Proceedings of Spie

PROCEEDINGS OF SPIE SPIEDigitalLibrary.org/conference-proceedings-of-spie Effect of biodegradation on spectroscopic properties of Sm3+ doped 45S5 bioglass Agata Baranowska, Jan Ryszard Dąbrowski, Marcin Kochanowicz, Jan Dorosz Agata Baranowska, Jan Ryszard Dąbrowski, Marcin Kochanowicz, Jan Dorosz, "Effect of biodegradation on spectroscopic properties of Sm3+ doped 45S5 bioglass," Proc. SPIE 10808, Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2018, 1080833 (1 October 2018); doi: 10.1117/12.2500274 Event: Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2018, 2018, Wilga, Poland Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 10/3/2018 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use Effect of biodegradation on spectroscopic properties of Sm3+ doped 45S5 bioglass Agata Baranowska1*, Jan Ryszard Dąbrowski 1, Marcin Kochanowicz2, Jan Dorosz2 1Bialystok University of Technology, Faculty of Mechanical Engineering, 45C Wiejska St. 15-351 Bialystok, Poland 2Bialystok University of Technology, Faculty of Electrical Engineering, 45D Wiejska St. 15-351 Bialystok, Poland *[email protected] ABSTRACT In the article, we showed the unconventional method to determine the degradation of Bioglass 45S5 doped with samarium ions used as an optical probe. The strongest emission at the wavelength of 601 nm has been observed under 405 nm laser excitation. We used the alternative method of fiber drawing from the 45S5 glass. Bioactive glass fiber was immersed in Sorensen buffer at temperature 37°C. In situ analysis of luminescence signal of glass fiber shown a decrease in intensity within 24 hours. This effect was connected with partial surface degradation of bioglass fiber. Keywords: biodegradation, bioglass, samarium ions, luminescence 1. INTRODUCTION The bioactivity of glass is still a very interesting area of materials engineering. In 1969, Larry Hench developed the first bioactive glass Bioglass 45S5 [1], which is the most popular and useful material in clinical applications today. The reason is its ability to degrade in physiological solutions [2] and to create a surface layer of hydroxycarbonate apatite (HCA). The second feature could be used in self-repair of bone cracks due to the ability of biodegradation and formation of new bone [3]. In practice, the glass fibers are required to produce biocompatible nanocomposites, which are applied in vitro experiments [4]. In fact, the conventional techniques to analyze the degradation of nanocomposites like: mass- reduction [5], analysis of ions contamination [6], pH changes [7] and measurements of HCA layer thickness [8] are quite complex due to multistep processing. Thus, optical properties of bioglass like transmission and luminescence can be used to obtain valuable information about gradual degradation of 45S5 glass fiber. In order to obtain the emission from glass, rare-earth ions are introduced into the glassy structure. Every lanthanide has its specific luminescence spectrum and it enables signal measurements at certain wavelengths according to electron transitions of metal ions. It is useful in case of increasing the sensitivity and the direct measurements of the changing signal. Among lanthanide ions, the samarium (Sm3+) is one of interesting to analyze the fluorescence properties due to relatively high quantum efficiency given by -1 4 6 wide energy gap (ΔE = 7000 cm ) between the G5/2 emitting level and the underlying F11/2 level [9, 10]. Also, the strong absorbance band at the wavelength of 405 nm allows to effective excitation of glass by commercial laser diodes and then the emission in the visible range (orange color) which is easy to measure by Si photodetector. These factors lead to the reduction of measurement setup cost and simplify analysis of results. Besides, samarium ions are widely used in photonic sensors [11, 12] or in other medical applications [13-15]. This paper presents an interesting new opportunity to determine degradation process in bioactive glass fibers. In situ measurements of luminescence intensity were possible to observe by doping the bioglass fibers with samarium ions, characterized by strong emission in the visible range. Due to progressive luminescence signal scattering, it could be Photonics Applications in Astronomy, Communications, Industry, and High-Energy Physics Experiments 2018, edited by Ryszard S. Romaniuk, Maciej Linczuk, Proc. of SPIE Vol. 10808, 1080833 © 2018 SPIE · CCC code: 0277-786X/18/$18 · doi: 10.1117/12.2500274 Proc. of SPIE Vol. 10808 1080833-1 Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 10/3/2018 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use found that bioactive glass fiber fast degraded in Sorenson buffer by 24 