ABSTRACT
Surface and interface modifications of synthetic silicone hydrogels used for wearable and implantable medical devices, e.g. catheters and contact lenses, are critical to overcome their poor mechanical properties and biofouling. In this paper, silica nanoparticles (SiO2 NPs) were incorporated within silicone hydrogels through photo-polymerization. As compared to the silicone hydrogel, the nanocomposited silicone hydrogel shows highly textured microstructures, increased swelling behaviour and improved stiffness. Meanwhile, a hydrophilic surface of silicone hydrogel is important to minimize protein fouling which forms a conditioning layer for the growth of bacterial biofilm. Here, we applied matrix-assisted pulsed laser evaporation (MAPLE) with a pulsed Nd:YAG laser at 532 nm to deposit polyethylene glycol (PEG) on the surface of the nanocomposited silicone hydrogels. The PEG deposited on the nanocomposited silicone hydrogels forms islands at the submicron-scale, which increase with increasing irradiation time (t). The protein adsorption on nanocomposited silicone hydrogel with PEG deposition decreases over 40 ± 2% when t = 2 h. Compared to the commercial silicone catheters, the nanocomposited silicone hydrogel with PEG deposition can reduce the growth of bacteria from 1.20 × 106 CFU cm-2 to 3.69 × 105 CFU cm-2. In addition, the relative cell viabilities of NIH/3T3 mouse fibroblast cells treated using the nanocomposited silicone hydrogels coated with/without PEG were studied. No toxic effect is imposed on the cells. Consequently, the MAPLE process is a controllable, contamination-free technique to modify the surface of silicone hydrogels. We expect that the nanocomposited silicone hydrogels with appropriate surface treatment can be applied in various wearable and implantable medical devices.
ABSTRACT
OBJECTIVE: Drug adherence is crucial to the success of highly active antiretroviral therapy (HAART) in the treatment of HIV disease. Adherence to HAART and its determinants may, however, differ across HIV/AIDS populations. METHODS: We retrospectively studied drug adherence by self-report in HIV-1 infected Chinese patients who have been on HAART for at least 1 year as at the end of year 2000. HAART is defined as three or more antiretrovirals with at least one protease inhibitor or non-nucleoside analogue reverse transcriptase inhibitor. RESULTS: The last drug adherence level assessed by self-report in 161 Chinese patients were: grade A (100%) - 130, 80.7%; grade B (95-99%) - 25, 15.5%; grade C (90-94%) - three, 1.9% and grade D (< 90%) - three, 1.9%. Patients with full adherence were more likely to have undetectable (< 500 copies/mL) plasma virus level (adjusted OR, 4.22; 95% CI, 1.75-12.33). Patients' demographics, HIV disease status and antiretroviral regimen did not affect adherence. Partial drug adherence was, however, independently associated with the psychosocial factors of missing clinic appointments (adjusted OR, 3.13; 95% CI, 1.23-8.33), forgetfulness (adjusted OR, 4.55; 95% CI, 1.64-12.5) and a busy work life (adjusted OR, 6.67; 95% CI, 1.75-25). CONCLUSION: There were similarities and differences in determinants affecting HAART adherence in Chinese compared with other patients. Psychosocial factors rather than HIV disease or treatment were more important factors in our Chinese patients. The relevance of patient populations and care setting for adherence to HAART shall be further studied.
