Light Controllable Surface Coating for Effective Photothermal Killing of Bacteria

Although the electronic properties of conducting films have been widely explored in optoelectronic fields, the optical absorption abilities of surface-coated films for photothermal conversion have been relatively less explored in the production of antibacterial coatings. Here, we present catechol-conjugated poly­(vinylpyrrolidone) sulfobetaine (PVPS) and polyaniline (PANI) tightly linked by ionic interaction (PVPS:PANI) as a novel photothermal antibacterial agent for surface coating, which can absorb broadband near-infrared (NIR) light. Taking advantage of the NIR light absorption, this coating film can release eminent photothermal heat for the rapid killing of surface bacteria. The NIR light triggers a sharp rise in photothermal heat, providing the rapid and effective killing of 99.9% of the Gram-positive and -negative bacteria tested within 3 min of NIR light exposure when used at the concentration of 1 mg/mL. Although considerable progress has been made in the design of antibacterial coatings, the user control of NIR-irradiated rapid photothermal destruction of surface bacteria holds increasing attention beyond the traditional boundaries of typical antibacterial surfaces

Determination of Cancer Cell-Based pH-Sensitive Fluorescent Carbon Nanoparticles of Cross-Linked Polydopamine by Fluorescence Sensing of Alkaline Phosphatase Activity on Coated Surfaces and Aqueous Solution

The tumor-specific sensitive fluorescence sensing of cellular alkaline phosphatase (ALP) activity on the basis of host–guest specific and pH sensitivity was conducted on coated surfaces and aqueous states. Cross-linked fluorescent nanoparticles (C-FNP) consisting of β-cyclodextrin (β-CD)/boronic acid (BA) and fluorescent hyaluronic acid [FNP­(HA)] were conjugated to fluorescent polydopamine [FNP­(pDA)]. To determine the quenching effect of this system, hydrolysis of 4-nitrophenyl phosphate (NPP) to 4-nitrophenol (NP) was performed in the cavity of β-CD in the presence of ALP activated photoinduced electron transfer (PET) between NP and C-FNP. At an ALP level of 30–1000 U/L, NP caused off-emission of C-FNP because of their specific host–guest recognition. Fluorescence can be recovered under pH shock due to cleavage of the diol bond between β-CD and BA, resulting in release of NP from the fluorescent system. Sensitivity of the assays was assessed by confocal imaging not only in aqueous states, but also for the first time on coated surfaces in MDAMB-231 and MDCK cells. This novel system demonstrated high sensitivity to ALP through generation of good electron donor/acceptor pair during the PET process. Therefore, this fluorescence sensor system can be used to enhance ALP monitoring and cancer diagnosis on both coated surfaces and in aqueous states in clinical settings

Visible-Light-Driven Photocatalysts of Perfluorinated Silica-Based Fluorescent Carbon Dot/TiO₂ for Tunable Hydrophilic–Hydrophobic Surfaces

In this study, a new hydrophilic–hydrophobic transition surface was designed via visible-light-induced photocatalytic perfluorinated silica-based fluorescent carbon nanoparticles (FNPs)/TiO₂. Perfluorinated silica–polydopamine hybrid FNPs (<i>f</i>-FNPs) were easily fabricated by carbonization in an emulsion system consisting of tetraethyl orthosilicate and dopamine, followed by the deposition of TiO₂ on <i>f</i>-FNPs, which demonstrated the reversal from hydrophobic to hydrophilic nature during successful photocatalysis. The synergistic effect of silica–carbon and the deposited TiO₂ NPs led to the decomposition of methylene blue under UV and visible light irradiation, demonstrating that FNPs/TiO₂ sustains photocatalytic activity. The profound contact angle with the catalytic kinetics curve and precise morphology and extension of cells detach antifouling exceptionally unrestricted the synergistic effect of silica–carbon on TiO₂ NPs on a coated paper substrate. Given the interest in the manipulation of hydrophobicity and hydrophilicity, this study can serve as a guideline for the fabrication of photocatalytic surfaces where water spreads completely

Highly Efficient Visible Blue-Emitting Black Phosphorus Quantum Dot: Mussel-Inspired Surface Functionalization for Bioapplications

The preparation of blue-emitting black phosphorus quantum dots (BPQDs) is based on the liquid-phase exfoliation of bulk BP. We report the synthesis of soluble BPQDs showing a strong visible blue-light emission. Highly fluorescent (photoluminescence quantum yield of ≈5% with the maximum emission (λ_max) at ≈437 nm) and dispersible BPQDs in various organic solvents are first prepared by simple ultrasonication of BP crystals in chloroform in the ambient atmosphere. Furthermore, simple mussel-inspired surface functionalization of BPQDs with catechol-grafted poly­(ethylene glycol) in basic buffer afforded water-soluble blue-emitting BPQDs showing long-term fluorescence stability, very low cytotoxicity, and excellent fluorescence live cell imaging capability