Triplex hairpin oligosensor for ultrasensitive determination of miRNA-155 as a cancer marker using Si quantum dots and Au nanoparticles

In this study, a new triplex hairpin oligosensor was developed for the determination of a breast cancer biomarker using silicon quantum dots (Si QD) (λex = 370 nm, λem = 482 nm) as donor and gold nanoparticles (GNP) as an acceptor in a FRET (fluorescence resonance energy transfer) mechanism. In the triplex hairpin oligosensor, a triplex-forming oligonucleotide (TFO) labeled with Si QD and a single-strand DNA labeled with GNP form a hairpin shape with a triplex structure at the hairpin stem. In a turn-on mechanism, the triplex hairpin stem is opened in the presence of sequence-specific miRNA-155 which leads to the release of the Si QD-labeled TFO probe and recovery of the fluorescence signal. About 80 % of the fluorescence intensity of the Si QD-TFO is quenched in the triplex hairpin structure of the oligosensor and in the presence of 800 pM miRNA-155, the fluorescence signal recovered to 57.7 % of its initial value. The LOD of about 10 pM was obtained. The designed triplex-based biosensor can discriminate concentrations of breast cancer biomarkers with high selectivity.

Emerging Fluorescent Nanoparticles for Non-Invasive Bioimaging

Fluorescence-based techniques have great potential in the field of bioimaging and could bring tremendous progress in microbiology and biomedicine. The most essential element in these techniques is fluorescent nanomaterials. The use of fluorescent nanoparticles as contrast agents for bioimaging is a large topic to cover. The purpose of this mini-review is to give the reader an overview of biocompatible and biodegradable fluorescent nanoparticles that are emerging nanomaterials for use in fluorescent bioimaging. In addition to the biocompatibility of these nanomaterials, biodegradability is considered a necessity for short-term sustainable bioimaging. Firstly, the main requirements for bioimaging are raised, and a few existing fluorescent nanoprobes are discussed. Secondly, a few inert biocompatible fluorescent nanomaterials for long-term bioimaging that have been, to some extent, demonstrated as fluorescent probes are reviewed. Finally, a few biocompatible and biodegradable nanomaterials for short-term bioimaging that are evolving for bioimaging applications are discussed. Together, these advancements signal a transformative leap toward sustainability and functionality in biomedical imaging.

Putative Adverse Outcome Pathway for Parkinson's Disease-like Symptoms Induced by Silicon Quantum Dots based on In Vivo/Vitro Approaches

Given the commercial proliferation of silicon quantum dots (SiQDs) and their inevitable environmental dispersal, this study critically examines their biological and public health implications, specifically regarding Parkinson's disease. The study investigated the toxicological impact of SiQDs on the onset and development of PD-like symptoms through the induction of ferroptosis, utilizing both in vivo [Caenorhabditis elegans (C. elegans)] and in vitro (SH-SY5Y neuroblastoma cell line) models. Our findings demonstrated that SiQDs, characterized by their stable and water-soluble physicochemical properties, tended to accumulate in neuronal tissues. This accumulation precipitated dopaminergic neurodegeneration, manifested as diminished dopamine-dependent behaviors, and escalated the expression of PD-specific genes in C. elegans. Importantly, the results revealed that SiQDs induced ferritinophagy, a selective autophagy pathway that triggered ferroptosis and resulted in PD-like symptoms, even exacerbating disease progression in biological models. These insights were incorporated into a putatively qualitative and quantitative adverse outcome pathway framework, highlighting the serious neurodegenerative risks posed by SiQDs through ferroptosis pathways. This study provides a multidisciplinary analysis critical for informing policy on the regulation of SiQDs exposure to safeguard susceptible populations and guiding the responsible development of nanotechnologies impacting environmental and public health.

One-Pot Synthesis of Silicon Quantum Dots-Based Fluorescent Nanomaterial and Its Application

Conventionally obtained silicon quantum dots (Si QDs) generally suffer from the disadvantages of a cumbersome preparation process, large fluctuation in the quality of Si QDs, poor water solubility, and aggregation-caused quenching (ACQ) phenomenon. Here we report a facile one-pot strategy to synthesize a novel Si QDs-based fluorescent nanomaterial in which Si QDs are confined into dendritic mesoporous silica, named as SiQDs@DMSNs. The prepared SiQDs@DMSNs, with adjustable particle sizes ranging from 140 to 300 nm, emit blue fluorescence around 410 nm upon excitation by ultraviolet light at a wavelength of 300 nm. It is found that the addition of sodium salicylate (NaSAL) plays a crucial role in the in situ generation of Si QDs. The obtained SiQDs@DMSNs exhibit excellent fluorescence intensity, water solubility, and stability, facilitating easy surface modification, without being limited by the ACQ phenomenon. It is expected to be widely used in many fields such as biosensors, nanomedicines, in vivo imaging, fingerprint identification, and anticounterfeiting labels.

Designing a Hypoxia-Activated Sensing Platform Using an Azo Group-Triggered Reaction with the Formation of Silicon Nanoparticles

Hypoxia is known as a specific signal of various diseases, such as liver fibrosis. We designed a hypoxia-sensitive fluorometric approach that cleaved the azo bond (N═N) in the presence of hypoxia-controlled agents (sodium dithionite and azoreductase). 4-(2-Pyridylazo) resorcinol (Py-N═N-RC) bears a desirable hypoxia-responsive linker (N═N), and its azo bond breakup can only occur in the presence of sodium dithionite and azoreductase and leads to the release of 2,4-dihydroxyaniline, which can react with 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane to generate yellow fluorescent silicon nanoparticles. This approach exhibited high selectivity and sensitivity toward both sodium dithionite and azoreductase over other potential interferences. The mouse liver microsome, which is known to contain azoreductase, was applied and confirmed the feasibility of the designed platform. Py-N═N-RC is expected to be a practical substrate for hypoxia-related biological analyses. Furthermore, silicon nanoparticles were successfully applied for Hela cell imaging owing to their negligible cytotoxicity and superb biocompatibility.

