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Home , Peptization, Phase (matter), Solvent, Tyndall effect

COLLOIDAL

Department of Medical Pomeranian Medical University

1 COMPONENTS OF THE SYSTEM -chemicals which create the system. They create different type of - which makes the system to exists in various phases.

PHASE – part of the system is separated from other phases with distinct border where sudden change in physico-chemical changes takes place. • containing one component – pure substance • Phase containing more than one component -

SOLUTION – of two or more components dissolved in (solvent-subtance in quantitative excess over other componet)

2 SYSTEMS Systems can be divided due to: 1) number of components: ➢ one-component ➢ multicomponent 2) number of phases : ➢ single phase ➢ multiple phase

SYSTEMS:

HETEROGENOUS –multiplephase (seemingly single-phase), heterogeneous; eg. with (heterogeneous, two-phase, single- component system ), water with (heterogeneous, two-phase, two- component system ) HOMOGENOUS –single-phase, homogeneous throughout the , both chemically and physically; e.g. glucose solution (homogeneous single phase, two components system)

3 Types of solutions depending on size of dispersed phase in dispersive medium

TYPE OF SOLUTION DIAMETER OF OF DISPERSED PHASE True solution < 10-9 m (<1nm) (homogeneous) Colloidal (heterogeneous) 10-9 - 10-7 m (1-100 nm)

Suspension > 10-7 m (>100 nm)

4 COLLOIDAL SOLUTIONS

COLLOIDAL SOLUTIONS – heterogenous dispersive system with distinguished continuous phase (solvent) and discontinuous dispersed phase with diameter of 10-9 - 10-7 m (1 – 100 nm, up to 500nm)

All living cells are sets of various colloidal systems.

Colloidal systems are widespread :

in animate nature (proteins, carbohydrates)

in inanimate nature (clay, fog, volcanic )

synthetic materials (soap, colorants, colloidal sulphur, metal ) 5 COLLOIDAL SOLUTIONS

COLLOIDAL SOLUTION – HETEROGENEOUS system - with of 10-9-10-7m in diameter (1 – 100 nm, up to 500 nm)

10-9 m = 1 nm = 0.001 micron 10-7 m = 100 nm = 0.1 micron -6 10 m = 1000 nm = 1 micron 6 Properties of (1): 1. They can be seen in ultra–microscope. Attention: the difference between an ultra-microscope and ordinary one is that in the former the light falls laterally on the under study, instead of “from below”. The ordinary microscope with x400 magnifications has limitations for particles below 1 micron, but it is still able to show “general structures of system”. 2. They are not dialyzed –> Colloidal particles will not be separated by membranes (like bladder or parchment paper), because they will not diffuse through a membrane. 3. They show permanent Brownian motions – mostly particles smaller than 100nm are able to do strong Brownian motion. 4. They show Tyndall effect – visible light scattering by the colloidal particles. 5. They may coagulate –> colloid particles become agglomerated.

7 Tyndall Effect

This is light scattering by colloidal solution (for example by dust, fog, milk,etc.). When light beam passes through the colloidal it is scattered and therefore is visible. When light beam passes through the solution, like water, it is not scatter and therefore it cannot be seen. Intensity of this phenomena is larger when difference between light scattering of dispersive medium is larger then light scattering of dispersed phase.

8 Solutions vs Colloids

The Tyndall Effect

True Solution e.g. water Colloidal mixture, e.g. milk

9 The Tyndall Effect

10 CLASSIFICATION OF COLLOIDAL SYSTEMS DEPENDING ON :

I. STATE OF DISPERSING AND DISPERSED PHASE

Disperssed Disperssing phase COLLOID EXAMPLE phase

Gas - - Liquid Gas liquid Fog, clouds, Gas Aerosol solid Smoke, dust Gas Liquid Foam Foam: soap, beer Liquid Liquid Creams, , milk, mayonese, butter Solid Liquid Zol solutions

Gas Solid Foam Pumice, styrofoam Liquid Solid Emulsion solid , opal Solid Solid Zol solid rubin, colour cristals

11 CLASSIFICATION OF COLLOIDAL SYSTEM :

II. Size of colloidal particles: ➢ monodispersive (particles of dispersed phase have the same dimensions) ➢ polydispersive (particles of dispersed phase have different dimensions)

III. Affinity of dispersed phase to dispersing medium :

•liophilic colloids – they have large affinity to solvent particles; colloidal particles are surrounded by solvent particles

