing bacteria, so depending on the types of patents documented, the type of bacteria to be used for this could be restricted (22).

Production of PHA (AS)

The nutrient source which will be used to enhance growth of the bacteria and also allow for a greater production of PHA must be taken into consideration. The material to be used should be both cheap and high in hydrocarbons. This makes organic waste products a good choice as a substrate. An added benefit to the use of waste products is that it gives them a useful purpose instead of being funneled directly back into the environment and their properties lost to us. Different research groups and companies have proposed the use of different types of wastes such as human/animal fecal waste waters, paper and cardboard waste material, malt wastes, and even certain hydrocarbon based pollutants. These are just a few examples, and potentially any organic waste could be used. In fact, the greater variety of wastes that can be utilized in this endeavor could be more beneficial than the use of a single source, because there is the potential to convert all organic wastes into usable products through this method of PHA production.

Waste material as a food source for these bacteria allows for a large bulk of hydrocarbons to be used such as starch, glycogen, glycerol, amylopectin, sucrose, glucose, and lipids. Each of these can be broken down into simple components, and built back up into PHA monomers and polymers due to biochemical metabolic reactions that occur within cells. The central component of these catabolic and anabolic processes is Acetyl coenzyme A, or simply Acetyl-CoA, a major factor in many biochemical reactions especially the tricarboxylic acid (TCA) cycle. Depending on the organism and the carbon source being utilized, the exact metabolic pathway that creates PHA can differ because certain bacteria may have diverse enzymes that can be used in these processes. However, research has shown that PHA production can be summarized by eight pathways within hydrocarbon-degrading bacteria that are used (22). The pathways are shown below.

Figure 12. PHA biosynthesis pathways (22). When sugars like starch glycogen and glucose are used as the hydrocarbon source, Acetyl CoA is produced through glycolysis and the pyruvate dehydrogenase complex (not shown in above image). Fatty acid usage, however, utilizes the β-Oxidation pathway of fatty acid catabolism. The PHA that is produced can be stored within the cell which will be broken down later into usable carbon sources for energy.

Extraction of PHA (AS)

After PHA is produced by a researcher’s organism of choice, the next important step in the utilization of PHA is its extraction from within the cell. There are several extraction methods that can be chosen from. One such example is by genetically modifying the bacteria to excrete PHA under certain environmental conditions. However, most other options to extract PHA involves chemical or enzymatic lysis and degradation of the cell and its components. The initial methods of extracting PHA was to use alkaline hypochlorite to dissolve the cellular material around the lipid bodies that are storing PHA (23), (24). Other methods of extraction that have been utilized by different researchers include the use of methylene chloride, propylene carbonate, dichloroethane, and chloroform. Hypochlorite can be used in conjunction with chloroform in the hypochlorite-chloroform dispersion method of extraction. The hypochlorite allows for the initial dissolving of cellular components, and the chloroform allows for the precipitation of the PHA out of the solution to be collected (25). This type of extraction method is the most practical due to its quickness and ease. Other methods of extraction through lysing and precipitation have been utilized through similar processes by different research teams. However, the choice of which Lysing-Precipitation techniques to use is based primarily on preference due to their similar PHA yields.

Cost of PHA (AS)

Currently, the production of PHA is still in the developmental stages and has some logistics that are being worked out by bioplastic manufacturers such as the aforementioned use of waste materials and the overall facilitation of mass production. Waste use, while being a great source of hydrocarbons, is being underutilized in the field, because bioplastics are not being properly recognized by the major plastic manufacturers due to the manufacturers’ large pre-existing income and revenue. This lowers the amount of money put into research of PHA production causing a slow and staggered advancement in this field. Today, the process of making PHA is 20% to 80% more expensive than the process of making petrochemical plastics. However, this excludes the methods and machinery costs involved in the extraction of petroleum essential in petrochemical plastic production. The manufacturers analyze these misleading statistics and assume that they are saving money, when in reality they are spending billions on crude oil extraction alone. If they were to support the research of PHA, then within a few short years, the cost of PHA production would significantly decrease well below the amount they are already spending in petrochemical plastic production (26).

