Investigating long term storage stability and drug release behavior of polypeptide based fibrous scaffold for tissue engineering application.

Electrospun poly (γ-benzyl- l -glutamate) (PBG) scaffold felt with aligned fibers shows promising nerve regeneration and neurite growth capability due to the nerve stimulating moiety of glutamate in the PBG material. The nerve regeneration capability can be further enhanced by incorporating 4 wt% minocycline hydrochloride (MH) in the scaffold (PBGMH4). They are useful in the nerve tissue engineering to repair and regeneration damaged nerves in central nerve system or peripheral nerve system. Here we investigate the ambient storage capability of PBG and PBGMH4 by monitoring the changes over time of fiber dimension, mechanical properties of both scaffolds and amount of drug release of PBGMH4. It is interesting to observe the diameter of fibers and mechanical strength of scaffolds increases but the amount of drug release decrease with time. By carefully examining the top view of the scaffolds using scanning electron microscopy (SEM), the fiber diameter of PBG increased by 58 % over the 12 months storage period, which is larger than the 32 % increase observed for PBGMH4. Furthermore, after storage for 12 months, the difference in fiber diameter between the top and bottom sides of PBG scaffold is 25.9 %, whereas for PBGMH4 is only 6.3 %. These results demonstrate that the PBGMH4 scaffold exhibits superior storage stability compared to that of PBG. Because the fibers of the scaffolds are aligned without any crosslinkage, the scaffolds are porous structure of felts. The porosity of PBGMH4 scaffold is decreased from 90 % to 72 % which can be accountable for the decrease of drug release from initial 42 % to a stabilized 26 % after 9 months of storage. The results indicate the specific surface area of the scaffolds play an important role in governing drug release kinetics. This study thoroughly investigates the storage stability of PBG and PBGMH4 electrospun fibrous scaffolds. The observed correlations between fiber diameter, mechanical properties, and drug release behavior hold implications for the design of advanced bioscaffolds. The long shelf life of optimal PBGMH4 scaffold shows potential application for the nerve regeneration and controlled drug delivery systems. [Display omitted] • A systematically investigated storage stability and drug release behavior of polypeptide-based fibrous scaffold. • Gravity impact on PBG scaffold felt storage led to an increase in fiber diameter on the bottom side of the scaffold. • The tensile strength of both PBG and PBGMH4 scaffolds increases as the storage time increases. • PBGMH4 scaffolds exhibit superior storage stability due electrostatic repulsion from MH. • The specific surface area of the scaffold plays a critical role in controlling drug release kinetics. [ABSTRACT FROM AUTHOR]