Rational design and synthesis of novel heparan sulfate mimetic compounds as antiadhesive agents

Ag/Cu nanoparticles-loaded glycocalyx biomimetic corneal bandage lenses for combatting bacterial keratitis

Bacterial keratitis is a major cause of blindness, hindered by the rising threat of antibiotic resistance. Although corneal bandage lenses (CBLs) are widely utilized in ophthalmic treatment, their effectiveness in treating bacterial keratitis remains limited due to risks of secondary infections, patient discomfort, and complications. In this study, we developed a novel biomimetic coating on CBLs by grafting Ag/Cu bimetallic nanoparticles (Ag/Cu-NPs) and thiol-functionalized heparin (Hep-SH) using a rapid polydopamine (PDA) deposition technique, effectively mimicking the ocular surface glycocalyx structure. The resulting Ag/Cu-NPs/Hep-SH coated CBLs (PNH-CBLs) exhibited significant antibacterial activity, with over 80 % reduction in Staphylococcus aureus (S. aureus) and 70 % in Escherichia coli (E. coli) due to the sustained release of Ag+ and Cu2+, along with displaying favorable in vitro biocompatibility. Animal experiments conducted on New Zealand white rabbits with bacterial keratitis demonstrated successful treatment therapeutic outcomes, with PNH-CBLs leading to a significant decrease in clinical score. These biomimetic lenses also exhibited selective anti-protein adsorption properties, minimizing inflammation and promoting surface lubrication. Overall, this innovative approach addresses critical challenges in antibiotic resistance and offers a promising therapeutic strategy for managing ophthalmic infectious diseases.

Involvement of disulfide bond formation in the activation of heparanase

Heparanase is overexpressed in many solid tumor cells and is capable of specifically cleaving heparan sulfate, and this activity is associated with the metastatic potential of tumor cells; however, the activation mechanism of heparanase has remained unknown. In this study, we investigated the link between disulfide bond formation and the activation of heparanase in human tumor cells. Mass spectrometry analysis of heparanase purified from a conditioned medium of human fibrosarcoma cells revealed two disulfide bonds, Cys127-Cys179 and Cys437-Cys542, and one S-cysteinylation at the Cys211 residue. It was shown that, although the formation of the Cys127-Cys179 bond and S-cysteinylation at Cys211 have little effect on heparanase function, the disulfide bond between Cys437 and Cys542 is necessary for the secretion and activation of heparanase. Thus, the present findings will provide a basis for the further refinement of heparanase structural studies and for the development of novel heparanase inhibitors.