Water-dispersible nanomaterials with superbright photoluminescence (PL) emissions and narrow PL bandwidths are urgently desired for various imaging applications. Herein, for the first time, we prepared ultrasmall organosilica nanodots (OSiNDs) with an average size of ∼2.0 nm and ∼100% green-emitting PL quantum efficiency via a one-step hydrothermal treatment of two commercial reagents (a silane molecule and rose bengal). In particular, the structural reorganization and halide loss of rose bengal during the hydrothermal treatment contribute to the ultrahigh quantum yield and low phototoxicity of OSiNDs. Owing to their low pH-induced precipitation/aggregation property, the as-prepared OSiNDs can be used as excellent lysosomal trackers with many advantages: (1) They have superior lysosomal targeting ability with a Pearson's coefficient of 0.98; (2) The lysosomal monitoring time of OSiNDs is up to 48 h, which is much longer than those of commercial lysosomal trackers (<2 h); (3) They do not disturb the pH environment of lysosomes and can be used to visualize lysosomes in living, fixed, and permeabilized cells; (4) They exhibit intrinsic lysosomal tracking ability without the introduction of lysosome-targeting ligands (such as morpholine) and superior photostability; (5) The easy, cost-effective, and scalable synthetic method further ensures that these OSiNDs can be readily used as exceptional lysosomal trackers. We expect that the ultrasmall OSiNDs with superior fluorescence properties and easily modifiable surfaces could be applied as fluorescent nanoprobes, light-emitting diode phosphor, and anticounterfeiting material, which should be able to promote the preparation and application of silicon-containing nanomaterials.

Hydrogels constitute a group of polymeric materials which can hold a large amount of water in their three-dimensional networks due to their hydrophilic structures. In the past few years, they have been researched for various biomedical applications, such as drug/cell carriers, tissue engineering, and biosensors. Particularly, the hydrogels used as drug delivery systems have shown distinct advantages in phototherapy. This review presents recent advancements of hydrogel's use in phototherapeutic applications by focusing on three kinds of phototherapeutic methods including photodynamic therapy (PDT), photothermal therapy (PTT), and phototherapy-containing combination therapy (PCCT). The applications of these therapies in anticancer and antibacterial fields have also been summarized. We hope that this review will inspire researchers to further develop promising materials for phototherapy applications.

Benefiting from their inherent localized and controlled release properties, hydrogels are ideal delivery systems for therapeutic drugs or nanoparticles. In particular, applications of hydrogels for the delivery and release of photoresponsive drugs or nanoparticles are receiving increasing attention. However, the effect of the hydrogel matrix on the fluorescence emission and singlet oxygen generation efficiency of the embedded photosensitizers (PSs) has not been clarified. Herein, meso-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP) as a water-soluble PS was encapsulated into an injectable hydrogel formed by glycol chitosan and dibenzaldehyde-terminated telechelic poly(ethylene glycol). Compared to free TMPyP solution, the TMPyP encapsulated in the hydrogel exhibits three distinct advantages: (1) more singlet oxygen was generated under the same laser irradiation condition; (2) much longer tumor retention was observed due to the low fluidity of the hydrogel; and (3) the fluorescence intensity of TMPyP was significantly enhanced in the hydrogel due to its decreased self-quenching effect. These excellent characteristics lead to remarkable anticancer efficacy and superior fluorescence emission property of the TMPyP-hydrogel system, promoting the development of imaging-guided photodynamic therapy.

Immunofluorescence staining is a crucial tool for studying the structure and behavior of intracellular proteins and organelles. During the staining process, the permeabilization treatment is usually required to enhance the penetration of a fluorescent antibody into the cells. However, since most of the membrane imaging dyes as well as the membrane lipids will detach from the cell surface after permeabilization, membrane labeling using these dyes is not compatible with immunofluorescence staining. Herein, by linking cholesterol-polyethylene glycol (PEG-Chol) and fluorescein isothiocyanate (FITC) with the amine-rich glycol chitosan (GC), we prepared a multifunctional polymeric construct, GC-PEG Chol-FITC, and realized permeabilization-tolerant plasma membrane imaging. Owing to the presence of abundant amine groups in the labeling reagent and the membrane proteins/lipids, the addition of paraformaldehyde in the fixation step induces the amine-cross-linking between the labeling reagents and the membrane proteins/lipids, thus preventing the detachment of fluorophores from the cell surface after permeabilization. Besides, the large molecular weight effect of the imaging reagent may also account for its antipermeabilization property. Furthermore, by combining immunofluorescence staining with the plasma membrane labeling by GC-PEG Chol-FITC, we simultaneously imaged the plasma membrane and cytoskeletons, and clearly observed metaphase cells and binucleated cells. The concept of using amine-rich polymeric dyes for plasma membrane imaging will inspire the development of more permeabilization-resistant membrane labeling dyes with better performance, which can realize simultaneous membrane and intracellular protein imaging and facilitate the future studies of membrane–intracellular protein interactions.

The goal in this paper is to investigate the efficiency of poly-PLL (Poly-L-lysine)/ Alg (Alginate) vector mediated virus genomic DNA transfection and the virus genomic DNA’s biological activity in vivo. After Pseudorabies virus (PRV) genomic DNA being adhered to the porous СаСО3 particles, PLL and Alg were alternately polymerized on the surface of the porous DNA-СаСО3 particles to 7 layers, which were later dissolved them by EDTA to remove СаСО3 cores; the vectors in which the DNA were coated by poly-PLL/Alg, were harvested to infect the rabbits and observe the replication of viral DNA. Porous СаСО3 particles, which were obtained from the reaction between Na2CO3 and CaCl2, had an efficiency of absorbing DNA 1 µg/mg СаСО3 particles. After being coated by PLL/Alg, microcapsules were obtained with the diameter of 2-4 µm. 10.0 µg of poly-PLL/Alg-PRV DNA microcapsules could cause rabbits’ death by intramuscular injection. The identification of PCR shows that the death was caused by PRV infection. The results indicate that Poly-PLL/Alg microcapsules can mediate efficient transfection of DNA.