Exploring In Vivo Pulmonary and Splenic Toxicity Profiles of Silicon Quantum Dots in Mice

Silicon-based quantum dots (SiQDs) represent a special class of nanoparticles due to their low toxicity and easily modifiable surface properties. For this reason, they are used in applications such as bioimaging, fluorescent labeling, drug delivery, protein detection techniques, and tissue engineering despite a serious lack of information on possible in vivo effects. The present study aimed to characterize and evaluate the in vivo toxicity of SiQDs obtained by laser ablation in the lung and spleen of mice. The particles were administered in three different doses (1, 10, and 100 mg QDs/kg of body weight) by intravenous injection into the caudal vein of Swiss mice. After 1, 6, 24, and 72 h, the animals were euthanized, and the lung and spleen tissues were harvested for the evaluation of antioxidant enzyme activity, lipid peroxidation, protein expression, and epigenetic and morphological changes. The obtained results highlighted a low toxicity in pulmonary and splenic tissues for concentrations up to 10 mg SiQDs/kg body, demonstrated by biochemical and histopathological analysis. Therefore, our study brings new experimental evidence on the biocompatibility of this type of QD, suggesting the possibility of expanding research on the biomedical applications of SiQDs.

Seeing the Supracolloidal Assemblies in 3D: Unraveling High-Resolution Structures Using Electron Tomography

Transmission electron microscopy (TEM) imaging has revolutionized modern materials science, nanotechnology, and structural biology. Its ability to provide information about materials' structure, composition, and properties at atomic-level resolution has enabled groundbreaking discoveries and the development of innovative materials with precision and accuracy. Electron tomography, single particle reconstruction, and microcrystal electron diffraction techniques have paved the way for the three-dimensional (3D) reconstruction of biological samples, synthetic materials, and hybrid nanostructures at near atomic-level resolution. TEM tomography using a series of two-dimensional (2D) projections has been used extensively in biological science, but in recent years it has become an important method in synthetic nanomaterials and soft matter research. TEM tomography offers unprecedented morphological details of 3D objects, internal structures, packing patterns, growth mechanisms, and self-assembly pathways of self-assembled colloidal systems. It complements other analytical tools, including small-angle X-ray scattering, and provides valuable data for computational simulations for predictive design and reverse engineering of nanomaterials with the desired structure and properties. In this perspective, I will discuss the importance of TEM tomography in the structural understanding and engineering of self-assembled nanostructures with specific emphasis on colloidal capsids, composite cages, biohybrid superlattices with complex geometries, polymer assemblies, and self-assembled protein-based superstructures.

In Vivo Assessment of Hepatic and Kidney Toxicity Induced by Silicon Quantum Dots in Mice

In the last decade, silicon-based quantum dots (SiQDs) have attracted the attention of researchers due to their unique properties for which they are used in medical applications and in vivo imaging. Detection of cytotoxic effects in vivo is essential for understanding the mechanisms of toxicity, a mandatory step before their administration to human subjects. In this context, we aimed to evaluate the in vivo hepatic and renal acute toxicity of SiQDs obtained by laser ablation. The nanoparticles were administrated at different doses (0, 1, 10, and 100 mg of QDs/kg of body weight) by intravenous injection into the caudal vein of Swiss mice. After 1, 6, 24, and 72 h, the animals were euthanatized, and liver and kidney tissues were used in further toxicity tests. The time- and dose-dependent effects of SiQDs on the antioxidant defense system of mice liver and kidney were investigated by quantifying the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase) in correlation with the morphological changes and inflammatory status in the liver and kidneys. The results showed a decrease in the activities of antioxidant enzymes and histopathological changes, except for superoxide dismutase, in which no significant changes were registered compared with the control. Furthermore, the immunohistochemical expression of TNF-α was significant at doses over 10 mg of QDs/kg of body weight and were still evident at 72 h after administration. Our results showed that doses under 10 mg of SiQDs/kg of b.w. did not induce hepatic and renal toxicity, providing useful information for further clinical trials.

Precision nanoengineering for functional self-assemblies across length scales

As nanotechnology continues to push the boundaries across disciplines, there is an increasing need for engineering nanomaterials with atomic-level precision for self-assembly across length scales, i.e., from the nanoscale to the macroscale. Although molecular self-assembly allows atomic precision, extending it beyond certain length scales presents a challenge. Therefore, the attention has turned to size and shape-controlled metal nanoparticles as building blocks for multifunctional colloidal self-assemblies. However, traditionally, metal nanoparticles suffer from polydispersity, uncontrolled aggregation, and inhomogeneous ligand distribution, resulting in heterogeneous end products. In this feature article, I will discuss how virus capsids provide clues for designing subunit-based, precise, efficient, and error-free self-assembly of colloidal molecules. The atomically precise nanoscale proteinic subunits of capsids display rigidity (conformational and structural) and patchy distribution of interacting sites. Recent experimental evidence suggests that atomically precise noble metal nanoclusters display an anisotropic distribution of ligands and patchy ligand bundles. This enables symmetry breaking, consequently offering a facile route for two-dimensional colloidal crystals, bilayers, and elastic monolayer membranes. Furthermore, inter-nanocluster interactions mediated via the ligand functional groups are versatile, offering routes for discrete supracolloidal capsids, composite cages, toroids, and macroscopic hierarchically porous frameworks. Therefore, engineered nanoparticles with atomically precise structures have the potential to overcome the limitations of molecular self-assembly and large colloidal particles. Self-assembly allows the emergence of new optical properties, mechanical strength, photothermal stability, catalytic efficiency, quantum yield, and biological properties. The self-assembled structures allow reproducible optoelectronic properties, mechanical performance, and accurate sensing. More importantly, the intrinsic properties of individual nanoclusters are retained across length scales. The atomically precise nanoparticles offer enormous potential for next-generation functional materials, optoelectronics, precision sensors, and photonic devices.

Nanotechnology for brain tumor imaging and therapy based on π-conjugated materials: state-of-the-art advances and prospects

In contemporary biomedical research, the development of nanotechnology has brought forth numerous possibilities for brain tumor imaging and therapy. Among these, π-conjugated materials have garnered significant attention as a special class of nanomaterials in brain tumor-related studies. With their excellent optical and electronic properties, π-conjugated materials can be tailored in structure and nature to facilitate applications in multimodal imaging, nano-drug delivery, photothermal therapy, and other related fields. This review focuses on presenting the cutting-edge advances and application prospects of π-conjugated materials in brain tumor imaging and therapeutic nanotechnology.

