Highly stable and biocompatible nanocontrast agent encapsulating a novel organic fluorescent dye for enhanced cellular imaging

High biocompatible FITC-conjugated silica nanoparticles for cell labeling in both in vitro and in vivo models

Fluorescence nanosilica-based cell tracker has been explored and applied in cell biological research. However, the aggregation of these nanoparticles at physiological pH is still the main limitation. In this research, we introduced a novel fluorescence nano-based cell tracker suitable for application in live cells. The silica-coated fluorescein isothiocyanate isomer (FITC-SiO2) nanoparticles (NPs) were modified with carboxymethylsilanetriol disodium salt (FITC-SiO2-COOH), integrating the dianion form of FITC molecules. This nanosystem exhibited superior dispersion in aqueous solutions and effectively mitigated dye leakage. These labeled NPs displayed notable biocompatibility and minimal cytotoxicity in both in vitro and in vivo conditions. Significantly, the NPs did not have negative implications on cell migration or angiogenesis. They successfully penetrated primary fibroblasts, human umbilical vein endothelial cells and HeLa cells in both 2D and 3D cultures, with the fluorescence signal enduring for over 72 h. Furthermore, the NP signals were consistently observed in the developing gastrointestinal tract of live medaka fish larvae for extended periods during phases of subdued digestive activity, without manifesting any apparent acute toxicity. These results underscore the promising utility of FITC-SiO2-COOH NPs as advanced live cell trackers in biological research.

Recent Progress in Research on [2.2]Paracyclophane-Based Dyes

In recent years, the [2.2]paracyclophane (PCP) ring has attracted extensive attention due to its features of providing not only chirality and electron-donating ability but also steric hindrance, which reduces intermolecular π-π stacking interactions and thereby improves the fluorescence properties of dyes. To date, some circularly polarized luminescence (CPL)-active small organic molecules based on the PCP skeleton have been reviewed; however, the application of the PCP ring in improving the photophysical properties of fluorescent dyes is still limited, and new molecular design strategies are still required. This review summarizes and promotes the application of PCP in fluorescent dye design, fluorescence detection, and CPL modulation. We expect that this review will provide readers with a comprehensive understanding of the PCP skeleton and lead to further improvement in fluorescent dye design.

Photodynamic nano hydroxyapatite with biofilm penetration capability for dental plaque eradication and prevention of demineralization

Dental caries represents one of the most prevalent diseases worldwide, characteristic of the growth of dental plaque and demineralization of tooth enamel. Current medications for eradication of dental plaques and prevention of demineralization suffer from several limitations to overcome, calling for novel strategies with great potency in eliminating cariogenic bacteria and dental plaque that forms, as well as in inhibiting the demineralization of enamel, into an integrated system. Considering the potency of photodynamic therapy in bacteria inactivation and the composition of enamel, we herein report that the novel photodynamic nano hydroxyapatite (nHAP), named Ce6 @QCS/nHAP, was useful for this purpose. Ce6 @QCS/nHAP, comprised of quaternary chitosan (QCS)-coated nHAP loaded with chlorin e6 (Ce6), exhibited good biocompatibility and non-compromised photodynamic activity. In vitro studies revealed that Ce6 @QCS/nHAP could effectively associate with cariogenic Streptococcus mutans (S. mutans), leading to a significant antibacterial effect through photodynamic killing and physical inactivation against the planktonic microbe. Three-dimensional fluorescence imaging suggested that Ce6 @QCS/nHAP exhibited a superior S. mutans biofilm penetration capacity to free Ce6, resulting in effective dental plaque eradiation when light irradiation was applied. The number of surviving bacteria in biofilm was at least 2.8 log units lower in the Ce6 @QCS/nHAP group compared to that in the free Ce6 group. Further, in the S. mutans biofilm-infected artificial tooth model, treatment with Ce6 @QCS/nHAP also resulted in the significant prevention of hydroxyapatite disks from demineralization, with lower percentage of fragmentation and weight loss These data suggest that our photodynamic nanosystem can effectively eradicate dental plaque while also significantly protecting artificial tooth from demineralization, opening up new possibilities in treating bacterium-associated dental caries.

Wrapping collagen-based nanoparticle with macrophage membrane for treating multidrug-resistant bacterial infection

Nowadays, multidrug-resistant (MDR) bacterial infectious diseases has become a thorny issue in the healthcare field. Owning to its intrinsic merits, photodynamic therapy (PDT) shows tremendous strengths in fighting against MDR bacterial infections. However, most photodynamic nanoplatforms exhibit unsatisfactory targeting efficiency towards bacteria and infection site, which may compromise the bactericidal effect of PDT. Herein, we firstly reported a bacteria-targeted collagen-based nanoparticle, named Ce6/Col/MM, for treating methicillin-resistant Staphylococcus aureus (MRSA)-infected wound. Ce6/Col/MM was fabricated by wrapping chlorin e6 (Ce6)-loaded collagen-based nanoparticles with macrophage membrane (MM), showing excellent photodynamic activity and good biocompatibility. In vitro studies demonstrated that Ce6/Col/MM could target to bacteria and then exhibit prominent antibacterial capacity against planktonic MRSA under light irradiation. Furthermore, the treatment of MRSA-infected wound in mice with Ce6/Col/MM plus light illumination resulted in potent bacterial inactivation and accelerated wound healing, accompanied by favorable histological compatibility. Collectively, Ce6/Col/MM with superior targeting ability towards bacteria, effective photodynamic antibacterial potency and minimal safety concerns, might be a powerful bactericidal nanoagent for treating infections caused by MDR bacteria.

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CdTe@CdS quantum dots for labeling and imaging of macrophages in liver frozen section below freezing point

CdTe@CdS core-shell quantum dots with different particle sizes are synthesized by aqueous method, and the coating of CdS shell layer improves the quantum yield (36%→59%) and fluorescence stability (37%→77%) of...