Based on the demonstrated and reported trypanocidal, leishmanicidal, and antiplasmodial activities of two menthol prodrugs, it was decided to proceed with preformulation studies, which are of key relevance in the drug discovery process. The aim of this study is to examine the stability and permeability of two new menthol prodrugs with antiparasitic activity. To determine the stability of menthol and its prodrugs, the corresponding studies were carried out in buffered solutions at pH values of 1.2, 5.8, and 7.4 at 37 °C. In silico permeability studies were performed using the free PerMM software and then in vitro permeability studies were performed using a biomimetic artificial membrane (BAM). Permeability studies conducted in silico predicted that both menthol and its prodrugs would pass through biological membranes via flip-flop movement. This prediction was subsequently confirmed by in vitro BAM permeability studies, where it was observed that the menthol prodrugs (1c and 1g) exhibited the highest P_app (apparent permeability) value compared to the parent compound. The study reveals that menthol prodrugs exhibit stability at a pH of 5.8 and possess sufficient in vitro permeability values as preformulation parameters.

The generation of organized 3D tissue constructs that combines cells and photo-crosslinkable biomaterials has been demonstrated using a variety of 3D bioprinting technologies. These technologies have inspired the application for "in situ" bioprinting, resulting on hand-held tools called "Biopens" that can transfer bioprinting capabilities directly into the hands of the surgeons. Here, we have developed and validated a biopen for ophthalmological applications, specifically for corneal stromal regeneration using photochemical corneal crosslinking (CXL), as well as for cell bioprinting and, potentially, for corneal wound healing. We used the biopen to CXL, but also for fast crosslinking processes. Cytotoxicity, cell viability and immunofluorescence experiments were performed with human corneal stroma keratocytes (HCK) loaded inside the proposed bioink compositions. Photochemical cross-linking was performed to evaluate the biopen bioprinting functionality for corneal wound closure in porcine eyes. A full-thickness penetrating incision, 5 mm in length parallel to the limbus and perpendicular to the corneal surface, was made in the enucleated porcine cornea. The mechanical properties of cornea are imitated by tuning the proposed (GelMA/PEGDA/PI) bioink composition and crosslinking parameters, which envisage the potential for being translated to a clinical environment to corneal wound closure.

Cutaneous wound healing is a complex biological process often impaired by bacterial infections, especially by Staphylococcus aureus. To address this, alginate (ALG)/chitosan (CS) polyelectrolyte multilayer (PEM) films incorporating alginate-coated silver nanoparticles (ALG–AgNPs) were fabricated by layer-by-layer self-assembly. The films exhibited a porous, layered morphology with homogeneous distribution of ALG–AgNPs, hydrophilic surfaces (contact angle ≈ 55°), a high swelling degree (~175%), and a water vapor transmission rate of 1830 g m⁻²·day⁻¹. Thermal analyses showed similar degradation profiles up to 600 °C, with the ALG–AgNP film displaying lower moisture loss and higher dehydration temperature, consistent with enhanced ionic and coordination crosslinking (–NH₃⁺/–COO⁻ and Ag–O–C bonds). The release of Ag⁺ in PBS (pH 7.4) was ~3% after 24 h, following a Korsmeyer–Peppas mechanism (R² = 0.97, n < 0.5), and degradation, with ~40% mass loss in 6 days, indicated gradual matrix disintegration. Cytocompatibility studies revealed >80% viability for fibroblasts, keratinocytes, macrophages, and 2-log reduction in adhesion, and an 11 ± 1 mm inhibition zone for S. aureus. These results demonstrate that ALG/CS–AgNP PEM films combine biocompatibility, antibacterial efficacy, controlled degradation, and structural stability, making them promising multifunctional scaffolds for the regeneration of infected skin wounds.

Bioprinting continues to redefine the frontiers of regenerative medicine by enabling the fabrication of complex, three-dimensional (3D) tissue constructs that emulate native biological and mechanical functions. However, despite significant progress, critical challenges remain, particularly in achieving precise multi-material integration, high-resolution patterning, and structural fidelity necessary for functional tissue engineering. A major limitation in ‘top–down’ vat photopolymerization bioprinting, especially digital light processing (DLP)-based approaches, lies in the precise control of layer thickness, a parameter that directly affects mechanical integrity, biological activity, and spatial resolution. This study presents a novel, automated platform designed to overcome one of the most persistent bottlenecks in multi-material top–down DLP bioprinting: the real-time, accurate measurement of the dynamic gap between the cured layer and the bioink surface. Through a comparative assessment of classical computer vision and deep learning (convolutional neural network-based) techniques, we demonstrate a system capable of achieving sub-0.1 mm precision (0.092 mm) with strong correlation to mechanical measurements ( R = 0.994). This vision-based system adapts to a wide range of bioinks with varying viscosities, opacities, and photopolymerization kinetics, eliminating the need for manual recalibration during material switching. As a demonstration of its capabilities, we successfully printed a multimaterial vascular-like tissue structure with high spatial fidelity across heterogeneous biomaterials. Further, we bioprinted a multimaterial skin tissue model, featuring compartmentalized dermal/bone analogs, to enable in vitro functional evaluation. These case studies highlight the platform’s potential to advance biofabrication workflows by improving reproducibility, material adaptability, and structural precision, paving the way toward clinically scalable tissue manufacturing systems.