• liophobic colloids – they have small affinity to solvent and adsorb on the surface of particles large quantities of one type of

12 CLASSIFICATION OF COLLOIDAL SYSTEM DEPENDS ON (cont.)

IV. Quality of dispersed phase:

Emulsions – the dispersed phase is of nonpolar character (e.g. lipids) and does not have affinity to dispersion medium (e.g. water). have hydrophobic character and are also called suspensions or irreversible colloids. • In living organisms example of emulssions are lipids. Small particles of lipids can be dispersed in water thanks to the compounds called emulsifiers. Emulsifier – this is compund which can be „dissolved” in both – dispersed phase and dispersion medium. For example, consumed are emulsified by bile acids contained in bile.

They have ability to decrease , like soap in water. 13 AgI structure precipitated with excess of KI

nucleus LAYER Nucleus of colloidal +adsorbtion layer

core DIFFUSION micelle 14 COLLOIDS STRUCTURE

Hydrophobic micell are mostly built by oxides, sulphates, hydroxides of heavy metals

Hydrophilic colloids are built usually by large such as : proteins. Their stability is due to the presence of water molecules adsorbed on their surface.

15 Coagulation (1)

COAGULATION – it is an ability of colloid particles to combine with each other and form larger structures called agregates. After reaching appropriate size they loose ability „to flow” and they sediment on the bottom.

Coagulation can be caused by: 1. radioactivity– beta ray 2. heating – coagulation of protein (egg) 3. or of dispersive medium 4. dehydration, for example by using , 5. addition of electrolite to colloid

16 Coagulation (2)

Peptization – process opposite to coagulation – breaking coagulate and return from coagulate to colloid.

SOL coagulation

peptization

17 Coagulation (3)

Hydrophilic colloid (reversible) – takes place when water coat has been removed

Hydrophobic colloids (irreversible) – takes palce when electrical charge present on the surface becomes neutralized.

18 COLLOIDS HYDROPHOBIC HYDROPHILIC

Strongly hydrated Salts with multivalance cations

coagulate Water particles

19 Coagulation (4)

Conditions for salting out of protein

• Proteins are easiest to be salted out in their isoelectric point (pI) because they do not posses any electrical charge, they attract themselves strongly and create aggregates, which to precipitation (lack of electrical charge helps molecules to aggregate, which allows them to precipitate from solution).

• In pH different from pI, protein due to presence of the surface charge can exist in solution despite not having water coat ( they behave similar as hydrophobic colloids)

• Addition of small amount of neutralizing electrical charge ions leads to protein precipitation. Such protein does not posses either electrical charge or water coat.

20 Conditions for salting out protein from solution

Protein Protein cation Protein in pI

Base addition Acid addition

pH increase pH decrease dyhadration Charge lost due to charge lost due cation addition to anion addition

precipitate Protein cation Protein anion suspenoid 21 Salting out of proteins

• Proteins are easy to -out in isoelectric point (pI) and in this state they easily sediment as larger aggregates.

[Isoelctric point it is pH at which proteins have no electrical charge].

• In pH different than pI protein can exist in solution despite having no hydrophilic coat.

http://elte.prompt.hu/sites/default/files/tananyagok/IntroductionToPracticalBiochemistry/ch05s04. 22 html PROTECTIVE ROLE OF HYDRPHILIC COLLOIDS ON HYDROPHOBIC COLLOIDS Hydrophilic colloids show higher stability than hydrophobic colloids, because of two stabilizing factors: • hydration layer • sometimes - particles have the same charge (which can be result of dissotiation of acidic or basic groups being present in colloidal particle)

Hydrophilic colloids are acting protective on hydrophobic colloids – addition of hydrophilic colloid to hydrophobic is causing creation of stable system from which it is difficult to precipitae suspended particles (e.g. small amount of protein added to colloidal protects it from coagulation).

Protective role of colloid can be determined quantitatively by providing gold number ( gold number it is the smallest amount of miligrams of protective colloid in respect to pure substance which is able to protect 10cm3 0,1% of formaldehyde gold zol, against change from red to purple after addition of 1cm3 10% NaCl ) 23 Colloids in fluid therapy (1)

Fluid therapy (1):

treatment consisting of fluid intake (usually intravenous, intraarterial or subcutaneous)

often used in hospital as well as emergency

24 Colloids in fluid therapy (2)

Fluid therapy (2):

compensating fluid deficiency is one of the most urgent tasks in the treatment of critically ill patients with hypovolemia ✓ hypovolemia

- a decrease in intravascular volume, resulting in insufficient functioning of the normal mechanisms to hold fluid in the vascular bed - may exists as a reduced, normal or increased extracellular volume

- large hypovolemia leads to hypovolemic shock

Keeping adequate fluid therapy contributes to the reduction of organ disfunction and shortens hospitalization time.