Photostable Cascade-Activatable Peptide Self-Assembly on a Cancer Cell Membrane for High-Performance Identification of Human Bladder Cancer

Missed or residual tumor burden results in high risk for bladder cancer relapse. However, existing fluorescent probes cannot meet the clinical needs because of inevitable photobleaching properties. Performance can be improved by maintaining intensive and sustained fluorescence signals via resistance to intraoperative saline flushing and intrinsic fluorescent decay, providing surgeons with sufficiently clear and high-contrast surgical fields, avoiding residual tumors or missed diagnosis. This study designs and synthesizes a photostable cascade-activatable peptide, a target reaction-induced aggregation peptide (TRAP) system, which can construct polypeptide-based nanofibers in situ on the cell membrane to achieve long-term and stable imaging of bladder cancer. The probe has two parts: a target peptide (TP) targets CD44v6 to recognize bladder cancer cells, and a reaction-induced aggregation peptide (RAP) is introduced, which effectively reacts with the TP via a click reaction to enhance the hydrophobicity of the whole molecule, assembling into nanofibers and further nanonetworks. Accordingly, probe retention on the cell membrane is prolonged, and photostability is significantly improved. Finally, the TRAP system is successfully employed in the high-performance identification of human bladder cancer in ex vivo bladder tumor tissues. This cascade-activatable peptide molecular probe based on the TRAP system enables efficient and stable imaging of bladder cancer.

Two-photon nanoprobes based on bioorganic nanoarchitectonics with a photo-oxidation enhanced emission mechanism

Two-photon absorption (TPA) fluorescence imaging holds great promise in diagnostics and biomedicine owing to its unparalleled spatiotemporal resolution. However, the adaptability and applicability of currently available TPA probes, which act as a critical element for determining the imaging contrast effect, is severely challenged by limited photo-luminescence in vivo. This is particularly a result of uncontrollable aggregation that causes fluorescence quenching, and inevitable photo-oxidation in harsh physiological milieu, which normally leads to bleaching of the dye. Herein, we describe the remarkably enhanced TPA fluorescence imaging capacity of self-assembling near-infrared (NIR) cyanine dye-based nanoprobes (NPs), which can be explained by a photo-oxidation enhanced emission mechanism. Singlet oxygen generated during photo-oxidation enables chromophore dimerization to form TPA intermediates responsible for enhanced TPA fluorescence emission. The resulting NPs possess uniform size distribution, excellent stability, more favorable TPA cross-section and anti-bleaching ability than a popular TPA probe rhodamine B (RhB). These properties of cyanine dye-based TPA NPs promote their applications in visualizing blood circulation and tumoral accumulation in real-time, even to cellular imaging in vivo. The photo-oxidation enhanced emission mechanism observed in these near-infrared cyanine dye-based nanoaggregates opens an avenue for design and development of more advanced TPA fluorescence probes.

Detection and discrimination of pathogenic bacteria with nanomaterials-based optical biosensors: A review

Pathogenic bacteria can pose a great threat to food safety and human health. It is therefore imperative to develop a rapid, portable, and sensitive determination and discrimination method for pathogenic bacteria. Over the past few years, various nanomaterials (NMs) have been employed as desirable nanoprobes because they possess extraordinary properties that can be used for optical signal enabled detection and identification of bacteria. By means of modification, NMs can, depending on different mechanisms, sense targets directly or indirectly, which then provides an essential support for the detection and differentiation of pathogenic bacteria. In this review, recent application of NMs-based optical biosensors for food safety bacterial detection and discrimination is performed, mainly in but not limited to noble metal NMs, fluorescent NMs, and point-of-care testing (POCT). This review also focuses on future trends in bacterial detection and discrimination, and machine learning in performing intelligent rapid detection and multiple accurate identification of bacteria.

Vertically Aligned Nanowires and Quantum Dots: Promises and Results in Light Energy Harvesting

The synthesis of crystals with a high surface-to-volume ratio is essential for innovative, high-performance electronic devices and sensors. The easiest way to achieve this in integrated devices with electronic circuits is through the synthesis of high-aspect-ratio nanowires aligned vertically to the substrate surface. Such surface structuring is widely employed for the fabrication of photoanodes for solar cells, either combined with semiconducting quantum dots or metal halide perovskites. In this review, we focus on wet chemistry recipes for the growth of vertically aligned nanowires and technologies for their surface functionalization with quantum dots, highlighting the procedures that yield the best results in photoconversion efficiencies on rigid and flexible substrates. We also discuss the effectiveness of their implementation. Among the three main materials used for the fabrication of nanowire-quantum dot solar cells, ZnO is the most promising, particularly due to its piezo-phototronic effects. Techniques for functionalizing the surfaces of nanowires with quantum dots still need to be refined to be effective in covering the surface and practical to implement. The best results have been obtained from slow multi-step local drop casting. It is promising that good efficiencies have been achieved with both environmentally toxic lead-containing quantum dots and environmentally friendly zinc selenide.

Luminescent Quantum Dots: Synthesis, Optical Properties, Bioimaging and Toxicity

Luminescent nanomaterials such as semiconductor nanocrystals (NCs) and quantum dots (QDs) attract much attention to optical detectors, LEDs, photovoltaics, displays, biosensing, and bioimaging. These materials include metal chalcogenide QDs and metal halide perovskite NCs. Since the introduction of cadmium chalcogenide QDs to biolabeling and bioimaging, various metal nanoparticles (NPs), atomically precise metal nanoclusters, carbon QDs, graphene QDs, silicon QDs, and other chalcogenide QDs have been infiltrating the nano-bio interface as imaging and therapeutic agents. Nanobioconjugates prepared from luminescent QDs form a new class of imaging probes for cellular and in vivo imaging with single-molecule, super-resolution, and 3D resolutions. Surface modified and bioconjugated core-only and core-shell QDs of metal chalcogenides (MX; M = Cd/Pb/Hg/Ag, and X = S/Se/Te,), binary metal chalcogenides (MInX₂; M = Cu/Ag, and X = S/Se/Te), indium compounds (InAs and InP), metal NPs (Ag, Au, and Pt), pure or mixed precision nanoclusters (Ag, Au, Pt), carbon nanomaterials (graphene QDs, graphene nanosheets, carbon NPs, and nanodiamond), silica NPs, silicon QDs, etc. have become prevalent in biosensing, bioimaging, and phototherapy. While heavy metal-based QDs are limited to in vitro bioanalysis or clinical testing due to their potential metal ion-induced toxicity, carbon (nanodiamond and graphene) and silicon QDs, gold and silica nanoparticles, and metal nanoclusters continue their in vivo voyage towards clinical imaging and therapeutic applications. This review summarizes the synthesis, chemical modifications, optical properties, and bioimaging applications of semiconductor QDs with particular references to metal chalcogenide QDs and bimetallic chalcogenide QDs. Also, this review highlights the toxicity and pharmacokinetics of QD bioconjugates.

