Photoinduced chitosan-PEG hydrogels with long-term antibacterial properties.

Photochemical processes offer the possibility of preparing functional hydrogels under green conditions that are compatible with both synthetic and natural polymers. In this study, chitosan-based poly(ethylene) glycol (PEG) were successfully synthesized under light irradiation in aqueous medium. Kinetic studies under irradiation showed that less than 2 min were necessary to obtain fully cross-linked networks. Thermomechanical analyses and swelling experiments indicated that introduction of chitosan overall weakens the hydrogel network but can create domains of higher thermal stability than the PEG-alone structure. The resulting chitosan-PEG hydrogels demonstrated a tremendous inhibition (100%) of bacterial growth (Escherichia coli and Staphylococcus aureus). After 6 months' ageing, one of the hydrogels preserved a high antifouling activity against Escherichia coli. This interesting result, which could be correlated with the network features, demonstrates the strong potential of these photochemical methods to obtain robust bio-functional materials.

Eosin-mediated synthesis of polymer coatings combining photodynamic inactivation and antimicrobial properties.

Polymer coatings exhibiting photodynamic bacterial inactivation properties have been successfully engineered. Such coatings were obtained by photoinduced crosslinking of a PEG-diacrylate monomer associated with the eosin Y dye which was used as both a radical photoinitiator and an antibacterial agent. A dual curing process was followed by combining compatible and solvent-free polymerization mechanisms, i.e. Aza-Michael reaction and free-radical polymerization in the presence of amines. The kinetics evolution of the photopolymerization process was followed using in situ Fourier transform infrared spectroscopy, allowing for the elucidation of the underlying mechanistic pathways. The influence of eosin Y and amines on the thermal and mechanical properties of the films was evidenced and discussed in terms of crosslinking chemistry. The antibacterial properties of the coatings against two different strains (Escherichia coli and Staphylococcus aureus) were evaluated on short and long terms, revealing that eosin confers both photodynamic inactivation and antimicrobial properties to the films. These coatings are therefore particularly promising for disposable medical devices.

Determinants of direct-care staff turnover in group homes for individuals with mental retardation.

A model of direct-care human service staff turnover was proposed and tested with 236 direct-care staff members in nine private, nonprofit New Jersey agencies. A path analysis of the data was conducted. Four variables were found to contribute to current job satisfaction: agreement of the job with personal goals and values, burnout, satisfaction with supervision, and employment history. In turn, current job satisfaction led to intention to quit, which led to actual turnover. Implications for the human service field and future research were explored.