25 Colloids in fluid therapy (3)

Basic conditions requiring fluid therapy :

all forms of shock (usually hypovolemic shock, but also anaphylactic shock, septic, neurogenic)

dehydration due to increased fluid loss (diarrhea, )

burns (increase in vascular permeability in case of burns results in the loss of fluid)

other fluid deficiency states

26 Colloids in fluid therapy (4)

The objectives of conducting fluid therapy :

replenishment of and nutrients

replenishing fluids (ex. blood lost as a result of hemorrhage)

supply of in combination with liquid (when the should be administered for several minutes or at high )

27 Colloids in fluid therapy (5) Fluids used for fluid therapy :

Crystalloids (aqueous solutions of electrolytes or glucose, such as 0.9% NaCl, 5% glucose solution, Ringer's solution, polyelectrolitic isotonic fluid "PWE") - used for blood loss up to 15% of body weight

- indicated in case of patients who have deficiency of fluid in the interstitial space or patients with deficiency of electrolytes (burned and dehydrated)

Colloidal solutions (natural and synthetic )

- used for blood loss exceeding 15% of body weight

- indicated in situations when supply of crystalloid is insufficient or there are contraindications for their use (eg. risk of pulmonary edema)

- it is estimated that administration of 1 liter of colloidal solution corresponds to the administration of 4 liters of crystalloid 28 Colloids in fluid therapy (5) cont.

Blood and blood-related products : - packed red cells, (RBC, pRBC, PRBC),

- fresh frozen (FFP),

- blood plates concentrate

http://reference.medscape.com/drug/ffp-octaplas-fresh-frozen-plasma-999499

29 Colloids in fluid therapy (6)

Colloidal solutions

natural synthetic

gelatines - made of collagen obtained Hydroxyethyl starch (HAES/HES) from tendons, skin and bones -Synthesized from amylopectine - Small molecular weight - 35 kDa -- HES: Plasmasteril (6% HES 450/0.7) and 3%, 6%, 10% solutions HES:, (fast urinary excretion ) HES 200/0.5, HES 200/0.5, HES 130/0.4 - preferred: - short-term volume effect ✓show beneficial rheological effect and inhibition of - minimal effect on hemostasis blood platelets aggregation Human albumin ✓ does not accumulate in plasma and tissues and does - has an effect for 24–36 h, not affect hemostasis and renal function - reraly causes allergic reaction - big quantities may cause coagulopathy - used in: - consisting of 200-450 glucose molecules ✓ severe protein deficiency states , - have been used in the clinic :

✓extensive burns, ✓ 6% i 10% dextran solution 40 (T1/2= 2-3 h)

✓ brain edema ✓ 6% dextran solution 70 (T1/2= 6-8h) - used for supplementing intracellular volume, improving ✓ ascites reological properties of blood, and in therapy •expensive - among colloids – the most often cause of anaphylactic reactions 30 Colloids in fluid therapy (7)

Colloidal solutions - advantages :

allow for faster replenishment of intravascular fluid (hemorrhage, shock)

compared to crystalloids provide faster, stronger and longer-lasting volume effect - increase oncotic , which leads to the movement of water into the vessel

- remain for a long time in the intravascular compartment (2-12 hours) - after administration of colloids an increase in intravascular volume is observed – from 100 % to up to 400%

have a positive impact on hemodynamics, organ perfusion and supply

31 Colloids in fluid therapy (8)

Colloidal solutions -disadvantages :

can cause allergic reactions

after the administration of large amounts, they may cause:

- dilution effect of blood components: proteins, coagulation factors

- decrease in hematocrit level

price

32 Colloids in fluid therapy (9)

Ideal colloidal solution:

should not accumulate in the plasma and tissues, but readily undergo elimination from the body HES 130/0,4

should not affect hemostasis and renal function

should be suspended in crystaloid solution to avoid dehydration of extracellular space and impairment of functions

33 The End

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