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In a previous study, we demonstrated the feasibility of retaining poly(N-isopropylacrylamide) (pNIPAAm) on hydroxylated surfaces by spin-coating a blend of pNIPAAm with a small amount of 3-aminopropyltriethoxysilane (APTES), an organosilane, followed by thermal annealing. In this study, we detail the conditions for retaining pNIPAAm films by APTES. Our results show that the difference in surface energy between pNIPAAm and APTES in the blended film resulted in the segregation of APTES molecules to the film/substrate interface, as verified by XPS, during annealing, and the segregated APTES molecules cross-linked to form the APTES network, thus entrapping pNIPAAm. The retained pNIPAAm films (25–35 nm) exhibited thermo-responsive behavior, determined by water contact angles and film thickness in water at temperatures above and below the lower critical solution temperature of pNIPAAm, as well as good cell attachment and rapid detachment (<10 minutes). The gained insights would allow a better design of these thermo-responsive surfaces for cell sheet engineering and other relevant applications.

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Objectives:To assess Saudi mother’s preferences regarding Saudi children’s physicians’ attire, and its influence on the parents’ level of trust and confidence.Methods:A cross-sectional survey was conducted from January to April 2014. Our sample comprised mothers of pediatric patients in both inpatient and outpatient settings at National Guard Hospital, Riyadh, Kingdom of Saudi Arabia. Mothers answered multiple questions, including their preferences regarding male and female pediatric physicians’ attire, their preferences regarding their children’s physician’s gender, and the impact of physician’s appearance on mothers’ confidence.Results:There were 259 female participants. Of all caregivers, 51.4% were 32-years-old or younger. Of those, 170 (65.6%) were educated (had completed high school or higher). Forty-four percent preferred that male physicians wear scrubs, while 5.4% preferred formal attire (tie, shirt, and trousers) and 27.8% preferred Saudi national attire (Thobe and shemagh). Most caregivers (57.9%) preferred that female physicians wear long skirts. Most caregivers (87.6%) preferred physicians to wear a white coat. Most (89.2%) believed that a physician’s appearance is very important.Conclusion:Gender of the treating physician is insignificant to mothers. However, the level of trust in a physician is related to his/her external appearance. Most mothers prefer their children’s physicians to wear scrubs.

A negatively charged hydrophilic low fouling film was prepared by thermally cross-linking a blend consisting of polystyrene sulfonic acid (PSS) and polyethylene glycol (PEG). The film was found to be stable by dip-washing. The fouling resistance of this material towards bacterial (Escherichia coli) and colloidal (polystyrene particles) attachment, non-specific protein (fibronectin) adsorption and cell (3T3 NIH) adhesion was evaluated and was compared with glass slides modified with polyethylene glycol (PEG) brushes, oxidized 3-mercaptopropyltrimethoxysilane (sulfonic acid, SA), and n-octadecyltrichlorosilane (OTS). The extended Derjaguin-Landau- Verwey-Overbeek (XDLVO) theory and thermodynamic models based on surface energy were used to explain the interaction behaviors of E. coli/polystyrene particles–substrate and protein–substrate interactions, respectively. The cross-linked PSS-PEG film was found to be slightly better than SA and PEG towards resisting non-specific protein adsorption, and showed comparable low attachment results as those of PEG towards particle, bacterial and NIH-3T3 cells adhesion. The low-fouling performance of PSS-PEG, a cross-linked film by a simple thermal curing process, could allow this material to be used for applications in aqueous environments, where most low fouling hydrophilic polymers, such as PSS or PEG, could not be easily retained.

Silane coupling agents are commonly employed to link an organic polymer to an inorganic substrate. One of the widely utilized coupling agents is 3-aminopropyltriethoxy silane (APTES). In this study, the authors investigated the ability of APTES to retain thermo-responsive poly(N-isopropylacrylamide) (pNIPAAm) on hydroxylated surfaces such as glass. For comparison purposes, the authors also evaluated the retention behaviors of (1) polystyrene, which likely has weaker van der Waals interactions and acid-base interactions (contributed by hydrogen-bonding) with APTES, on APTES as well as (2) pNIPAAm on two other silane coupling agents, which have similar structures to APTES, but exhibit less interaction with pNIPAAm. Under our processing conditions, the stronger interactions, particularly hydrogen bonding, between pNIPAAm and APTES were found to contribute substantially to the retention of pNIPAAm on the APTES modified surface, especially on the cured APTES layer when the interpenetration was minimal or nonexistent. On the noncured APTES layer, the formation of an APTES-pNIPAAm interpenetrating network resulted in the retention of thicker pNIPAAm films. As demonstrated by water contact angles [i.e., 7 -15 higher at 40 C, the temperature above the lower critical solution temperature (LCST) of 32 C for pNIPAAm, as compared to those at 25 C] and cell attachment and detachment behaviors (i.e., attached/spread at 37 C, above LCST; detached at 20 C, below LCST), the retained pNIPAAm layer (6-15 nm), on both noncured and cured APTES, exhibited thermo-responsive behavior. The results in this study illustrate the simplicity of using the coupling/adhesion promoting ability of APTES to retain pNIPAAm films on hydroxylated substrates, which exhibit faster cell sheet detachment ( 30 min) as compared to pNIPAAm brushes (in hours) prepared using tedious and costly grafting approaches. The use of adhesion promoters to retain pNIPAAm provides an affordable alternative to current thermo-responsive supports for cell sheet engineering and stem cell therapy applications.

This study explored the possibility of polymer interdiffusion for retaining thermoresponsive poly(N-isopropylacrylamide) (pNIPAAm) on polycarbonate (PC). It was hypothesized that interdiffusion could be facilitated either by increasing the annealing temperature or by treating PC using air plasma (AP) and ultraviolet ozone (UVO). The results showed that increasing annealing temperature only moderately improved pNIPAAm retention. Treating PC with AP led to an increase in surface-active groups and a greatly enhanced retention of pNIPAAm. UVO treatment, however, severely damaged the PC layer with no noticeable enhancement on pNIPAAm retention. The retained pNIPAAm films on PC exhibited thermoresponsive behavior as evidenced by water contact angle and desired cell attachment/detachment behaviors. These results illustrate the simplicity of using polymer interdiffusion to successfully retain pNIPAAm films on a polymer, and the resulting substrates would be less expensive and more versatile than those retained on brittle supports (e.g., glass) for applications that require resilient thermoresponsive substrates.

Zosteric acid (ZA), a bioactive component in Zostera marina eelgrass, was applied to assess closure of normal mouse fibroblast scratch and collagen I expression. The cytotoxicity of ZA on the fibroblast at different ZA concentrations was evaluated. ZA showed low toxicity with ~80% of cell viability at a concentration of ~1600 ppm. A single scratch (~1500 μm) was made on a layer of fibroblast, and collagen expression was determined after 72 hours when the scratch fully closed for both ZA-treated and untreated samples. Compared to control, the ZA-treated cells were slightly less dense and randomly oriented in the closure region and had lower actin and vinculin expressions. The total collagen expressions were comparable to the control, whereas collagen I expression of the mouse fibroblast treated with 1600 ppm of ZA was significantly lower than untreated fibroblasts.