Emerging ultrasmall luminescent nanoprobes for in vivo bioimaging

Photoluminescence (PL) imaging has become a fundamental tool in disease diagnosis, therapeutic evaluation, and surgical navigation applications. However, it remains a big challenge to engineer nanoprobes for high-efficiency in vivo imaging and clinical translation. Recent years have witnessed increasing research efforts devoted into engineering sub-10 nm ultrasmall nanoprobes for in vivo PL imaging, which offer the advantages of efficient body clearance, desired clinical translation potential, and high imaging signal-to-noise ratio. In this review, we present a comprehensive summary and contrastive discussion of emerging ultrasmall luminescent nanoprobes towards in vivo PL bioimaging of diseases. We first summarize size-dependent nano-bio interactions and imaging features, illustrating the unique attributes and advantages/disadvantages of ultrasmall nanoprobes differentiating them from molecular and large-sized probes. We also discuss general design methodologies and PL properties of emerging ultrasmall luminescent nanoprobes, which are established based on quantum dots, metal nanoclusters, lanthanide-doped nanoparticles, and silicon nanoparticles. Then, recent advances of ultrasmall luminescent nanoprobes are highlighted by surveying their latest in vivo PL imaging applications. Finally, we discuss existing challenges in this exciting field and propose some strategies to improve in vivo PL bioimaging and further propel their clinical applications.

Recent Advances in Silicon Quantum Dot-Based Fluorescent Biosensors

With the development of nanotechnology, fluorescent silicon nanomaterials have been synthesized and applied in various areas. Among them, silicon quantum dots (SiQDs) are a new class of zero-dimensional nanomaterials with outstanding optical properties, benign biocompatibility, and ultra-small size. In recent years, SiQDs have been gradually utilized for constructing high-performance fluorescent sensors for chemical or biological analytes. Herein, we focus on reviewing recent advances in SiQD-based fluorescent biosensors from a broad perspective and discussing possible future trends. First, the representative progress for synthesizing water-soluble SiQDs in the past decade is systematically summarized. Then, the latest achievement of the design and fabrication of SiQD-based fluorescent biosensors is introduced, with a particular focus on analyte-induced photoluminescence (fluorescence) changes, hybrids of SiQDs with other materials or molecules, and biological ligand-modification methods. Finally, the current challenges and prospects of this field are highlighted.

NIR-Photocontrolled Aqueous RAFT Polymerization with Polymerizable Water-Soluble Zinc Phthalocyanine as Photocatalyst

In order to give an answer for the challenges of long wavelength-photocontrolled radical polymerization in aqueous solutions and to address the shortcomings of conventional near-infrared (NIR) photocatalysts (PCs) that are difficult to subject to post-treatment, we designed and synthesized a series of β-tetra-substituted water-soluble zinc phthalocyanines (β-TS-Zns) as the NIR PCs for reversible addition-fragmentation chain transfer (RAFT) polymerization successfully under irradiation with NIR (λ_max = 730 nm) light at room temperature. Importantly, the NIR PCs can also be designed as polymerizable monomers and covalently loaded on the polymer chains, which are endowed with permanent NIR photocatalysis of the resultant polymers. Moreover, the polymerization can not only be carried out in water but also in phosphate buffer saline (PBS) solution, yielding polymers with controlled molar mass and narrow dispersities (Đ = 1.03-1.25). Therefore, this NIR-photocontrolled aqueous RAFT polymerization system may provide a charming strategy for possible applications in tissue engineering biomaterial in situ benefiting from the high penetration ability of NIR light.

Luminescent Gold Nanoclusters for Bioimaging: Increasing the Ligand Complexity

Fluorescence, and more in general, photoluminescence (PL), presents important advantages for imaging with respect to other diagnostic techniques. In particular, detection methodologies exploiting fluorescence imaging are fast and versatile; make use of low-cost and simple instrumentations; and are taking advantage of newly developed powerful, low-cost, light-based electronic devices, such as light sources and cameras, used in huge market applications, such as civil illumination, computers, and cellular phones. Besides the aforementioned simplicity, fluorescence imaging offers a spatial and temporal resolution that can hardly be achieved with alternative methods. However, the two main limitations of fluorescence imaging for bio-application are still (i) the biological tissue transparency and autofluorescence and (ii) the biocompatibility of the contrast agents. Luminescent gold nanoclusters (AuNCs), if properly designed, combine high biocompatibility with PL in the near-infrared region (NIR), where the biological tissues exhibit higher transparency and negligible autofluorescence. However, the stabilization of these AuNCs requires the use of specific ligands that also affect their PL properties. The nature of the ligand plays a fundamental role in the development and sequential application of PL AuNCs as probes for bioimaging. Considering the importance of this, in this review, the most relevant and recent papers on AuNCs-based bioimaging are presented and discussed highlighting the different functionalities achieved by increasing the complexity of the ligand structure.

Tuning functionalized hexagonal boron nitride quantum dots for full visible-light fluorescence emission

Tunable photoluminescence has been observed in hexagonal boron nitride quantum dots (BNQDs), but the underlying luminescence mechanism remains elusive. In this study, we examine excited-state properties of several functionalized BNQDs models using density functional theory (DFT), time-dependent DFT, and multistate complete active space second-order perturbation theory (MS-CASPT2) methods. Unlike reported graphene quantum dots, photoluminescence of BNQDs is not affected by their sizes (<2.5 nm). Instead, the embedded single sp³ carbon atom connecting different functional groups can tune emission colors of BNQDs, whose emission wavelength cover full range of visible light and even extend toward near-infrared region. Further analysis reveals that both exciton self-trapping and electron-hole separation decrease HOMO-LUMO energy gaps, leading to large Stokes shifts. Moreover, uneven and even hybridizations induce blue- and red-shifted emission spectra. These findings provide novel insights into full-spectrum emission of BNQDs modified with functional groups.

