Copper nanoclusters (DPA@CuNCs) with red fluorescence were successfully synthesized by a one-step method based on D-penicillamine (DPA), which acted not only as a reducing agent but also as a stabilizer. The products were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, particle-size analysis, ultraviolet-visible spectrophotometry, and fluorescence spectrometry. When the excitation wavelength was 280 nm, DPA@CuNCs emitted bright red fluorescence at 640 nm with a fluorescence quantum yield of 5.8 %. Due to the inner filter effect, oxytetracycline (OTC) effectively quenched the fluorescence of DPA@CuNCs, and then DPA@CuNCs were applied to the trace detection of OTC. The method showed a good linear range for OTC from 5 to 60 & mu;mol/L, with a detection limit of 0.026 & mu;mol/L and a correlation coefficient R2 of 0.9983. Moreover, a paper-based sensor for the visual detection of OTC has been developed, which can conveniently and rapidly distinguish the concentration ranges of OTC through the color changes of the test papers.

The development of fluorescent probes capable of detecting abnormal changes in cellular mitochondrial viscosity is of great significance, as these changes have been connected to many diseases. In this study, the conventional tetraphenylethylene (TPE) molecule was modified to fabricate a novel near-infrared fluorescent, TTPB, which was then used to measure the mitochondrial viscosity. Due to the introduction of TPE and pyridine groups, TTPB had an AIE effect and mitochondrial targeting function. Meanwhile, TTPB was extremely sensitive to variations in viscosity for the twisted intramolecular charge transfer (TICT) phenomenon. The logarithm of fluorescence intensity (logI620) of the probe demonstrated an excellent linear connection with the logarithm of viscosity (logη) in the viscosity range of 1.2 ∼ 956.0 cP, indicating the probe could quantitatively detect viscosity. Moreover, TTPB was able to visually track autophagy in addition to detecting the mitochondrial viscosity in the inflammatory cell model. These results showed that the probe was anticipated to be employed for the early diagnosis of related diseases.

Abnormal viscosity and excessive superoxide anion (O2•-) levels in living cells often cause a series of biological dysfunction and oxidative damage. However, a great challenge remains in quickly and conveniently detecting the viscosity and O2•- levels in living cells. Herein, we fabricated a versatile aggregation-induced emission (AIE) probe with mitochondria targeting, DTPB, for dual-imaging of viscosity and O2•- level in living cells with two different channels. The obtained DTPB contained a diphenyl phosphinic acid unit responsive to O2•-, a unit with twisted intramolecular charge trans (TICT) function responsive to viscosity, and a pyridine cation unit with mitochondria targeting. The results showed that DTPB exhibited a remarkable response to viscosity with a near-infrared emission peak at 671 nm and was highly sensitive to O2•- levels with an emission peak at 587 nm. The dual-channel probe has great application prospects in the visual diagnosis of cancer and related diseases.

Amphiphilic AIE nanoparticles (CD-TPE) were obtained by linking γ-cyclodextrin (γ-CD) and 1, 2-diphenyl-1, 2-(p-hydroxyphenyl)-ethylene (OH-TPE-OH) by an esterification reaction using hexamethylene diisocyanate (HMDI) in a one-step process. The CD-TPE was characterized by FTIR, 13C NMR, DSC, XRD, particle size analysis, TEM, and FL. The obtained CD-TPE had good water dispersibility and could self-assemble into AIE nanoparticles. The large cavity of CD-TPE provided convenient conditions for the loading of doxorubicin (DOX) and slow-release DOX with the loading and release rates of 67.4 % and 71.3 % (pH = 5.4), respectively. The DOX release kinetic model was suitable for the Bhaskar model. Cytotoxicity analysis and cell imaging of CD-TPE were performed, showing that CD-TPE has good biocompatibility and excellent cell imaging performance. Moreover, both in vitro and in vivo antitumor experiments showed that CD-TPE has promising applications in drug delivery.

