In this study, a novel class of multifunctional responsive nanoparticles is designed and fabricated as drug nanocarriers for synergetic chemo–photothermal therapy of tumors. The proposed nanoparticles are composed of a thermo-/pH-responsive poly­(N-isopropylacrylamide-co-acrylic acid) (PNA) nanogel core, a polydopamine (PDA) layer for photothermal conversion, and an outer folic acid (FA) layer as a targeting agent for the folate receptors on tumor cells. The fabricated nanoparticles show good biocompatibility and outstanding photothermal conversion efficiency. The proposed nanoparticles loaded with doxorubicin (DOX) drug molecules are stable under physiological conditions with low leakage of drugs, while rapidly release drugs in environments with low pH conditions and at high temperature. The experimental results show that the drug release process is mainly governed by Fickian diffusion. In vitro cell experimental results demonstrate that the PNA–DOX@PDA–FA nanoparticles can be phagocytized by 4T1 tumor cells and release drugs in tumor cell acidic environments, and confirm that the combined chemo and photothermal therapeutic efficacy of PNA–DOX@PDA–FA nanoparticles is higher than the photothermal therapeutic efficacy or the chemotherapeutic efficacy alone. The proposed multifunctional responsive nanoparticles in this study provide a novel class of drug nanocarriers as a promising tool for synergetic chemo–photothermal therapy of tumors.

A smart-hydrogel-based ultrasensitive grating system with ultra-low detection limit for highly-selective and rapid detection of trace heavy metal ions is developed.

A simple grating system based on poly­(N-isopropylacrylamide-co-acrylamide) (poly­(NIPAM-co-AAm)) hydrogel for sensitive and rapid detection of ethanol concentration is developed. The hydrogel gratings enable ethanol-induced shrinking, thus changing their refractive index and height. The changes in the optical property and structure of hydrogel gratings allow efficient conversion and amplification of signals of ethanol concentration into changes in the diffraction efficiency for facile detection of ethanol concentration via a simple optical detection system. By adjusting the molar ratios of NIPAM and AAm in the hydrogel gratings, significant diffraction efficiency changes in response to ethanol concentrations in the range of 0–30 vol % at different temperatures can be achieved for sensitive ethanol detection. Moreover, the hydrogel gratings with nanometer-sized height and uniform surface relief structures allow rapid response time (less than 2 min) and good repeatability for ethanol detection.

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