Biocompatible, Biodegradable, and Improved Fluorescent Silicon Quantum Dots for Zebrafish Imaging

One of the greatest benefits of nanomedicine elucidated to date includes the non-invasive tracking and monitoring of living organisms by the selective uptake of harmless metallic nanoparticles. Several nanoscale probes have been employed for biomolecular imaging. Among them, fluorescent nanoscale silicon materials have been recently established with a strong and safe potential for bioimaging and biosensing applications due to their bright fluorescence coupled with strong photostability, biocompatibility and negligible toxicity. Herein, we developed high-quality silicon nanomaterials (4–5 nm; SiNPs) as biological fluorescent probes for bioimaging of living organisms through an easy aquatic synthesis method with a quantum yield of ∼8%. In this regard, we report that the presently synthesized SiNPs-based sensors/probes are attractive materials for solvent-based fluorescence measurements and are biocompatible, non-toxic, highly photo-stable and pH stable. Most importantly, their fluorescence lifetime is much longer than that of native probes in living cells. Thus, these presently formulated SiNPs are improved fluorescent probes for in vivo biological imaging in zebra fish embryos as well as numerous other living organisms and, thus, should be further studied.

Nanoparticle-based single molecule fluorescent probes

Single molecule fluorescent probes have attracted considerable attention duet to their ultimate sensitivity, fast response, low sample consumption, and high signal-to-noise ratio. Nanoparticles with outstanding optical properties make them perfect candidates for probes in application of single molecule detection. In this review, we focus on various kinds of nanoparticles acting as single molecule fluorescent probes, including quantum dots, upconverting fluorescent nanoparticles, carbon dots, single-wall carbon nanotubes, fluorescent nanodiamonds, polymeric nanoparticles, nanoclusters, and metallic nanoparticles. Optical properties of various nanoparticles and their recent application in single molecule fluorescent probes are explored. How nanoparticles boost the sensitivity of detection is emphasized in combination with different sensing strategies. Future trends of nanoparticles in single molecule detection are also discussed. We hope this review can provide practical guidance for researchers who work on nanoparticle-based single molecule fluorescent probes.

Synthesis of Renal-Clearable Multicolor Fluorescent Silicon Nanodots for Tumor Imaging and In Vivo H2O2 Profiling

Fluorescent silicon nanodots have shown great prospects for bioimaging and biosensing applications. Although various fluorescent silicon-containing nanodots (SiNDs) have been developed, there are few reports about renal-clearable multicolor SiNDs. Herein, renal-clearable multicolor fluorescent SiNDs are synthesized by using silane molecules and organic dyes through a facile one-step hydrothermal method. The fluorescence of the resulting SiNDs can be tuned to blue (bSiNDs), green (gSiNDs), and red (rSiNDs) by simply changing the categories of silane reagents or dye molecules. The as-prepared SiNDs exhibit strong fluorescence with a quantum yield up to 72%, excellent photostability, and good biocompatibility with 12 h renal clearance rate as high as 86% ID. These properties enabled the SiNDs for tumor fluorescence imaging and H₂O₂ imaging in living cells and tissue through in situ reduction reaction-lighted fluorescence of the nanoprobe. Our results provide an invaluable methodology for the synthesis of renal-clearable multicolor SiNDs and their potential applications for fluorescence imaging and biomarker sensing. These SiNDs are also promising for various biological and biomedical applications.

Water-Soluble Silicon Quantum Dots toward Fluorescence-Guided Photothermal Nanotherapy

We report carboxy-terminated silicon quantum dots (SiQDs) that exhibit high solubility in water due to the high molecular coverage of surface monolayers, bright light emission with high photoluminescence quantum yields (PLQYs), long-term stability in the PL property for monitoring cells, less toxicity to the cells, and a high photothermal response. We prepared water-soluble SiQDs by the thermal hydrosilylation of 10-undecenoic acid on their hydrogen-terminated surfaces, provided by the thermal disproportionation of triethoxysilane hydrolyzed at pH 3 and subsequent hydrofluoric etching. The 10-undecanoic acid-functionalized SiQDs (UA:SiQDs) showed long-term stability in hydrophilic solvents including ethanol and water (pH 7). We assess their interaction with live cells by means of cellular uptake, short-term toxicity, and, for the first time, long-term cytotoxicity. Results show that UA:SiQDs are potential candidates for theranostics, with their good optical properties enabling imaging for more than 18 days and a photothermal response having a 25.1% photothermal conversion efficiency together with the direct evidence of cell death by laser irradiation. UA:SiQDs have low cytotoxicity with full viability of up to 400 μg/mL for the short term and a 50% cell viability value after 14 days of incubation at a 50 μg/mL concentration.

Shell-Isolated Assembly of Atomically Precise Nanoclusters on Gold Nanorods for Integrated Plasmonic-Luminescent Nanocomposites

In this work, we integrate atomically precise noble metal nanoclusters (NCs) on gold nanorods (AuNRs) to create hybrid plasmonic-luminescent nanomaterials. Initially, we assemble luminescent Ag₂₉(LA)₁₂ NC (LA = lipoic acid) to silica shell-encapsulated AuNRs. The resulting nanostructure shows plasmon-enhanced luminescence in aqueous medium as well as in the solid state. Atomic precision of the fluorophores used in this case allows detailed characterization of individual nanocomposites by diverse techniques, including transmission electron microscopy (TEM) and 3D electron tomographic reconstruction. We extend this strategy to prepare similar structures with gold NC protected with bovine serum albumin (Au₃₀BSA). These two examples demonstrate the generic nature of the present strategy in preparing plasmonic-luminescent hybrid nanostructures using atomically precise NCs.

Visible-light and near-infrared fluorescence and surface-enhanced Raman scattering point-of-care sensing and bio-imaging: a review

This review article deals with the concepts, principles and applications of visible-light and near-infrared (NIR) fluorescence and surface-enhanced Raman scattering (SERS) in in vitro point-of-care testing (POCT) and in vivo bio-imaging. It has discussed how to utilize the biological transparency windows to improve the penetration depth and signal-to-noise ratio, and how to use surface plasmon resonance (SPR) to amplify fluorescence and SERS signals. This article has highlighted some plasmonic fluorescence and SERS probes. It has also reviewed the design strategies of fluorescent and SERS sensors in the detection of metal ions, small molecules, proteins and nucleic acids. Particularly, it has provided perspectives on the integration of fluorescent and SERS sensors into microfluidic chips as lab-on-chips to realize point-of-care testing. It has also discussed the design of active microfluidic devices and non-paper- or paper-based lateral flow assays for in vitro diagnostics. In addition, this article has discussed the strategies to design in vivo NIR fluorescence and SERS bio-imaging platforms for monitoring physiological processes and disease progression in live cells and tissues. Moreover, it has highlighted the applications of POCT and bio-imaging in testing toxins, heavy metals, illicit drugs, cancers, traumatic brain injuries, and infectious diseases such as COVID-19, influenza, HIV and sepsis.

