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We have developed L-glutamic acid (LG) loaded chitosan (CS) hydrogels to treat diabetic wounds. Although literature reports wound healing effects of poly(glutamic acid)-based materials, there are no studies on the potential of L-glutamic acid in treating diabetic wounds. As LG is a direct precursor for proline synthesis, which is crucial for collagen synthesis, we have prepared CS + LG hydrogels to accelerate diabetic wound healing. Physiochemical properties of the CS + LG hydrogels showed good swelling, thermal stability, smooth surface morphology, and controlled biodegradation. The addition of LG to CS hydrogels did not alter their biocompatibility significantly. CS + LG hydrogel treatment showed rapid wound contraction compared to control and chitosan hydrogel. Period of epithelialization is significantly reduced in CS + LG hydrogel treated wounds (16 days) compared to CS hydrogel (20 days), and control (26 days). Collagen synthesis and crosslinking are also significantly improved in CS + LG hydrogel treated diabetic rats. Histopathology and immunohistochemistry results revealed that the CS + LG hydrogel dressing accelerated vascularization and macrophage recruitment to enhance diabetic wound healing. These results demonstrate that incorporation of LG can improve collagen deposition, and vascularization, and aid in faster tissue regeneration. Therefore, CS + LG hydrogels could be an effective wound dressing used to treat diabetic wounds.

The depletion of alkylamine terminal groups at the vacuum-polymer interface is measured for a,@-difunctional poly(dimethylsi1oxane) oligomers by X-ray photoelectron spectroscopy. The driving force for this depletion is the high relative surface energy of the amine terminal groups compared to that of the low surface energy poly(dimethylsi1oxane) backbone. The degree of surface end group depletion, within the maximum sampling depth probed (ca. 7 nm), is found to be on the order of 40% for a 960 molecular weight oligomer and decreases slightly with an increase in the oligomer molecular weight. Angle-dependent measurements are applied to determine end-group concentration depth profiles. End-group depletion is largest at the shallowest sampling depths and decays rapidly toward the bulk. The decay profiles cannot be explained by simple monotonic decay functions, consistent with the expected effects of connectivity between the end groups and the chain backbone, but the data are insufficient to prove whether the profiles are oscillatory in nature, as expected from theoretical considerations.

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Near infrared (NIR) light utilization in a range of current technologies has gained huge significance due to its abundance in nature and nondestructive properties. NIR active lanthanide (Ln) doped upconversion nanomaterials synthesized in controlled shape, size, and surface functionality can be combined with various pertinent materials for extensive applications in diverse fields. Upconversion nanophosphors (UCNP) possess unique abilities, such as deep tissue penetration, enhanced photostability, low toxicity, sharp emission peaks, long anti-Stokes shift, etc., which have bestowed them with prodigious advantages over other conventional luminescent materials. As new generation fluorophores, UCNP have found a wide range of applications in various fields. In this Review, a comprehensive overview of lanthanide doped NIR active UCNP is provided by discussing the fundamental concepts including the different mechanisms proposed for explaining the upconversion processes, followed by the different strategies employed for the synthesis of these materials, and finally the technological applications of UCNP, mainly in the fields of bioimaging, drug delivery, sensing, and photocatalysis by highlighting the recent works in these areas. In addition, a brief note on the applications of UCNP in other fields is also provided along with the summary and future perspectives of these materials.