Conclusion (AS)

PHA as an overall product is great in both terms of economic and environmental enhancement. Its use in prosthetic devices will improve the industry due to the similar functionality to petrochemical plastics, but its cost effective manufacturing process, and its safe disposal methods make it far superior than its petroleum-based counterparts. The plastic and prosthetic manufacturers will benefit from the low cost, the consumer will benefit from the functionality of the prosthetic, and the environment will benefit from the biodegradable properties of the product. Currently, PHA is not being used to its full potential. While some corporations have already started using it in their products, it should be done on a global scale. It will eliminate harmful environmental practices and help further advance medical technology for the future.

Community Action: A Proposal to Initiate PHA Use in Plastics and Prosthetics (FK)

There are a multitude of prosthetic manufacturing companies throughout the country, one of which, we visited to learn more about the prosthetic industry. After some research we traveled to Hanger, Inc., a prosthetics and orthotics company in Edison, New Jersey. We were given a full tour and explanation of the process of making prosthetics, designing the mold, which materials are used, and the amount of time it takes to make the molds and prosthetics. It was clear that making prosthetics was not a simple or quick process, and cost-efficiency as well as precision were crucial to be successful in the prosthetics industry. Adam Katz, a prosthetist in the Edison branch, told us how the plastics he purchased from companies varied depending on who was selling them at a lower cost at the time. Lastly, he informed us that prosthetic disposal was simply throwing them away like any other garbage in the bin. This discovery combined with what we learned through the tour confirmed that it was possible to use PHA-based plastic as an alternative to the standard petro-based plastic in prosthetics, for it would benefit not only the industry but the environment as well. As previously noted, PHA plastic will be a cheaper alternative if implemented, and it is fully biodegradable, so when prosthetic companies discard material, instead of sitting in a landfill, it can be broken down into harmless substances and return to the environment.

Our solution was to send proposals to the companies most involved in this field: plastic distributors, plastic manufacturers, and prosthetic companies. Sending a total of three proposals, we explained the benefits of incorporating PHA in their plastic production and usage. We also are providing exposure to the PHA problem through these proposals, spreading awareness to the public. The letters are shown below.

To Emco Displays,

As a plastics distributor, I am certain you are already aware of the crucial function plastics have in the modern world today. Plastic has benefited technology, daily usage, as well as the scientific and medical community. With such high demand, large quantities of plastic are distributed by your company to those in need of it. One must wonder, then, what impact there is in procuring the plastic in the first place, and how this creates a domino effect of harming the environment. Most plastics are derived from petrochemicals, which are not only expensive but extremely hazardous to the environment. However, bioplastics, specifically polyhydroxyalkanoate (PHA), is equally efficient as the petrochemical-based plastics and are also biodegradable, therefore a much better alternative. When plastics are made, they first start as petroleum which is extracted from the earth. It is then distilled and refined until the desired plastic is created, some of which include polyethylene, polypropylene, and nylon. This process endangers the ecosystems from where the extraction occurs, as well as the ecosystems where these non-biodegradable plastics are disposed.

PHA is naturally-produced polymers made by microorganisms, most of which are hydrocarbon- degrading bacteria. This means that the PHA they make are biodegradable, and waste products can be used by the bacteria to make biopolymers. Once PHA is produced, they’re extracted and manufactured into plastics. This method utilizes a biological process that eliminates the harmful ramifications of fracking and is also environmentally friendly; the plastics made from PHA would be biodegradable, therefore any plastic that gets discarded would naturally degrade, unlike the petrochemical-based plastic.

Using PHA to make plastics would be a cost-effective, biological process that spares the earth and its ecosystem a vicious cycle of exploitation and environmental destruction. Distributing this type of plastic would not only be beneficial to your company, but would be a catalyst to a much bigger picture: a future where crude oil is no longer necessary to make plastic, and thus sparing the earth and our ecosystem the harmful ramifications of oil extraction.

To Hanger Inc:

As a prosthetics company, I am certain you are already aware of the crucial function prosthetics and plastics have in the modern world today. Plastic has benefited technology, daily usage, as well as the scientific and medical community. With such high demand of prosthetic devices, plastic is distributed to your company to be fitted for those in need of it. One must wonder, then, what impact there is in procuring the plastic in the first place, and how this creates a domino effect of harming the environment. Most plastics are derived from petrochemicals, which are not only expensive but extremely hazardous to the environment. However, bioplastics, specifically polyhydroxyalkanoate (PHA), is equally efficient as the petrochemical-based plastics and are also biodegradable, therefore a much better alternative for plastics in prosthetics.