Tumor Diagnosis and Therapy Mediated by Metal Phosphorus-Based Nanomaterials

Metal phosphorus-based nanomaterials (Metal-P NMs) including metal phosphate nanomaterials, metal phosphide nanomaterials, and metal-black phosphorus (Metal-BP) nanocomposite are widely used in the field of biomedicine owing to their excellent physical and chemical properties, biocompatibility, and biodegradability. In recent years, metal phosphate nanomaterials and Metal-BP nanocomposite acted as medicine delivery system have made breakthroughs in tumor diagnosis including magnetic resonance imaging, fluorescence imaging, photoacoustic imaging, nuclear imaging, and therapies including chemotherapy, gene therapy, photothermal therapy, photodynamic therapy, and radiation therapy. Metal phosphate nanomaterials have good biodegradability, especially calcium-based metal phosphate nanomaterials can be dissolved into nontoxic ions and participate in the metabolisms of normal organs. Compared with metal phosphate nanomaterials, metal phosphide nanomaterials have excellent optical, magnetic, and catalytic properties, which can be used as multifunctional diagnostic nanoplatforms and therapeutic agents for chemodynamic therapy, photothermal therapy, or immunotherapy. The latest developments in Metal-P NMs, covering the range of preparation methods and biological applications, such as serving as drug carriers, tumor diagnosis, and therapy, are focused. All in all, the current trends, key issues, future prospects and challenges of Metal-P NMs are concluded and discussed, which are important for the development of this research field and shining more lights on this direction.

COOH-Terminated Silicon Quantum Dots as a Highly Efficient Drug Nanocarrier for Targeted Tumor Cell Imaging

Fluorescent silicon quantum dots (SiQDs) characterized by exceptional photostability and colloidal robustness as well as beneficial biocompatibility are fast becoming new pharmaceutical nanocarriers. With a view to efficiently loading cisplatin (CDDP) onto SiQDs, carboxylate group (COOH) terminated SiQDs were imperative because of chelate formation with CDDP. In this work, we employed a facial microwave irradiation route for rapidly synthesizing high-quality COOH-SiQDs through the use of 3-aminopropyl trimethoxy silane (APTMS) molecules to fulfil the role of silicon precursor and maleic acid (MA) as the agent for facilitating reduction. The SiQDs showed blue fluorescence with an associated photoluminescence quantum yield (PLQY) of 40.2%, the size of which was small at 3.2 ±0.6 nm, and long-lasting stability (an extensive range in pH (4-12) and concentrations of electrolytes reaching 3 Molarity of a solution of sodium chloride). As nanocarriers, carboxylic acids chelation generated a high loading of CDDP onto SiQDs (drug loading capacity, DLC up to 32.2% at pH = 9) and a drug release of CDDP up to 57.6% at pH = 5. Furthermore, the MTT assays demonstrated the non or low cytotoxicity of SiQDs and the role of the controlled release of SiQD-CDDP Finally, the prepared SiQD-CDDP were used for cell imaging, and further targeted labeling of some tumors after folic acid (FA) conjugation. These characteristics allow for the deployment of SiQDs as a highly efficient nanocarrier that facilitate the delivery of clinical drugs for the future.

Luminescent copper indium sulfide (CIS) quantum dots for bioimaging applications

Copper indium sulfide (CIS) quantum dots are ideal for bioimaging applications, by being characterized by high molar absorption coefficients throughout the entire visible spectrum, high photoluminescence quantum yield, high tolerance to the presence of lattice defects, emission tunability from the red to the near-infrared spectral region by changing their dimensions and composition, and long lifetimes (hundreds of nanoseconds) enabling time-gated detection to increase signal-to-noise ratio. The present review collects: (i) the most common procedures used to synthesize stable CIS QDs and the possible strategies to enhance their colloidal stability in aqueous environment, a property needed for bioimaging applications; (ii) their photophysical properties and parameters that affect the energy and brightness of their photoluminescence; (iii) toxicity and bioimaging applications of CIS QDs, including tumor targeting, time-gated detection and multimodal imaging, as well as theranostics. Future perspectives are analyzed in view of advantages and potential limitations of CIS QDs compared to most traditional QDs.

Construction of Robust Cadmium-Free Cu-In-Zn-S Nanocrystals and Polyfluorene Derivatives Hybrid Emissive Layer for Stable Electroluminescent White Light-Emitting Devices

Combination of the merit of inorganic nanocrystals (NCs) and solution-processed conjugated polymer is a convenient strategy to obtain stable and efficient electroluminescent white-light-emitting diodes (el-WLEDs). In this work, an el-WLED was fabricated on the basis of Cd-free Cu-In-Zn-S (CIZS)/ZnS NCs blending with polyfluorene derivative poly[4-(octyloxy)-9,9-diphenylfluoren-2,7-diyl]-co-[5-(octyloxy)-9,9-diphenylfluoren-2,7-diyl] (PODPF), which exhibited a stable white light emission with a color rendering index value of 85. Meanwhile, it had a stable spectrum under high voltage due to the extremely weak energy transfer between PODPF and CIZS/ZnS NCs. To further improve the device performance, PC₉O₄ was used to replace PODPF, which presented better solubility and smoother film-forming properties. Thus, the maximum external quantum efficiency (EQE) of the optimized el-WLED was increased by 221% while maintaining a stable spectrum under high voltage. This work may provide a great foundation on color mixing cadmium-free el-WLEDs.