Green and low-cost photoluminescent graphene quantum dots (GQDs) were prepared by a one-step hydrothermal method with konjac glucomannan (KGM), a natural polysaccharide, as the precursors. Then, the folic acid (FA)-functionalized GQDs (FA-GQDs) was formed by the amidation of GQDs with FA, and the drug carrier named as FA-GQDs-DOX was obtained by loading doxorubicin (DOX) on FA-GQDs. Due to the inherent fluorescence properties of GQDs and DOX in FA-GQDs-DOX, the resultant samples could be used to selectively label cancer cells without external dyes, and the cellular uptake and the drug-releasing behavior could be visualized. The coupling of FA with GQDs and the loading of DOX on FA-GQDs were confirmed by various means. In addition, the cell imaging showed that the FA-GQDs could be used as a fluorescent probe to recognize folate receptor (FR)-positive cancer cells and that the FA-GQDs-DOX could selectively deliver DOX to FR-positive cancer cells. As a result, the FA-GQDs-DOX could be applied in early diagnosis and targeted therapy of cancer.

Recently, the design of aggregation-induced emission (AIE) materials with good water-solubility and biocompatibility has attracted much attention. In this work, amphiphilic AIE-active nanoparticles (KGM-TPE) were synthesized by a facile Schiff base condensation of oxidized konjac glucomannan with aminotetraphenylethylene. The final KGM-TPE had good water dispersibility and could self-assemble into nanoparticles with average diameters ranging from 100 to 200 nm. A cytotoxicity test showed that the cell survival was approximately 90% even when the concentration of KGM-TPE reached 150 mu g/mL, indicating that KGM-TPE possessed good biocompatibility. In addition, the excellent cell imaging and good anti-counterfeiting function results of KGM-TPE indicated that this material has great potential in the fields of biomedicine and anticounterfeiting.

A novel supramolecular polysaccharide composite [KGM + DB18C6] was prepared from konjac glucomannan (KGM) and dibenzo-18-crown-6 (DB18C6) using ceric ammonium nitrate as initiator. The products were characterized by FTIR, TG, DSC, UV-Vis, XRD, solid-state C-13 NMR, and SEM. Due to the introduction of crown ether, [KGM+ DB18C6] showed good adsorption performance for Cu2+ in aqueous, and the maximum adsorption capacity was 194 mg/g under the optimal adsorption condition. The adsorption kinetics of [KGM + DB18C6] on Cu2+ could be described by the pseudo-second-order kinetic model. The adsorption isotherms of [KGM + DB18C6] on Cu2+ followed the dual-site Langmuir-Freundlich model. In addition, high recoveries of Cu2+ (from 82.65 to 88.47%), and low relative standard deviation (below 5.00%) were obtained by applying the product in real samples, indicating that [KGM + DB18C6] was a good absorbent for removing Cu2+ in wastewater. (c) 2021 Elsevier B.V. All rights reserved.

A positively charged konjac glucomannan-graft-poly-(2-methacryloyloxyethyl) trimethyl ammonium chloride (KGM-g-PDMC) was prepared by using ceric ammonium nitrate as the initiator in aqueous solution. Negatively charged copper nanoclusters (CuNCs) were prepared by a one-step reduction method using glutathione as the reductant. Then, the two precursors mentioned above were combined through electrostatic attraction to form a conjugate (KGM-g-PDMC/CuNCs) exhibiting aggregation-induced emission (AIE). The resultant products were characterized by Fourier transform infrared spectroscopy, zeta potential and particle size analysis, X-ray photoelectron spectrometry, transmission electron microscopy, and fluorescence spectrophotometry. The results showed that KGM-g-PDMC enhanced the AIE effect of CuNCs, with an approximate 4-fold increase in fluorescence intensity. A cytotoxicity analysis showed that the products possess good biocompatibility. Moreover, cell imaging indicated that the products have potential for application in the field of biomedicine.