Finding a suitable biomaterial for scaffolding in cartilage tissue engineering has proved to be far from trivial. Nonetheless, it is clear that biomimetic approaches based on gelatin (Gel) and hyaluronic acid (HA) have particular promise. Herein, a set of formulations consisting of photo-polymerizable Gel; photo-polymerizable HA, and allogenic decellularized cartilage matrix (DCM), is synthesized and characterized. The novelty of this study lies particularly in the choice of DCM, which was harvested from an abnormal porcine with α-1,3-galactose gene knockout. The hybrid hydrogels were prepared and studied extensively, by spectroscopic methods, for their capacity to imbibe water, for their behavior under compression, and to characterize microstructure. Subsequently, the effects of the hydrogels on contacting cells (in vitro) were studied, i.e., cytotoxicity, morphology, and differentiation through monitoring the specific markers ACAN, Sox9, Coll2, and Col2α1, hypertrophy through monitoring the specific markers alkaline phosphatase (ALP) and Col 10A1. In vivo performance of the hydrogels was assessed in a rat knee cartilage defect model. The new data expand our understanding of hydrogels built of Gel and HA, since they reveal that a significant augmenting role can be played by DCM. The data strongly suggest that further experimentation in larger cartilage-defect animal models is worthwhile and has potential utility for tissue engineering and regenerative medicine.

The widespread antibiotic resistance has called for alternative antimicrobial agents. Carbon nanomaterials, especially carbon quantum dots (CQDs), may be promising alternatives due to their desirable physicochemical properties and potential antimicrobial activity, but their antimicrobial mechanism remains to be investigated. In this study, nitrogen-doped carbon quantum dots (N-CQDs) were synthesized to inactivate antibiotic-resistant bacteria and treat bacterial keratitis. N-CQDs synthesized via a facile hydrothermal approach displayed a uniform particle size of less than 10 nm, featuring a graphitic carbon structure and functional groups including -OH and -NH₂. The N-CQDs demonstrated antimicrobial activity against Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus, which was both dose- and time-dependent, reducing the survival rate to below 1 %. The antimicrobial activity was confirmed by live/dead staining. In in vivo studies, the N-CQDs were more efficient in treating drug-resistant bacterial keratitis and reducing corneal damage compared to the common antibiotic levofloxacin. The N-CQDs were shown to generate intracellular and extracellular ROS, which potentially caused oxidative stress, membrane disruption, and cell death. This antimicrobial mechanism was supported by scanning and transmission electron microscopy, significant regulation of genes related to oxidative stress, and increased protein and lactate dehydrogenase leakage. This study has provided insight into the development, application, and mechanism of N-CQDs in antimicrobial applications.

Soft contact lenses are increasingly being explored as a vehicle for controlled delivery of ophthalmic drugs. However, traditional methods of drug-loading by soaking have limitations such as burst delivery and the release of drugs at the front side of the lens, leading to poor drug efficacy and systemic side effects. This study introduces a new methodology, termed asymmetric drug loading, whereby the ophthalmic drug ‘Rebamipide’ is attached to and released from the post-lens (=cornea-contacting) surface exclusively. The methodology involves using polymeric microparticles that carry a lipophilic crystalline ophthalmic drug at their surface. These drug-loaded microparticles first transfer the drug to the concave surface of the contact lens, and when worn, the drug is transferred again, now from the lens to the cornea. This is achieved through the diffusion of the drug from one hydrophobic microenvironment (the silicone moieties of the contact lens polymer network) to another hydrophobic microenvironment (the corneal epithelium) over a short pathway. The second drug transfer was observed and studied in experiments using an ex vivo porcine eye model. The results show that the drug amount that was absorbed by the cornea after applying the rebamipide-loaded contact lenses is approximately 3× (10.7 ± 3.1 μg) as much as the amount of rebamipide that gets transferred after the instillation of one eye drop (1% solution (p < 0.001). The new drug-loading method offers a practical and reproducible means of delivering ophthalmic drugs to the cornea through soft contact lenses. The drug payloads achieved are comparable to dosages used during eye drop therapy.