Ming-Jay Deng

Mercury (Hg) is a toxic element which impacts on biological systems and ecosystems. Because the toxicity of Hg species is highly dependent on their concentration levels and chemical forms, the sensitive identification of the chemical forms of Hg—i.e., Hg speciation—is of major significance in providing meaningful information about the sources of Hg exposure. In this study, a microfluidic-based device made of high-clarity poly(methyl methacrylate) (PMMA) was fabricated. Then, titanium dioxide nanoparticles (nano-TiO₂s) were attached to the treated channel’s interior with the aid of poly(diallyldimethylammonium chloride) (PDADMAC). After coupling the nano-TiO₂-coated microfluidic-based photocatalyst-assisted reduction device (the nano-TiO₂-coated microfluidic-based PCARD) with high-performance liquid chromatography (HPLC) and inductively coupled plasma mass spectrometry (ICP-MS), a selective and sensitive, hyphenated system for Hg speciation was established. Validation procedures demonstrated that the method could be satisfactorily applied to the determination of mercury ions (Hg²⁺) and methylmercury ions (CH₃Hg⁺) in both human urine and water samples. Remarkably, the zeta potential measured clearly indicated that the PDADMAC-capped nano-TiO₂s with a predominance of positive charges indeed provided a steady force for firm attachment to the negatively charged device channel. The cause of the durability of the nano-TiO₂-coated microfluidic-based PCARD was clarified thus.

Mercury (Hg) is a toxic element impacting on biological systems and ecosystems. Because the toxicity of Hg species is highly dependent on concentration levels and chemical forms, sensitive identification of chemical forms for Hg, i.e., Hg speciation, is of major significance in providing meaningful information about the source of Hg exposure. In this study, a microfluidic-based device made of high clarity poly(methyl methacrylate) (PMMA) was fabricated. Then titanium dioxide nanoparticles (nano-TiO2) were attached to the treated channel interior with the aid of poly(diallyldimethylammonium chloride) (PDADMAC). After coupling the nano-TiO2-coated microfluidic-based photocatalyst-assisted reduction device (the nano-TiO2-coated microfluid-ic-based PCARD) with high-performance liquid chromatography (HPLC) and inductively coupled plasma-mass spectrometry (ICP-MS), a selective and sensitive hyphenated system for Hg specia-tion was established. Validation procedures demonstrated that the method could be satisfactorily applied to the determination of mercuric ion (Hg2+) and methylmercury ion (CH3Hg+) in both human urine and water samples. Remarkably, the zeta potential measured clearly indicated the PDADMAC-capped nano-TiO2 with predominance of positive charges indeed provided steady force for firm attachment to the negatively charged device channel. The cause for the durability of the nano-TiO2-coated microfluidic-based PCARD was clarified thus.

Flexible electrochemical supercapacitors (FESCs) are emerging as innovative energy storage systems, characterized by their stable performance, long cycle life, and portability/foldability. Crucial components of FESCs, such as electrodes and efficient electrolytes, have become the focus of extensive research. Herein, we examine deep eutectic solvent (DES)–based polymer gel systems for their cost-effective accessibility, simple synthesis, excellent biocompatibility, and exceptional thermal and electrochemical stability. We used a mixture a DES, LiClO₄–2-Oxazolidinone as the electroactive species, and a polymer, either polyvinyl alcohol (PVA) or polyacrylamide (PAAM) as a redox additive/plasticizer. This combination facilitates a unique ion-transport process, enhancing the overall electrochemical performance of the polymer gel electrolyte. We manufactured and used LiClO₄–2-Oxazolidinone (LO), polyvinyl alcohol–LiClO₄–2-Oxazolidinone (PVA–LO), and polyacrylamide–LiClO₄–2-Oxazolidinone (PAAM–LO) electrolytes to synthesize an MnO₂ symmetric FESC. To evaluate their performance, we analyzed the MnO₂ symmetric FESC using various electrolytes with cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The FESC featuring the PVA–LO electrolyte demonstrated superior electrochemical and mechanical performances. This solid-state MnO₂ symmetric FESC exhibited a specific capacitance of 121.6 F/g within a potential window of 2.4 V. Due to the excellent ionic conductivity and the wide electrochemical operating voltage range of the PVA–LO electrolyte, a high energy density of 97.3 Wh/kg at 1200 W/kg, and a long-lasting energy storage system (89.7% capacitance retention after 5000 cycles of GCD at 2 A/g) are feasibly achieved. For practical applications, we employed the MnO₂ symmetric FESCs with the PVA–LO electrolyte to power a digital watch and a light-emitting diode, further demonstrating their real-world utility.