Nanomaterial-Based Dual-Emission Ratiometric Fluorescent Sensors for Biosensing and Cell Imaging

Owing to the unique optophysical properties of nanomaterials and their self-calibration characteristics, nanomaterial-based (e.g., polymer dots (Pdots) quantum dots (QDs), silicon nanorods (SiNRs), and gold nanoparticle (AuNPs), etc.) ratiometric fluorescent sensors play an essential role in numerous biosensing and cell imaging applications. The dual-emission ratiometric fluorescence technique has the function of effective internal referencing, thereby avoiding the influence of various analyte-independent confounding factors. The sensitivity and precision of the detection can therefore be greatly improved. In this review, the recent progress in nanomaterial-based dual-emission ratiometric fluorescent biosensors is systematically summarized. First, we introduce two general design approaches for dual-emission ratiometric fluorescent sensors, involving ratiometric fluorescence with changes of one response signal and two reversible signals. Then, some recent typical examples of nanomaterial-based dual-emission ratiometric fluorescent biosensors are illustrated in detail. Finally, probable challenges and future outlooks for dual-emission ratiometric fluorescent nanosensors for biosensing and cell imaging are rationally discussed.

Photoluminescent Nanoparticles for Chemical and Biological Analysis and Imaging

Research related to the development and application of luminescent nanoparticles (LNPs) for chemical and biological analysis and imaging is flourishing. Novel materials and new applications continue to be reported after two decades of research. This review provides a comprehensive and heuristic overview of this field. It is targeted to both newcomers and experts who are interested in a critical assessment of LNP materials, their properties, strengths and weaknesses, and prospective applications. Numerous LNP materials are cataloged by fundamental descriptions of their chemical identities and physical morphology, quantitative photoluminescence (PL) properties, PL mechanisms, and surface chemistry. These materials include various semiconductor quantum dots, carbon nanotubes, graphene derivatives, carbon dots, nanodiamonds, luminescent metal nanoclusters, lanthanide-doped upconversion nanoparticles and downshifting nanoparticles, triplet-triplet annihilation nanoparticles, persistent-luminescence nanoparticles, conjugated polymer nanoparticles and semiconducting polymer dots, multi-nanoparticle assemblies, and doped and labeled nanoparticles, including but not limited to those based on polymers and silica. As an exercise in the critical assessment of LNP properties, these materials are ranked by several application-related functional criteria. Additional sections highlight recent examples of advances in chemical and biological analysis, point-of-care diagnostics, and cellular, tissue, and in vivo imaging and theranostics. These examples are drawn from the recent literature and organized by both LNP material and the particular properties that are leveraged to an advantage. Finally, a perspective on what comes next for the field is offered.

Construction of a Dye-Sensitized and Gold Plasmon-Enhanced Cathodic Photoelectrochemical Biosensor for Methyltransferase Activity Assay

DNA methyltransferases may function as important biomarkers of cancers and genetic diseases. Herein, we develop a dye-sensitized and gold plasmon-enhanced cathodic photoelectrochemical (PEC) biosensor on the basis of p-type covalent organic polymers (COPs) for the signal-on measurement of M.SssI methyltransferase (M.SssI MTase). The cathodic PEC biosensor is constructed by the in situ growth of p-type COP films onto a glass coated with indium tin oxide and the subsequent assembly of biotin- and HS-labeled double-stranded DNA (dsDNA) probes onto the COP film via biotin-streptavidin interaction. The dsDNA probe contains the recognition sequence of M.SssI MTase. The COP thin films possess a porous ultrathin nanosheet structure with abundant active sites, facilitating the generation of a high photocurrent compared with the hydrothermally synthesized ones. The presence of DNA methyltransferases can prevent the digestion of restriction endonuclease HpaII, consequently inducing the introduction of gold nanoparticles (AuNPs) to the dsDNA probes via the S-Au bond and the intercalation of rhodamine B (RhB) into the DNA grooves to produce a high photocurrent due to the dye-photosensitized enhancement and AuNP-mediated surface plasmon resonance. However, in the absence of M.SssI MTase, HpaII digests the dsDNA probes, and neither AuNPs nor RhB can be introduced onto the electrode surface, leading to a low photocurrent. This cathodic PEC biosensor possesses high sensitivity and good selectivity, and it can screen the inhibitors and detect M.SssI MTase in serum as well.

Luminescent Gold Nanocluster-Methylcellulose Composite Optical Fibers with Low Attenuation Coefficient and High Photostability

Because of their lightweight structure, flexibility, and immunity to electromagnetic interference, polymer optical fibers (POFs) are used in numerous short-distance applications. Notably, the incorporation of luminescent nanomaterials in POFs offers optical amplification and sensing for advanced nanophotonics. However, conventional POFs suffer from nonsustainable components and processes. Furthermore, the traditionally used luminescent nanomaterials undergo photobleaching, oxidation, and they can be cytotoxic. Therefore, biopolymer-based optical fibers containing nontoxic luminescent nanomaterials are needed, with efficient and environmentally acceptable extrusion methods. Here, such an approach for fibers wet-spun from aqueous methylcellulose (MC) dispersions under ambient conditions is demonstrated. Further, the addition of either luminescent gold nanoclusters, rod-like cellulose nanocrystals or gold nanocluster-cellulose nanocrystal hybrids into the MC matrix furnishes strong and ductile composite fibers. Using cutback attenuation measurement, it is shown that the resulting fibers can act as short-distance optical fibers with a propagation loss as low as 1.47 dB cm^-1 . The optical performance is on par with or even better than some of the previously reported biopolymeric optical fibers. The combination of excellent mechanical properties (Young's modulus and maximum strain values up to 8.4 GPa and 52%, respectively), low attenuation coefficient, and high photostability makes the MC-based composite fibers excellent candidates for multifunctional optical fibers and sensors.

Promoting reactive oxygen species generation: a key strategy in nanosensitizer-mediated radiotherapy

The radiotherapy enhancement effect of numerous nanosensitizers is based on the excessive production of reactive oxygen species (ROS), and only a few systematic reviews have focused on the key strategy in nanosensitizer-mediated radiotherapy. To clarify the mechanism underlying this effect, it is necessary to understand the role of ROS in radiosensitization before clinical application. Thus, the source of ROS and their principle of tumor inhibition are first introduced. Then, nanomaterial-mediated ROS generation in radiotherapy is reviewed. The double-edged sword effect of ROS and the potential dangers they may pose to cancer patients are subsequently addressed. Finally, future perspectives regarding ROS-regulated nanosensitizer applications and development are discussed.