When plastics are made, they first start as petroleum which is extracted from the earth. It is then distilled and refined until the desired plastic is created, some of which include polyethylene, polypropylene, and nylon. These plastics are utilized in the creation of prosthetics and whatever remains is discarded. This process endangers the ecosystems from where the extraction occurs, as well as the ecosystems where these non-biodegradable prosthetics are discarded.

PHA is naturally-produced polymers made by microorganisms, most of which are hydrocarbon- degrading bacteria. This means that the PHA they make are biodegradable, and waste products can be used by the bacteria to make biopolymers. Once these PHA is produced, they’re extracted and manufactured into plastics, which are then used to make prosthetics. This method utilizes a biological process that eliminates the harmful ramifications of fracking and is also environmentally friendly; the prosthetics made from PHA would be biodegradable, therefore any prosthetic that gets discarded would naturally degrade, unlike the petrochemical-based prosthetic.

Using PHA to make prosthetic plastics would be a cost-effective, biological process that spares the earth and its ecosystem a vicious cycle of exploitation and environmental destruction. Using this type of plastic in your prosthetics would not only be beneficial to your company, but would be a catalyst to a much bigger picture: a future where crude oil is no longer necessary to make plastic, and thus sparing the earth and our ecosystem the harmful ramifications of oil extraction.

To Evco Plastics,

As a plastics manufacturer, I am certain you are already aware of the crucial function plastics have in the modern world today. Plastic has benefited technology, daily usage, as well as the scientific and medical community. With such high demand, plastic is distributed by your company to those in need of it. One must wonder, then, what impact there is in procuring the plastic in the first place, and how this creates a domino effect of harming the environment. Most plastics are derived from petrochemicals, which are not only expensive but extremely hazardous to the environment. However, bioplastics, specifically polyhydroxyalkanoate (PHA), is equally efficient as the petrochemical-based plastics and are also biodegradable, therefore a much better alternative.

When plastics are made, they first start as petroleum which is extracted from the earth. It is then distilled and refined until the desired plastic is created, some of which include polyethylene, polypropylene, and nylon—products that are listed in your distribution. This process endangers the ecosystems from where the extraction occurs, as well as the ecosystems where these non- biodegradable plastics are disposed.

PHA is naturally-produced polymers made by microorganisms, most of which are hydrocarbon- degrading bacteria. This means that the PHA they make are biodegradable, and waste products can be used by the bacteria to make biopolymers. Once these PHA is produced, they’re extracted and manufactured into plastics. This method utilizes a biological process that eliminates the harmful ramifications of fracking and is also environmentally friendly; the plastics made from PHA would be biodegradable, therefore any plastic that gets discarded would naturally degrade, unlike the petrochemical-based plastic.

Using PHA to make plastics would be a cost-effective, biological process that spares the earth and its ecosystem a vicious cycle of exploitation and environmental destruction. Manufacturing this type of plastic would not only be beneficial to your company, but would be a catalyst to a much bigger picture: a future where crude oil is no longer necessary to make plastic, and thus sparing the earth and our ecosystem the harmful ramifications of oil extraction.

