RESUMEN
As a kind of temperature-responsive hydrogel, polystyrene-co-poly(N-isopropylacrylamide)/poly(N-isopropylacrylamide) (PS-co-PNIPAM/PNIPAM) core-shell nanoparticles prepared by two-step copolymerization are widely studied and used because of their specific structures and properties. Unlike most reports about the steady stability of PS-co-PNIPAM/PNIPAM core-shell nanoparticle hydrogel emulsion, in this work, the PS-co-PNIPAM/PNIPAM core-shell nanoparticle hydrogel emulsion (symbolized as PS/PNIPAM hydrogel emulsion), which is prepared after the second step of synthesis and without washing out a large number of PNIPAM polymer segments, shows a reversible temperature-dependent sol-gel transition characteristic during the temperature range of 34-80 °C. The PS/PNIPAM hydrogel emulsion is a normal solution at room temperature, and it changes from a sol to a gel statue when the temperature approaches up to low critical solution temperature (LCST). As the temperature continues to increase, the gel (core-shell nanoparticles as the crosslinkers and the linear PNIPAM chain as the 3D gel network) of the PS/PNIPAM hydrogel emulsion gradually shrinks and drains linearly. Compared with most crosslinked hydrogels, the hydrogel here can be arbitrarily changed in shape according to use needs, which is convenient for use, transportation, and storage. Here a new route is provided for the preparation of a PS/PNIPAM core-shell hydrogel nanoparticle system, as well as a new supramolecular crosslinking sol-gel system for application in biomedical materials, sensors, biological separation, drug release, macromolecular adsorption, and purification.
Asunto(s)
Hidrogeles , Nanopartículas , Resinas Acrílicas , Emulsiones , Poliestirenos , TemperaturaRESUMEN
PURPOSE: We investigated the function of the recurrent laryngeal nerve (RLN) in a live porcine model during adjacent activation with bipolar forceps (BF), LigaSure small jaw (LSJ), Sonicision and PlasmaBlade (PB) devices. METHODS: Each of the energy-based devices (EBD) was activated for 3 seconds at different power settings at 5, 3, 2, and 1 mm from the RLN. Nerve root function and thermal spread were measured by continuous intraoperative neuromonitoring and infrared thermal imaging. RESULTS: BF: The EMG amplitude decreased to 87% of baseline at a standardized distance. The highest thermal reading was 120°C at 1 mm (average 80.7°C). LSJ: EMG amplitudes were 99% (5mm), 90% (3mm) and 66% (2mm) of the baseline amplitude. At 1mm, the temperatures of the RLN surface and the LSJ tip reached 80.6°C and 100.8°C, respectively. Sonicision: Under both the minimum and maximum settings, EMG amplitudes remained above 80% of the baseline amplitude. The highest temperatures of the device tip and RLN surface were 135°C and 117.3°C, respectively, at 1 mm. PB: The temperatures of the device tip and RLN surface increased gradually with an increase in the setting (tip 38.3°C to 163.8°C; nerve 34.8°C to 46.2°C). Loss of nerve function occurred at settings 9 and 10. There were no changes in the latency profile under any of the applications. CONCLUSIONS: RLN roots were exposed to increased temperatures when EBDs were applied at close spacing. The results suggest that these 4 EBDs are unsafe when applied at a distance of 1-3 mm from the RLN due to their effects on both EMG and temperature.
RESUMEN
A type of dual-emission probe with highly recognizable luminescence-response to pH has been designed. For the prepared core-shell polymeric hydrogel nanoparticles probe (Eu(DBM)3Phen doped polystyrene (PS)-co-poly(N-isopropylacrylamide)(PNIPAM)/FITC), the red emission of inner encapsulated europium complexes Eu(DBM)3Phen is remained in the hydrophobic PS core and used as a stable reference signal. Comparingly, the green emission of outer electrostatic bonded fluorescent isothiocyanate (FITC) moieties on the hydrophilic PNIPAM shell is adjusted and acted linear and reversible luminescence-response to pH between 5.8 and 7.4 with an exact resolution of 0.1 units. As a remarkable and smart pH probe, the hydrogel nanoparticles show low biological toxicity and prolonged resistance to ions and photobleaching. Also, the probes have successfully discriminated the fluorescent imaging for cytoplasmic matrix based on different pH with minimum biologic background fluorescence. These dual-emission pH-sensitive hydrogel nanoparticles suggest potential applications in clinical medicine, such as cell imaging and disease diagnosis.