RESUMEN

To prevent bacterial contamination on solid surfaces, a simple yet efficient antibacterial coating was developed in a substrate-independent manner by using the catechol-conjugated carboxymethyl chitosan (CMC-DOPA). The CMC-DOPA was firstly synthesized via an aza-Michael reaction with methyl acrylate and the subsequent acyl substitution with dopamine. The coating strategy consists of spin-coating-assisted deposition of CMC-DOPA on polydopamine-coated substrates and coordination-driven crosslinks between catechol groups and Fe3+ ions in sequence, producing the multilayered CMC-DOPA films. The film thickness was controllable depending on the concentration of CMC-DOPA. Compared to bare controls, the CMC-DOPA-coated substrates reduced the bacterial adhesion by up to 99.8 % and 96.2 % for E. coli and S. aureus, respectively. It is demonstrated that the CMC-DOPA coating can be a robust antibacterial coating across various pH environments, inhibiting bacterial adhesion by 78.7 %, 95.1 %, and 93.2 %, respectively, compared to the control, even after 7 days of acidic, physiological, and alkaline pH treatment. The current coating approach could be applied to various substrates including silicon dioxide, titanium dioxide, and polyurethane. Given its simple and versatile coating capability, we think that the coordination-driven CMC-DOPA coating could be useful for various medical devices and implants.

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RESUMEN

The growing evolution of bacterial resistance to antibiotics represents a global issue that not only impacts healthcare systems but also political and economic processes. This necessitates the development of novel antibacterial agents. Antimicrobial peptides have shown promise in this regard. Thus, in this study, a new functional polymer was synthesized by joining a short oligopeptide sequence (Phe-Lys-Phe-Leu, FKFL) to the surface of a second-generation polyamidoamine (G2 PAMAM) dendrimer as an antibacterial component. This method of synthesis proved simple and resulted in a high conjugation yield of the product FKFL-G2. To determine its antibacterial potential, FKFL-G2 was subsequently analyzed via mass spectrometry, a cytotoxicity assay, bacterial growth assay, colony-forming unit assay, membrane permeabilization assay, transmission electron microscopy, and biofilm formation assay. FKFL-G2 was found to exhibit low toxicity to noncancerous NIH3T3 cells. Additionally, FKFL-G2 had an antibacterial effect on Escherichia coli and Staphylococcus aureus strains by interacting with and disrupting the bacterial cell membrane. Based on these findings, FKFL-G2 shows promise as a potential antibacterial agent.

RESUMEN

Targeted drugs have been used to treat mitochondrial dysfunction-related diseases, including metabolic disorders and cancer; however, targeting and penetrating intracellular organelles remains a challenge. Dominant targeting approaches for therapeutic delivery are detailed in many nanoemulsion studies and show the tremendous potential of targeted delivery to inhibit cancer cell growth. Dequalinium (DQA) and α-tocopherol succinate (α-TOS) are good agents for targeting mitochondria. In this study, we aimed to develop a mitochondria-targeting emulsion, using DQA and α-TOS (DTOS), for cancer treatment. DTOS emulsions of 150-170 nm in diameter were formulated using homogenization. DQA and α-TOS were used as bifunctional agents (surfactants) to stabilize the nanoemulsion and anticancer drugs. Various molar ratios of DQA and α-TOS were tested to determine the optimal condition, and DTOS 5-5 was selected for further study. The DTOS emulsion showed improved stability, as evidenced by its ability to remain stable for three years at room temperature. This stability, combined with its effective targeting of mitochondria, led to inhibition of 71.5% of HeLa cells after 24 h. The DTOS emulsion effectively inhibited spheroid growth in the 3D model, as well as prevented the growth of HeLa cells grafted onto zebrafish larvae. These results highlight the DTOS emulsion's promising potential for mitochondria-targeting and cancer treatment.

RESUMEN

Development of efficient surface passivation methods for semiconductor devices is crucial to counter the degradation in their electrical performance owing to scattering or trapping of carriers in the channels induced by molecular adsorption from the ambient environment. However, conventional dielectric deposition involves the formation of additional interfacial defects associated with broken covalent bonds, resulting in accidental electrostatic doping or enhanced hysteretic behavior. In this study, centimeter-scaled van der Waals passivation of transition metal dichalcogenides (TMDCs) is demonstrated by stacking hydrocarbon (HC) dielectrics onto MoSe2 field-effect transistors (FETs), thereby enhancing the electric performance and stability of the device, accompanied with the suppression of chemical disorder at the HC/TMDCs interface. The stacking of HC onto MoSe2 FETs enhances the carrier mobility of MoSe2 FET by over 50% at the n-branch, and a significant decrease in hysteresis, owing to the screening of molecular adsorption. The electron mobility and hysteresis of the HC/MoSe2 FETs are verified to be nearly intact compared to those of the fabricated HC/MoSe2 FETs after exposure to ambient environment for 3 months. Consequently, the proposed design can act as a model for developing advanced nanoelectronics applications based on layered materials for mass production.