hours. Also, the speed of reaction confirms excellent chemical properties of a glass composition which allow to the overall degradation of glass after the introduction to the human body. 2. EXPERIMENT The Bioglass 45S5 with molar composition of 45.6SiO2 – 24.4Na2O - 26.9CaO - 2.6P2O5 - 0.5Sm2O3 doped with the 0.5mol%. Sm2O3 was prepared by a conventional melt quenching technique. Reagents of 99.99% purity were used. A homogenized set (30g) was placed in a platinum crucible and melted in an electric furnace at the temperature of 1400 °C and oxide atmosphere for 60 min. Next, due to the high tendency to crystallization, the 45S5 glass fibers were fabricated by hand-drawn technique from the glass melt. This method was proposed by Crupper et. al. [16]. Biodegradation test was carried out by immersing the single glass fiber (100µm diameter) in 7.4 pH Sorenson’s buffer. This pH level corresponds to pH of human plasma. The fluid was kept at the temperature of 37°C for 24 hours. The fiber ends were out of fluid, this enabled continuous measurement of luminescence signal without disturbing the system. The interaction length was approx. 40 mm. Samarium doped fiber was excited directly from his forehead by a laser diode (100mW, CW) generated at the wavelength of 405nm (fig 1). The luminescence signal was collected at the end of the fiber by Stellarnet GreenWave spectrometer in the range of 500-750 nm with 0.5 nm resolution. In the beginning, measurements were recorded in every 15 minutes for the first 4 hours, then after each next hour. In figure 1, the simplified measurement scheme was presented. The polypropylene container with Sorenson’s buffer and bioglass fiber was placed on the heating plate with adjustable temperature and a thermocouple. Automatic feedback allowed the regulation and stabilization of the liquid temperature throughout the whole research time. thermocouple 37 °C Sorensen's buffer \A/ \T/ luminescence 45S5_05Sm bioactive glass n =1.48 J laser n=1.33 tttttt heat Fig. 1. The scheme of biodegradation measurements set up. 3. RESULTS AND DISCUSSION 3.1. Absorbance spectra Figure 2 shows the comparison of absorbance spectra of 45S5 glass doped with Sm3+ ions in initial conditions and after 24h of degradation. In the analyzed spectral range, four absorption bands were observed at the wavelengths of 363 nm, Proc. of SPIE Vol. 10808 1080833-2 Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 10/3/2018 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use 4 6 6 4 376 nm, 404 nm and 465 nm assigned to D3/2, P7/2, P3/2 and I11/2 energy levels, respectively. The absorbance band at 404 nm has been used for effective excitation of samarium doped glass with the radiation of the laser diode (λexc=405 nm). It worth to noticed that after 24 houurs of degradation, the increase of absorbance level at the UV edge was occurred (blue line). This phenomenon is associated with higher scattering of the optical radiation due to partial degradation of the glass surface. 4 D3/2 8 6 P]n P32 N_ 325 3150 375 400 42'.5 450 475 500 wavelength [nm] Fig. 2. Absorbance spectra of 45S5 glass samples as melted (red line) and after 24h of degradation in SBF(blue line). 3.2 Luminescence spectra 3+ The luminescence spectra of fabricated glass fiber doped with Sm ions were shown in figure 3a. In the range of 500 - 750 nm, four characteristic emission bands at the wavelengths of 562 nm, 601 nm, 648 nm and 706 nm were observed. 4 6 4 6 4 6 4 6 at the. They are associated with the radiative transition G5/2 → H5/2, G5/2→ H7/2, G5/2→ H9/2 and 706 nm G5/2→ H11/2 respectively [10]. Strong decrease in emission intensity from fiber was observed during 24 hours of measurement. 6 Ä P3f2 2700 (a) 4G5/2 6 4.5S5 05Sm Oh (b) 4.5S5 o5Smzar d1(913)/2 + QM 2400 3 2100 W 1800 4 ti1500 fG6/2 -> 6H9/2 EE E C C C N M n CO VO CD 405 nm CD n 1200 709 (D U) ti E 900 4G5/2-> 6H_5/2 Oo 6F3 600 300 4G5/2 -> 6H11/2 0 f' \. i i i O 500 52(0 560 560 580 600 620 640 660 68C1 700 720 7 A.[nnn] 3+ 3+ Fig. 3. Luminescence spectra (a) of the Bioglass® doped with Sm , λp = 405nm and (b) simplified energy level diagram of Sm ion. Proc. of SPIE Vol. 10808 1080833-3 Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 10/3/2018 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use 4 After the excitation of 45S5 glass fibers, the metastable G5/2 level is populated via fast multiphonon relaxation process 6 4 4 from excited P3/2 level through I11/2+ M15/2 multiplets. Due to complex nature of ground state levels of samarium ions different quenching emission channels occurs. Strong luminescence signal at 601 nm and 648 nm were used to analyze degradation of fabricated glass fiber.

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