References

1. Smith, Douglass G. (2005). Senior Health Prosthetic Rehabilitation and Technology Options and Advances for Seniors. A Publication of Amputee Coalition of America In Motion. Volume 15. Retrieved from website: http://www.amputee- coalition.org/inmotion/nov_dec_05/pros_rehab_tech_seniors.html 2. Lorenzi Rosella. (2012). Ancient Egyptian Fake Toes Earliest Prosthetics. Discovery News. Retrieved from website: http://news.discovery.com/history/ancient-egypt/ancient- egypt-wooden-toes-prosthetics-121002.htm 3. Norton Kim, M. (2007). A Brief History of Prosthetics. In Motion. Volume 17. Retrieved from website: http://www.amputee- coalition.org/inmotion/nov_dec_07/history_prosthetics.html 4. Copeland, Bill. (2001). The Process of Making a Prosthesis. Retrieved from website: http://www.amputee-coalition.org/first_step/firststepv2_s2a04.html 5. Made How, (2015). How Products Are Made. Volume 1. Retrieved from website: http://www.madehow.com/Volume-1/Artificial-Limb.html 6. Kopeliovich, Dmitri. (2014). Injection Molding of Polymers. Substances and Technologies. Retrieved from website: http://www.substech.com/dokuwiki/doku.php?id=injection_molding_of_polymers&s=inj ection%20molding 7. The Metal Casting. Extrusion Process. Retrieved from website: http://www.themetalcasting.com/extrusion-process.html 8. Vert, Michel, et al. (2012). Terminology for biorelated polymers and applications (IUPAC Recommendations 2012). Pure Appl. Chem. Volume 84. Retrieved from website: http://pac.iupac.org/publications/pac/pdf/2012/pdf/8402x0377.pdf 9. The Plastics Industry Trade Association, (2015). History of Plastics. Retrieved from website: http://www.plasticsindustry.org/AboutPlastics/content.cfm?ItemNumber=670 10. Flintoff, Corey. (2012) Where Does America Get Oil? You May Be Surprised. Npr. Retrieved from website: http://www.npr.org/2012/04/11/150444802/where-does-america- get-oil-you-may-be-surprised 11. Independent Statistics & Analysis U.S. Energy Information Administration, (2015). Drilling Productivity Report. Retrieved from website: http://www.eia.gov/petroleum/drilling/#tabs-summary-2 12. Natural Gas: From Wellhead to Burner Tip. (2013). Retrieved from website: http://naturalgas.org/naturalgas/exploration/ 13. Reed, Lisa. (2015). [Online Image]. Retrieved from website: http://www.dummies.com/how-to/content/what-is-the-environmental-impact-of- petroleum-and-.html 14. American Chemistry Council, (2015). How Plastics Are Made. Retrieved from website: http://plastics.americanchemistry.com/Education-Resources/Plastics-101/How-Plastics- Are-Made.html 15. Independent Statistics & Analysis U.S. Energy Information Administration, (2014). How Much Does It Cost to Produce Crude Oil and Natural Gas?. Retrieved from website: http://www.eia.gov/tools/faqs/faq.cfm?id=367&t=6 16. Independent Statistics & Analysis U.S. Energy Information (2014). How Much Oil Is Used to Make Plastic? Retrieved from website: http://www.eia.gov/tools/faqs/faq.cfm?id=34&t=6 17. Kaiser, Mark J., and Snyder, Brian F. (2012). Reviewing rig construction factors. Offshore. Retrieved from website: http://www.offshore-mag.com/articles/print/volume- 72/issue-7/rig-report/reviewing-rig-construction-cost-factors.html 18. Brown, Josh. (2011). Meet the Nurdles: Norfolk’s New Industry. The Virginian-Pilot. Retrieved from website: http://hamptonroads.com/2011/04/meet-nurdles-norfolks-new- industry 19. O’Hanlon, Larry. (2010). How Crude Oil Can Harm You. Discovery News. Retrieved from website: http://news.discovery.com/human/health/crude-oil-harms-humans.htm 20. Bhuwal, Anish Kumari, et al. (2013). Isolation and Screening of Polyhydroxyalkanoates Producing Bacteria from Pulp, Paper, and Cardboard Industry Wastes, International Journal of Biomaterials, Volume 2013. Retrieved from website: http://www.hindawi.com/journals/ijbm/2013/752821/cta/ 21. Moralejo Garate, H. (2014). Biopolymer Production by Bacterial Enrichment Cultures Using Non-Fermented Substrates. Institutional Repository. Retrieved from website: http://repository.tudelft.nl/view/ir/uuid:4ed9e1e3-c038-47c4-b15e-5c16edd339b8/ 22. Chen, Guo-Qiang. (2010). Plastics Completely Synthesized by Bacteria: Polyhydroxyalkanoates. Plastics from Bacteria Natural Functions and Applications. Microbiology Monographs, Volume 14. Springer-Verlag Berlin Heidelberg. Retrieved from website: http://yunus.hacettepe.edu.tr/~damlacetin/kmu407/index_dosyalar/11.%20makale.pdf 23. Williamson, D. H., and Wilkinson, J. F. (1958). Journal of General Microbiology. Vol 19, pg 198-209. Retrieved from website: http://mic.sgmjournals.org/content/19/1/198.full.pdf 24. Lundgren, D. G., et al. (1965). Characterization of Poly-β-Hydroxybutyrate Extracted from Different Bacteria. Journal of Bacteriology. Vol 89, pages 245-251. Retrieved from website: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC315576/pdf/jbacter00430- 0275.pdf 25. Hahn, Sei Kwang, et al. (1993)."The Recovery of Poly(3-Hydroxybutyrate) by Using Dispersions of Sodium Hypochlorite Solution and Chloroform." Biotechnology Techniques. Vol. 7, pg. 209-212. 26. Markets and Markets, (2013). Polyhydroxyalkanoate (PHA) Market, By Application (Packaging, Food Services, Bio-medical, Agriculture) & Raw Material — Global Trends & Forecasts to 2018. Retrieved from website: http://www.marketsandmarkets.com/Market-Reports/pha-market-395.html Letters to the Editors

