Hong Yin Wang

Highly Sensitive and Selective Detection of Dopamine Using One-Pot Synthesized Highly Photoluminescent Silicon Nanoparticles

A simple and highly efficient method for dopamine (DA) detection using water-soluble silicon nanoparticles (SiNPs) was reported. The SiNPs with a high quantum yield of 23.6% were synthesized by using a one-pot microwave-assisted method. The fluorescence quenching capability of a variety of molecules on the synthesized SiNPs has been tested; only DA molecules were found to be able to quench the fluorescence of these SiNPs effectively. Therefore, such a quenching effect can be used to selectively detect DA. All other molecules tested have little interference with the dopamine detection, including ascorbic acid, which commonly exists in cells and can possibly affect the dopamine detection. The ratio of the fluorescence intensity difference between the quenched and unquenched cases versus the fluorescence intensity without quenching (ΔI/I) was observed to be linearly proportional to the DA analyte concentration in the range from 0.005 to 10.0 μM, with a detection limit of 0.3 nM (S/N = 3). To the best of our knowledge, this is the lowest limit for DA detection reported so far. The mechanism of fluorescence quenching is attributed to the energy transfer from the SiNPs to the oxidized dopamine molecules through Förster resonance energy transfer. The reported method of SiNP synthesis is very simple and cheap, making the above sensitive and selective DA detection approach using SiNPs practical for many applications.

Shape-Dependent Radiosensitization Effect of Gold Nanostructures in Cancer Radiotherapy: Comparison of Gold Nanoparticles, Nanospikes, and Nanorods

The shape effect of gold (Au) nanomaterials on the efficiency of cancer radiotherapy has not been fully elucidated. To address this issue, Au nanomaterials with different shapes but similar average size (∼50 nm) including spherical gold nanoparticles (GNPs), gold nanospikes (GNSs), and gold nanorods (GNRs) were synthesized and functionalized with poly(ethylene glycol) (PEG) molecules. Although all of these Au nanostructures were coated with the same PEG molecules, their cellular uptake behavior differed significantly. The GNPs showed the highest cellular responses as compared to the GNSs and the GNRs (based on the same gold mass) after incubation with KB cancer cells for 24 h. The cellular uptake in cells increased in the order of GNPs > GNSs > GNRs. Our comparative studies indicated that all of these PEGylated Au nanostructures could induce enhanced cancer cell-killing rates more or less upon X-ray irradiation. The sensitization enhancement ratios (SERs) calculated by a multitarget single-hit model were 1.62, 1.37, and 1.21 corresponding to the treatments of GNPs, GNSs, and GNRs, respectively, demonstrating that the GNPs showed a higher anticancer efficiency than both GNSs and GNRs upon X-ray irradiation. Almost the same values were obtained by dividing the SERs of the three types of Au nanomaterials by their corresponding cellular uptake amounts, indicating that the higher SER of GNPs was due to their much higher cellular uptake efficiency. The above results indicated that the radiation enhancement effects were determined by the amount of the internalized gold atoms. Therefore, to achieve a strong radiosensitization effect in cancer radiotherapy, it is necessary to use Au-based nanomaterials with a high cellular internalization. Further studies on the radiosensitization mechanisms demonstrated that ROS generation and cell cycle redistribution induced by Au nanostructures played essential roles in enhancing radiosensitization. Taken together, our results indicated that the shape of Au-based nanomaterials had a significant influence on cancer radiotherapy. The present work may provide important guidance for the design and use of Au nanostructures in cancer radiotherapy.

Imaging plasma membranes without cellular internalization: multisite membrane anchoring reagents based on glycol chitosan derivatives

Plasma membrane imaging has received substantial attention due to its capability for dynamically tracing significant biological processes including cell trafficking, vesicle transportation, apoptosis, etc. However, cellular internalization of staining molecules poses challenges to the development of fluorescent dyes to specifically label plasma membranes rather than intracellular organelles. In this work, glycol chitosan, a multifunctional biomaterial derived from natural polymers, was used for the first time to image the plasma membranes based on a strategy of multisite membrane anchoring. A glycol chitosan derivative, glycol chitosan-cholesterol-FITC (Chito-Chol-FITC), was synthesized by using glycol chitosan as the backbone, and PEG-cholesterols and FITC molecules as side chains. The cholesterol groups and FITC molecules serve as hydrophobic anchoring units and fluorescent units, respectively. Benefitting from the strategy, this molecular probe could rapidly stain the cell membrane within 5 min as well as effectively restrain the cellular uptake process-it could tolerate an incubation time of 6 h without substantial cellular internalization. Its imaging performance far exceeds that of the current commercial plasma membrane imaging reagents based on small molecules (such as DiD and FM families), which will be easily internalized by the cells within 10-15 min. The present work shows the biomacromolecular assembly of the glycol chitosan derivative on the cell surface, which may shed new light on the interactions of biomaterials with biological systems. Besides, the multisite membrane anchoring strategy developed herein also provides a novel platform for future cell surface engineering studies.

Plasma membrane activatable polymeric nanotheranostics with self-enhanced light-triggered photosensitizer cellular influx for photodynamic cancer therapy

&NA; To address the issue of low cellular uptake of photosensitizers by cancer cells in photodynamic therapy (PDT), we designed a smart plasma membrane‐activatable polymeric nanodrug by conjugating the photosensitizer protoporphyrin IX (PpIX) and polyethylene glycol (PEG) with glycol chitosan (GC). The as‐prepared GC‐PEG‐PpIX can self‐assemble into core‐shell nanoparticles (NPs) in aqueous solution and the fluorescence of PpIX moieties in the inner core is highly quenched due to strong &pgr;–&pgr; stacking. Interestingly, when encountering plasma membranes, the GC‐PEG‐PpIX NPs can disassemble and stably attach to plasma membranes due to the membrane affinity of PpIX moieties, which effectively suppresses the self‐quenching of PpIX, leading to significantly enhanced fluorescence and singlet oxygen (1O2) production upon laser irradiation. The massively produced 1O2 can compromise the integrity of the plasma membrane, enabling the influx of extracellular nanoagents into cells to promote cell death upon further laser irradiation. Through local injection, the membrane anchored GC‐PEG‐PpIX enables strong physical association with tumor cells and exhibits highly enhanced in vivo fluorescence at the tumor site. Besides, excellent tumor accumulation and prolonged tumor retention of GC‐PEG‐PpIX were realized after intravenous injection, which ensured its effective imaging‐guided PDT. Graphical abstract Figure. No caption available.

One-Step Synthesis of Ultrasmall and Ultrabright Organosilica Nanodots with 100% Photoluminescence Quantum Yield: Long-Term Lysosome Imaging in Living, Fixed, and Permeabilized Cells

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 Pearsons 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.