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International Journal of Bioprinting DEX-Loaded PLGA microspheres enhance cartilage regeneration

Figure 2. Characterization and analysis of PLGA-dex60, PLGA-dex30, PLGA-dex15, and PLGA-dex0 microspheres: SEM, pore size, FTIR, XRD, TGA,
DTG, and DSC results. (A–D) Scanning electron microscopy (SEM) images of the structures of PLGA-dex60 MPs (A), PLGA-dex30 MPs (B), PLGA-dex15
MPs (C), and PLGA-dex0 MPs (D). (E) Distributions of pore sizes and average pore sizes of various groups of PLGA MPs. (F) Fourier transform infrared
spectroscopy (FTIR) results of various groups of PLGA MPs. (G) X-ray diffraction (XRD) pattern of various groups of PLGA MPs. (H) Thermogravimetric
analysis (TGA) results of various groups of PLGA MPs. (I) Derivative thermogravimetric analysis (DTG) results of various groups of PLGA MPs. (J)
Differential scanning calorimeter (DSC) curves and (K) distribution of weight average molecular weight changes.

of PLGA was observed between 1750 and 1755 cm , X-ray crystallographic (XRD) analysis was conducted to
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while that of DEX appeared between 1650 and 1660 cm . investigate potential alterations in the crystalline structure
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Given the potential overlap of DEX’s carbonyl peak with of the drug, thereby exploring the crystalline properties of
PLGA’s C=O peak, the intensity of PLGA’s C=O stretching DEX within the MPs. As illustrated in Figure 2G, the XRD
vibration peak may decrease with increasing DEX loading. spectra of the four groups of PLGA MPs displayed broad
After physical mixing of PLGA with DEX, the C=O and diffuse non-crystalline diffraction peaks, indicating
stretching vibration peak of DEX remained discernible, the presence of characteristic peaks of the drug DEX in the
and its intensity increased proportionally with the rise in XRD spectra of drug-loaded MPs. This suggests that DEX
drug loading. This intensity augmentation correlated with in the MPs adopts an amorphous structure or lacks a long-
the concentration of DEX in the MPs, almost disappearing range periodic arrangement, predominantly existing in
relative to blank MPs. an amorphous state. Notably, no significant characteristic

Volume 10 Issue 5 (2024) 389 doi: 10.36922/ijb.3396