To the Editor of the Daily Targum:

Plastics incorporated in prosthetics are derived from petrochemicals whose extraction, manufacturing, and disposal contributes to the world’s pollution and the high cost of the prosthetic. Petroleum based plastics is produced by first extracting the petroleum from the ground using drills, refining it into monomers, and then linking the monomers using polymerization reactions. These plastics can be replaced by a bio-based, biodegradable plastic such as polyhydroxyalkanoates (PHA). PHA is a category of polyesters produced by bacteria using high carbon sources such as waste materials, and if used in prosthetics, they will make it more environmentally friendly due to its biodegradability and the process by which it is made. Additionally, this process would be less expensive than that of drilling and extracting petrochemicals which could potentially reduce the cost of prosthetics in the future.

Sincerely, Karissa Tuason

To the Editor of New England Journal of Medicine,

Most prosthetic manufacturing companies use plastics that are derived from petrochemicals, which are not only expensive but extremely hazardous to the environment. However bioplastics, specifically polyhydroxyalkanoate (PHA), is equally efficient as the petrochemical-based plastics and are also biodegradable, therefore a much better alternative. When plastics are made, they first start as petroleum which is extracted from the earth. It is then distilled and refined until the desired plastic is created, some of which include polyethylene, polypropylene, and nylon. These plastics are utilized in the creation of prosthetics and whatever remains is discarded. This process endangers the ecosystems from where the extraction occurs, as well as the ecosystems where these nonbiodegradable prosthetics are discarded.

PHA is naturally-produced polymers made by microorganisms, most of which are hydrocarbon- degrading bacteria. This means that the PHA they make are biodegradable, and waste products can be used by the bacteria to make biopolymers. Once these PHA is produced, they’re extracted and manufactured into plastics, which are then used to make prosthetics. This method utilizes a biological process that eliminates the harmful ramifications of fracking and is also environmentally friendly; the prosthetics made from PHA would be biodegradable, therefore any prosthetic that gets discarded would naturally degrade, unlike the petrochemical-based prosthetic.

Using PHA to make prosthetic plastics would be a cost-effective, biological process that spares the earth and its ecosystem a vicious cycle of exploitation and environmental destruction.

Sincerely, Farrah Khan To the Editor of Advanced Functional Materials,

The modern prosthetic industry produces plastics that are composed of harmful chemicals which come from crude oils and natural gases that must be extracted from deep within the earth. The process of obtaining these raw materials is both costly and can be extremely detrimental to the environment. The amount of money used for removing these petroleum based oils from the ground makes up a majority of the expenses needed in the entire plastic manufacturing process. Furthermore, the process of extraction has been a substantial hazard to surrounding ecosystems.

To avoid these two harmful aspects of producing petro-based plastic, the cost-effective and environmentally friendly alternative would be plastics composed of bio-based polymers. More specifically polyhydroxyalkanoate (PHA), a thermoplastic derived directly from biological processes that occur within living bacterial cells, is a better alternative due to its biodegradability and attainability. Additionally, PHA is able to be crafted into different types of plastic with a variety of properties, which can be useful especially in the medical field where multiple materials are utilized in equipment such as prosthetics and orthotics.

Incorporating these alternative bio-polymers into this field will substantially improve the environmental effects caused by plastic corporations, as well as decrease the costs associated with prosthetic manufacturing.

Sincerely, Anthony Sena