Xiaokai Chen

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.

Hydrogel-based phototherapy for fighting cancer and bacterial infection

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.摘要水凝胶构成了一类高分子材料, 它们的亲水结构使得其能够在三维网络中保有大量的水. 在过去几年中, 水凝胶在生物医学领域的 应用获得了很大的关注, 如作为药物或细胞的载体、组织工程和生物传感器等. 特别地, 水凝胶作为药物输运系统在光疗中拥有显著优点. 本综述总结了水凝胶在光疗应用中的最新进展, 尤其重点讨论了三种光疗方法(包括光动力治疗、光热治疗和组合治疗)及其在抗癌和抗 菌领域的应用. 我们希望本综述将有助于启发未来的相关研究以进一步拓展这种材料在光疗领域的新应用.

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.

Glutathione-Depleting Gold Nanoclusters for Enhanced Cancer Radiotherapy through Synergistic External and Internal Regulations

The therapeutic performance of cancer radiotherapy is often limited by the overexpression of glutathione (GSH) in tumors and low radiation sensitivity of cancerous cells. To address these issues, the facilely prepared histidine-capped gold nanoclusters (Au NCs@His) were adopted as a radiosensitizer with a high sensitization enhancement ratio of ∼1.54. On one hand, Au NCs@His can inherit the local radiation enhancement property of gold-based materials (external regulation); on the other hand, Au NCs@His can decrease the intracellular GSH level, thus preventing the generated reactive oxygen species (ROS) from being consumed by GSH, and arrest the cells at the radiosensitive G2/M phase (internal regulation).

Quantum Dots for Cancer Therapy and Bioimaging

Quantum dots (QDs) usually refer to very small nanoparticles of only few nanometers in size. The optical and electronic properties of QDs differ from those of larger particles. QDs will emit light of specific frequencies if electricity or light is applied to them, and these frequencies can be precisely tuned by changing the dots’ size, shape, and material, giving rise to many applications. In this chapter, apart from the most common QDs, e.g., the cadmium (Cd)-containing semiconductor QDs, other types of QDs, including silver chalcogenide quantum dots, carbon quantum dots, silicon quantum dots, black phosphorus quantum dots, germanium quantum dots, and polymer dots are also introduced with an emphasis on their cancer therapy and imaging applications.