Ocular antibacterial chitosan-maleic acid hydrogels: In vitro and in vivo studies for a promising approach with enhanced mucoadhesion

On-demand dual-stimuli-responsive hydrogels for localized and sustained delivery of MP-L [I5R8] to treat bacterial wound infections

This study presents the development of two novel injectable dual-responsive polyanionic hydrogels (DRPHs) based on N-isopropylacrylamide (NIPAM), incorporating carboxylic acid comonomers for temperature- and pH-responsive drug release. These hydrogels were designed for the sustained and localized delivery of the antimicrobial peptide MP-L [I5R8], targeting multidrug-resistant bacteria (MDRB) in wound infections. The physicochemical characterization confirmed polymer formation and comonomer integration through Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Rheological analysis demonstrated a temperature-dependent sol-gel transition at ∼35°C, making the hydrogels suitable for in situ gelation at physiological conditions. The hydrogels exhibited tunable swelling behavior and a controlled dual-phase release profile of MP-L [I5R8], ensuring both immediate bactericidal activity and prolonged antimicrobial effect. In vitro assays confirmed sustained antimicrobial efficacy against Staphylococcus aureus and Pseudomonas aeruginosa, while biocompatibility tests validated their safety for biomedical applications. An in vivo diabetic wound infection model demonstrated rapid infection clearance, enhanced wound healing, and organized tissue regeneration following treatment with MP-L [I5R8]-loaded DRPHs. These results highlight the potential of dual-stimuli-responsive hydrogels as a next-generation antimicrobial delivery platform for the treatment of chronic infected wounds, such as diabetic foot ulcers.

Antibacterial Lecithin/Chitosan Nanoparticles for the Sustained Release of Ciprofloxacin to Treat Ocular Bacterial Infections

Ocular drug-delivery is one of the most challenging areas owing to nature of ocular tissues. Various nanoformulations have been designed and investigated for drug-delivery to achieve high drug bioavailability. The major focus of these preparations available in market is to utilize nanomaterial as drug-carrier only, with less focus on developing functional-nanomaterials, which is a key knowledge gap in the field. To address this, we developed a nanoparticulate system from bioactive-polymers, having intrinsic antimicrobial and mucoadhesiveness, loaded with ciprofloxacin (cipro) to treat ocular bacterial infections. Cipro-loaded lecithin/chitosan nanoparticles were prepared and characterized for their physiochemical properties. They exhibited good drug loading efficiency and showed sustained drug-release for 72 h, with slow release for first 4 h followed by a burst release in phosphate buffered saline and simulated tear fluid. Cipro-loaded nanoparticles were assessed for their antibacterial potential against Staphylococcus aureus (96 %) and Pseudomonas aeruginosa (72 %) using optical density, disc-diffusion method, live-dead assay, and demonstrated promising antibacterial properties. The drug-loaded nanoparticles showed good cytocompatibility (~90 %) towards murine fibroblasts and rabbit corneal cells. Being amphiphilic in nature, the nanoparticles exhibited mucoadhesiveness, hemocompatibility (<4 %) and, thus, proving to be a promising candidate for treating ocular infections. This approach ensures efficient drug delivery and synergic/additive therapeutic effects.

Development and Evaluation of the Biological Activities of a Plain Mucoadhesive Hydrogel as a Potential Vehicle for Oral Mucosal Drug Delivery

This study aimed to develop HGs based on cationic guar gum (CGG), polyethylene glycol (PEG), propylene glycol (PG), and citric acid (CA) using a 2k factorial experimental design to optimize their properties. HGs were characterized through FTIR and Raman spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The biological activities of HGs were determined by evaluating their mucoadhesive capacity and antibacterial activity in vitro, whereas their toxicity was analyzed using Artemia salina nauplii as an in vivo model. Results revealed that HGs were successfully optimized for their viscosity, pH, and sensory properties, and it was observed that varying concentrations of PEG-75 did not influence them. Through SEM analyses, it was noted that increased levels of PEG-75 resulted in HGs with distinct porosity and textures, whereas FTIR and Raman spectroscopy exhibited representative peaks of the raw materials used during the synthesis process. TGA studies indicated the thermal stability of HGs, as they presented degradation patterns at 100 and 300 °C. The synthesized HGs exhibited similar mucoadhesion kinetic profiles, demonstrating a displacement factor at an equilibrium of 0.57 mm/mg at 5 min. The antibacterial activity of HGs was appraised as poor against Gram-positive and Gram-negative bacteria due to their MIC90 values (>500 μg/mL). Regarding A. salina, treatment with HGs neither decreased their viability nor induced morphological changes. The obtained results suggest the suitability of CGG/PEG HGs for oral mucosa drug delivery and expand the knowledge about their mucoadhesive capacity, antibacterial potential, and in vivo biocompatibility.

Phosphatase-degradable nanoparticles providing sustained drug release

AIM

The study aimed to develop enzyme-degradable nanoparticles comprising polyphosphates and metal cations providing sustained release of the antibacterial drug ethacridine (ETH).

METHODS

Calcium polyphosphate (Ca-PP), zinc polyphosphate (Zn-PP) and iron polyphosphate nanoparticles (Fe-PP NPs) were prepared by co-precipitation of sodium polyphosphate with cations and ETH. Developed nanocarriers were characterized regarding particle size, PDI, zeta potential, encapsulation efficiency and drug loading. Toxicological profile of nanocarriers was assessed via hemolysis assay and cell viability on human blood erythrocytes and HEK-293 cells, respectively. The enzymatic degradation of NPs was evaluated in presence of alkaline phosphatase (ALP) monitoring the release of monophosphate, shift in zeta potential and particle size as well as drug release. The antibacterial efficacy against Escherichia coli was determined via microdilution assay.

RESULTS

NPs were obtained in a size range between 300 - 480 nm displaying negative zeta potential values. Encapsulation efficiency was in the range of 83.73 %- 95.99 %. Hemolysis assay underlined sufficient compatibility of NPs with blood cells, whereas drug and NPs showed a concentration dependent effect on HEK-293 cells viability. Ca- and Zn-PP NPs exhibited remarkable changes in zeta potential, particle size, monophosphate and drug release upon incubation with ALP, compared to Fe-PP NPs showing only minor differences. The released ETH from Ca- and Zn-PP nanocarriers retained the antibacterial activity against E. coli, whereas no antibacterial effect was observed with Fe-PP NPs.

CONCLUSION

Polyphosphate nanoparticles cross-linked with divalent cations and ETH hold promise for sustained drug delivery triggered by ALP for parental administration.