Herein, the nanostructured polypyrrole-coated MnO₂ nanofibers growth on carbon cloth (PPy-MnO₂-CC) to serve as the electrodes used in conjunction with a quasi-ionic liquid-based polymer gel electrolyte (urea-LiClO₄-PVA) for solid-state symmetric supercapacitors (SSCs). The resultant PPy-MnO₂-CC solid-state SSCs exhibited a high specific capacitance of 270 F/g at 1.0 A/g in a stable and wide potential window of 2.1 V with a high energy/power density (165.3 Wh/kg at 1.0 kW/kg and 21.0 kW/kg at 86.4 Wh/kg) along with great cycling stability (capacitance retention of 92.1% retention after 3000 cycles) and rate capability (141 F/g at 20 A/g), exceeding most of the previously reported SSCs. The outstanding performance of the studied 2.1 V PPy-MnO₂-CC flexible SSCs could be attributed to the nanostructured PPy-coated MnO₂ composite electrode and the urea-LiClO₄-PVA polymer gel electrolyte design. In addition, the PPy-MnO₂-CC solid-state SSCs could effectively retain their electrochemical performance at various bending angles, demonstrating their huge potential as power sources for flexible and lightweight electronic devices. This work offers an easy way to design and achieve light weight and high-performance SSCs with enhanced energy/power density.

The specific energy of an aqueous carbon supercapacitor is generally small, resulting mainly from a narrow potential window of aqueous electrolytes. Here, we introduced agarose, an ecologically compatible polymer, as a novel binder to fabricate an activated carbon supercapacitor, enabling a wider potential window attributed to a high overpotential of the hydrogen-evolution reaction (HER) of agarose-bound activated carbons in sulfuric acid. Assembled symmetric aqueous cells can be galvanostatically cycled up to 1.8 V, attaining an enhanced energy density of 13.5 W h/kg (9.5 µW h/cm²) at 450 W/kg (315 µW/cm²). Furthermore, a great cycling behavior was obtained, with a 94.2% retention of capacitance after 10,000 cycles at 2 A/g. This work might guide the design of an alternative material for high-energy aqueous supercapacitors.

Apigenin (Apig) is used as a model drug due to its many beneficial bio-activities and therapeutic potentials. Nevertheless, its poor water solubility and low storage stability have limited its application feasibility on the pharmaceutical field. To address this issue, this study developed nanoemulsions (NEs) using an anti-oxidative polymeric amphiphile, d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), hydrogenated soy lecithin (HL), black soldier fly larvae (BSFL) oil, and avocado (AV) oil through pre-homogenization and ultrasonication method. Addition of TPGS (weight ratios 100 and 50% as compared to HL) into NEs effectively reduced particle size and phase transition region area of NEs with pure HL. Incorporation of Apig into NEs made particle size increase and provided a disorder effect on intraparticle molecular packing. Nevertheless, the encapsulation efficiency of NEs for Apig approached to about 99%. The chemical stability of Apig was significantly improved and its antioxidant ability was elevated by incorporation with BSFL oil and AV oil NEs, especially for NEs with single TPGS. NEs with single TPGS also exhibited the best Apig skin deposition. For future application of topical Apig delivery, NEs-gel was formed by the addition of hyaluronic acid (HA) into NEs. Their rheological characteristics were dominated by the surfactant ratios of HL to TPGS.