Effects of surface area to volume ratio of PLGA scaffolds with different architecture on scaffold degradation rate and drug release kinetics
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1
University of Texas Rio Grande Valley, Department of Health and Biomedical Sciences, United States
Introduction: Scaffolds with different architecture (i.e. globular, thick strand and thin strand) can be successfully fabricated through an easy and economical mold-less technique for controlled release of drugs. The size and architecture of these scaffolds can be easily tailored by the volume of material that is dispensed and method it is injected into an aqueous solution, respectively. In this work, PLGA scaffolds with different architecture were fabricated to investigate the effects of surface area to volume ratio (SVR) on scaffold degradation rate and drug release kinetics. It is hypothesized that a larger surface area will result in a higher degradation rate as there is higher buffer penetration which will lead to an increase in hydrolysis as water molecules can more easily access the esters in the polymer matrix. Furthermore, it is hypothesized that the drug release kinetics will also increase as a higher SVR polymeric matrix has more surface area for the encapsulated agents to diffuse out more rapidly.
Materials and Methods: Different delivery systems (micropipette attached to a 10-200 µL tip, micropipette attached to 100-1000 µL tip or a 1 mL plastic syringe for the globular, thick strand and thin strand scaffold, respectively) were used to inject 100 µL of PLGA/drug/tetraglycol solution into PBS to form the scaffolds. To determine the degradation rate of the scaffolds, the weight of lyophilized scaffolds were determined at each time point. For the release study, the amount of the model drug (i.e. minocycline) in the release solution was determined by measuring the absorbance at 350 nm.
Results: It was found that globular scaffolds resulted in the fastest degradation (83.2 ± 4.9% vs. 70.0 ± 4.3% and 60.7 ± 4.9% for the thick and thin strand scaffolds, respectively for PLGA 50:50 and 53.0 ± 1.8% vs. 24.1 ± 0.8 and 26.3 ± 1.8% for the thick and thin scaffold, respectively for PLGA 75:25). PLGA 50:50 resulted in more degradation compared to PLGA 75:25, as expected with the higher lactic to glycolic acid ratio. PLGA 50:50 globular scaffolds resulted in a biphasic release profile, with a burst release in the beginning and the middle of the release study.
Discussion: The globular scaffold, which had the lowest SVR, resulted in the fastest degradation rate which indicates that the degradation rate of the scaffold does not only depend on the SVR but also on other factors such as the retention of acidic degradation byproducts in the scaffold and scaffold porosity. A clear correlation between SVR and release rates was not observed, indicating that besides the availability of more surface area for drug to diffuse out of the polymer matrix, other factors such as scaffold degradation rate and scaffold porosity may play a role in determining drug release kinetics. PLGA 50:50 globular scaffold, which has a biphasic release profile, may be beneficial for some drug delivery applications.
Conclusion: There is a complex relationship between SVR, and the degradation rate and drug release kinetics of PLGA polymeric scaffolds investigated in this study as many other factors, such as the accumulation of acidic degradation byproducts in the scaffold and scaffold porosity, can play a role in determining the relationship between these factors. This mold-less fabrication technique is an easy and versatile approach, and thus, may be a promising method for the development of drug delivery scaffolds or composites.
Keywords:
Drug delivery,
biomaterial,
Scaffold,
Biodegradable material
Conference:
10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016.
Presentation Type:
Poster
Topic:
Biomaterials for therapeutic delivery
Citation:
Chew
S,
Arriaga
M and
Hinojosa
V
(2016). Effects of surface area to volume ratio of PLGA scaffolds with different architecture on scaffold degradation rate and drug release kinetics.
Front. Bioeng. Biotechnol.
Conference Abstract:
10th World Biomaterials Congress.
doi: 10.3389/conf.FBIOE.2016.01.02015
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Received:
27 Mar 2016;
Published Online:
30 Mar 2016.
*
Correspondence:
Dr. Sue Anne Chew, University of Texas Rio Grande Valley, Department of Health and Biomedical Sciences, Brownsville, TX, United States, sueanne.chew@utrgv.edu
Dr. Marco Arriaga, University of Texas Rio Grande Valley, Department of Health and Biomedical Sciences, Brownsville, TX, United States, marco.arriaga01@utrgv.edu
Dr. Victor Hinojosa, University of Texas Rio Grande Valley, Department of Health and Biomedical Sciences, Brownsville, TX, United States, victor.hinojosa01@utrgv.edu