Mechanochemical synthesis of fluorescent carbon dots from cellulose powders.

A novel mechanochemical method was firstly developed to synthesize carbon nanodots (CNDs) or carbon nano-onions (CNOs) through high-pressure homogenization of cellulose powders as naturally abundant resource depending on the treatment times. While CNDs (less than 5 nm in size) showed spherical and amorphous morphology, CNOs (10-50 nm in size) presented polyhedral shape, and onion-like outer lattice structure, graphene-like interlattice spacing of 0.36 nm. CNOs showed blue emissions, moderate dispersibility in aqueous media, and high cell viability, which enables efficient fluorescence imaging of cellular media.

Preparation of carbon dot-based ratiometric fluorescent probes for cellular imaging from Curcuma longa.

This work derived biocompatible and stable probes based on fluorescent nanoparticles (FNPs) from a natural source, Curcuma longa. The multi-color fluorescence emissions from carbonized Curcuma longa (C-FNPs) obtained through defined dehydration conditions are soluble in water and have a small particle size (~17 nm). The surface passivation with polyethylene glycol (PEG) capped with amine groups in FNPs (P-FNPs) generated a probe with a higher quantum yield and longer fluorescence lifetime than obtained with C-FNPs. The X-ray photoelectron spectroscopy and X-ray diffraction spectra confirmed the associated chemical moieties of C-FNPs and P-FNPs. Furthermore, the prepared material showed non-toxic effects with almost 100% cell viability, even at high concentrations. In conclusion, fluorescence sensors from natural sources may be useful for numerous biomedical research applications.

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 ß-cyclodextrin (ß-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 ß-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 ß-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.

pH-Responsible fluorescent carbon nanoparticles for tumor selective theranostics via pH-turn on/off fluorescence and photothermal effect in vivo and in vitro.

We developed nanoparticles comprising a photothermal dye (IR825)-loaded carbonized zwitterionic polymer [FNP-I] as "switch-on" pH-responsive fluorescence probes to sense intracellular cancer cells and for near-infrared (NIR) controllable photothermal therapy (PTT) in vivo and in vitro. The fluorescent "off" of FNP-I was activated after reaching the cancer cell environment, where the zwitterionic compartment of FNP lost its hydrophobicity to induce PTT-mediated heat release of IR825 under NIR irradiation in the tumor. Approximately 100% of the IR825 was released from the FNP core to generate high thermal conversion to completely kill the cancer cells. Furthermore, after intravenous treatment of FNP-I into MDAMB-231-cell bearing mice, pH-responsive photothermal therapy was observed, achieving marked ablation of tumor cells with release of IR825 under tumor environment conditions. In addition, fluorescent signals were clearly found at the tumor site after 3 h, decreasing at the 6 h time point. The in vitro and in vivo detection system demonstrated good cellular uptake and biocompatibility as a potential imaging-guided photothermal therapy nanotool for cancer treatment. Interestingly, the synergism of the biosensor and PTT in single FNP-I platform led to more effective cancer cell killing than either monotherapy, providing a new approach for cancer treatment.

Preparation of dual-responsive hybrid fluorescent nano probe based on graphene oxide and boronic acid/BODIPY-conjugated polymer for cell imaging.

Here, we report a pH- and thermo-responsive fluorescent nanomaterial of functionalized reduced graphene oxide (rGO) with cross-linked polymer produced via catechol-boronate diol binding mechanism. When conjugated with the hydrophobic dye boron dipyrromethane (BODIPY), this material can act as a dual-responsive nanoplatform for cells imaging. 2-Chloro-3',4'-dihydroxyacetophenone (CCDP)-quaternized-poly(dimethylaminoethyl methacrylate-co-N-isopropylacrylamide) [C-PDN] was cross-linked with BODIPY and 4-chlorophenyl boronic acid (BA)-quaternized-poly(ethylene glycol)-g-poly(dimethylaminoethyl methacrylate-co-N-isopropylacrylamide) [BB-PPDN]. The GO was then reduced by the catechol group in the cross-linked polymer to synthesize rGO nanoparticles, which able to stabilize the quenching mechanism. This nanoplatform exhibits intense fluorescence at acidic pH and low fluorescence at physiological pH. Confocal laser scanning microscopy (CLSM) images shows bright fluorescence at lysosomal pH and total quench at physiological pH. Therefore, we have successfully developed a promising sensitive bio-imaging probe for identifying cancer cells.

Performance of NIR-Mediated Antibacterial Continuous Flow Microreactors Prepared by Mussel-Inspired Immobilization of Cs0.33WO3 Photothermal Agents.

An antibacterial continuous flow microreactor was successfully prepared by sequential mussel-inspired surface engineering of microchannels by using catechol-grafted poly(N-vinylpyrrolidone) and immobilization of near-infrared active Cs0.33WO3 nanoparticles inside the polydimethylsiloxane(PDMS)-based microreactors. Excellent phothothermal antibacterial acitivity over 99.9% was accomplished toward Gram-positive and -negative bacteria upon near-infrared irradiation during continuous operation up to 30 days. This was achieved without releasing Cs0.33WO3 nanoparticles from the surface of the microchannels, confirming the robust immobilization of photothermal agents through the mussel-inspired chemistry. The cleaning of used microreactors was easily attainable by simple acid treatment to release immobilized photothermal agents from the surface of the microchannels, enabling efficient recycling of used microreactors.

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 (λmax) 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.

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 (f-FNPs) were easily fabricated by carbonization in an emulsion system consisting of tetraethyl orthosilicate and dopamine, followed by the deposition of TiO2 on f-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.

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.