On-Chip Micro-Supercapacitor with High Areal Energy Density Based on Dielectrophoretic Assembly of Nanoporous Metal Microwire Electrodes.

Advances in the Internet of Things (IoT) technology have driven the demand for miniaturized electronic devices, prompting research on small-scale energy-storage systems. Micro-supercapacitors (MSCs) stand out in this regard because of their compact size, high power density, high charge-discharge rate, and extended cycle life. However, their limited energy density impedes commercialization. To resolve this issue, a simple and innovative approach is reported herein for fabricating highly efficient on-chip MSCs integrated with nanoporous metal microwires formed by dielectrophoresis (DEP)-driven gold nanoparticle (AuNP) assembly. Placing a water-based AuNP suspension onto interdigitated electrodes and applying an alternating voltage induces in-plane porous microwire formation in the electrode gap. The DEP-induced AuNP assembly and the gold microwire (AuMW) growth rate can be adjusted by controlling the applied alternating voltage and frequency. The microwire-integrated MSC (AuMW-MSC) electrically outperforms its unmodified counterpart and exhibits a 30% larger electrode area, along with 72% and 78% higher specific and areal capacitances, respectively, than a microwire-free MSC. Additionally, AuMW-MSC achieves maximum energy and power densities of 3.33 µWh cm-2 and 2629 µW cm-2 , respectively, with a gel electrolyte. These findings can help upgrade MSCs to function as potent energy-storage devices for small electronics.

Foldable RF Energy Harvesting System Based on Vertically Layered Metal Electrodes within a Single Sheet of Paper.

Radio frequency energy harvesting (RFEH) systems have emerged as a critical component for powering devices and replacing traditional batteries, with paper being one of the most promising substrates for use in flexible RFEH systems. However, previous paper-based electronics with optimized porosity, surface roughness, and hygroscopicity still face limitations in terms of the development of integrated foldable RFEH systems within a single sheet of paper. In the present study, a novel wax-printing control and water-based solution process are used to realize an integrated foldable RFEH system within a single sheet of paper. The proposed paper-based device includes vertically layered foldable metal electrodes, a via-hole, and stable conductive patterns with a sheet resistance of less than 1 Ω sq-1 . The proposed RFEH system exhibits an RF/DC conversion efficiency of 60% and an operating voltage of 2.1 V in 100 s at a distance of 50 mm and a transmitted power of 50 mW. The integrated RFEH system also demonstrates stable foldability, with RFEH performance maintained up to a folding angle of 150°. The single-sheet paper-based RFEH system thus has the potential for use in practical applications associated with the remote powering of wearable and Internet-of-Things devices and in paper electronics.

Cancer cell-specific photoactivity of pheophorbide a-glycol chitosan nanoparticles for photodynamic therapy in tumor-bearing mice.

We designed a cancer-cell specific photosensitizer nano-carrier by synthesizing pheophorbide a (PheoA) conjugated glycol chitosan (GC) with reducible disulfide bonds (PheoA-ss-GC). The amphiphilic PheoA-ss-GC conjugates self-assembled in aqueous condition to form core-shell structured nanoparticles (PheoA-ss-CNPs) with good colloidal stability and switchable photoactivity. The photoactivity of PheoA-ss-CNPs in an aqueous environment was greatly suppressed by the self-quenching effect, which enabled the PheoA-ss-CNPs to remain photo-inactive and in a quenched state. However, after the cancer cell-specific uptake, the nanoparticular structure instantaneously dissociated by reductive cleavage of the disulfide linkers, followed by an efficient dequenching process. Compared to non-reducible PheoA-conjugated GC-NPs with stable amide linkages (PheoA-CNPs), PheoA-ss-CNPs rapidly restored their photoactivity in response to intracellular reductive conditions, thus presenting higher cytotoxicity with light treatment. In addition, the PheoA-ss-CNPs presented prolonged blood circulation in vivo compared to free PheoA, demonstrating enhanced tumor specific targeting behavior through the enhanced permeation and retention (EPR) effect. The enhanced tumor accumulation of PheoA-ss-CNPs enabled tumor therapeutic efficacy that was more efficient than free PheoA in tumor-bearing mice. Based on the enhanced intracellular release for cytosolic high dose and switchable photoactivity mechanism for reduced side effects, these results suggest that PheoA-ss-CNPs have good potential for photodynamic therapy (PDT) in cancer treatment.

Ternary biomolecular nanoparticles for targeting of cancer cells and anti-angiogenesis.

To develop a targeted drug delivery system for cancer therapy and anti-angiogenesis, amphiphilic heparin bioconjugates were synthesized by chemical conjugation of hydrophobic retinoic acid and a targeting ligand, folic acid, to the heparin backbone (HFR). The chemical structure of the HFR conjugates was confirmed by proton nuclear magnetic resonance ((1)H NMR). Various HFR conjugates with different retinoic acid coupling ratios were obtained by modulating the retinoic acid feed molar ratio. The anticoagulant activity of the HFR conjugates decreased to 30% of heparin levels as measured by anti-FXa chromogenic assay. The bioconjugates retained the anti-angiogenic effect, showing a significant decrease in endothelial tubular formation using a Matrigel model. In aqueous solutions, the bioconjugates readily self-assembled to form nanoparticles via the hydrophobic interaction among retinoic acid. The HFR nanoparticles were spherical and ranged from 150 to 300 nm, depending on the degree of retinoic acid coupling. The presence of folic acid efficiently enhanced the cellular uptake of the HFR nanoparticles in folate receptor-positive cells. Furthermore, the internalized HFR nanoparticles demonstrated greater cytotoxicity against folate receptor-positive cells compared to free retinoic acid. These results indicate that specific delivery of retinoic acid with ternary biomolecular nanoparticles targeting folate receptor-positive tumors is a promising strategy to enhance chemotherapy efficacy with minimal side effects.