Photoluminescent Nanomaterials for Medical Biotechnology

Creation of various photoluminescent nanomaterials has significantly expanded the arsenal of approaches used in modern biomedicine. Their unique photophysical properties can significantly improve the sensitivity and specificity of diagnostic methods, increase therapy effectiveness, and make a theranostic approach to treatment possible through the application of nanoparticle conjugates with functional macromolecules. The most widely used nanomaterials to date are semiconductor quantum dots; gold nanoclusters; carbon dots; nanodiamonds; semiconductor porous silicon; and up-conversion nanoparticles. This paper considers the promising groups of photoluminescent nanomaterials that can be used in medical biotechnology: in particular, for devising agents for optical diagnostic methods, sensorics, and various types of therapy.

Derivation of Luminescent Mesoporous Silicon Nanocrystals from Biomass Rice Husks by Facile Magnesiothermic Reduction

High-quality silicon (Si) nanocrystals that simultaneously had superior mesoporous and luminescent characteristics were derived from sticky, red, and brown rice husks via the facile and cost-effective magnesiothermic reduction method. The Si nanocrystals were confirmed to comprise an aggregated morphology with spherical nanocrystals (e.g., average sizes of 15-50 nm). Due to the surface functional groups formed at the nanocrystalline Si surfaces, the Si nanocrystals clearly exhibited multiple luminescence peaks in visible-wavelength regions (i.e., blue, green, and yellow light). Among the synthesized Si nanocrystals, additionally, the brown rice husk (BRH)-derived Si nanocrystals showed to have a strong UV absorption and a high porosity (i.e., large specific surface area: 265.6 m2/g, small average pore diameter: 1.91 nm, and large total pore volume: 0.5389 cm3/g). These are indicative of the excellent optical and textural characteristics of the BRH-derived Si nanocrystals, compared to previously reported biomass-derived Si nanocrystals. The results suggest that the biomass BRH-derived Si nanocrystals hold great potential as an active source material for optoelectronic devices as well as a highly efficient catalyst or photocatalyst for energy conversion devices.

Controlled synthesis of fluorescent carbon materials with the assistance of capillary electrophoresis

Carbon nanodots (CNDs) have been widely applied in variety of fields, while some evidences indicate their components may be complicated. In this work, capillary electrophoresis (CE) was used to evaluate the effect of synthetic conditions of fluorescent CNDs prepared through the hydrothermal method using citric acid (CA) and Triaminoguanidinium chloride (TG_Cl) as the starting materials. The results indicated that the fluorescent components of the products were affected by the ratio of the starting materials, the reaction temperature and reaction time. Under selected conditions, a ratio of TG_Cl to CA of 1:6, the reaction at 180 °C for 3 h, the product contains more than 4 fluorescent components with similar optical properties. CNDs were used for the determination of Cr(VI) in environmental samples with recoveries ranging in 95.3-107%, and the mechanism was also confirmed.

Electrochemiluminescence ultrasensitive immunoassay for carbohydrate antigen 125 based on AgInS2/ZnS nanocrystals

We developed a near-infrared (NIR) electrochemiluminescence (ECL) immunosensor for sensitively and selectively determining carbohydrate antigen 125 (CA125) with toxic-element-free and environmental-friendly AgInS₂/ZnS nanocrystals (NCs) as tags. The core/shell-structured AgInS₂/ZnS NCs not only can be conveniently prepared via an aqueous synthetic procedure, but also has high photoluminescence quantum yield (PLQY) of up to 61.7%, highly monodispersed, water-soluble, and desired biological compatibility. As AgInS₂/ZnS NCs can be oxidized via electrochemically injecting holes into their valence band at + 0.84 V, both the monodispersed AgInS₂/ZnS NCs in solution and the surface-confined AgInS₂/ZnS NCs immobilized in sandwich-typed immuno-complexes with CA125 as analyte can exhibit efficient oxidative-reduction ECL around 695 nm under physiological conditions with the presence of tri-n-propylamine (TPrA). The ECL intensity from the AgInS₂/ZnS NCs immobilized in sandwich-typed immuno-complexes increases linearly and selectively with an increased concentration of CA125 from 5 × 10^-6 to 5 × 10^-3 U/mL, and limit of detection (LOD) was 1 × 10^-6 U/mL (S/N = 3). This reliable platform can provide an effective detection method in the early diagnosis and treatment of ovarian cancer.

Ratiometric Fluorescence Detection of DNA Based on the Inner Filter Effect of Ru(bpy)2(dppx)2+ toward Silicon Nanodots

A ratiometric DNA sensor was developed based on fluorescent silicon nanodots (SiNDs) and Ru(bpy)₂(dppx)²⁺. The absorption spectrum of Ru(bpy)₂(dppx)²⁺ has significant overlap with both the excitation and emission spectra of SiNDs. Therefore, fluorescence quenching of Ru(bpy)₂(dppx)²⁺ toward SiNDs can occur on account of the strong inner filter effect. The effect of quenching is not influenced by the specific binding between Ru(bpy)₂(dppx)²⁺ and DNA. Fluorescence turn-on detection of DNA can be performed employing Ru(bpy)₂(dppx)²⁺ and SiNDs as the response and reference signals, respectively. Using SiND-Ru(bpy)₂(dppx)²⁺, a convenient, sensitive, rapid, and precise method could be developed for DNA detection. In aqueous solutions, the I ₆₀₁/I ₄₄₈ fluorescence intensity ratio of SiND-Ru(bpy)₂(dppx)²⁺ increases linearly in the DNA concentration range of 20-1500 nM. The limit of detection and precision of the method is 4.3 nM and 3.5% (50 nM, n = 13), respectively. The ratiometric sensor was tested for visual detection of trace DNA. Moreover, this method was found suitable for the ratiometric detection of DNA in a simulated sample and a human serum sample, and the recoveries were in the range of 98-119%.

An electrically driven single microribbon based near-infrared exciton–polariton light-emitting diode

An electrically driven exciton–polariton NIR-LED involving an n-ZnO:Ga microribbon/p-GaAs heterojunction was achieved. The Rabi splitting is measured to be 109 meV.

Recent advances in bioelectronics chemistry

Research in bioelectronics is highly interdisciplinary, with many new developments being based on techniques from across the physical and life sciences. Advances in our understanding of the fundamental chemistry underlying the materials used in bioelectronic applications have been a crucial component of many recent discoveries. In this review, we highlight ways in which a chemistry-oriented perspective may facilitate novel and deep insights into both the fundamental scientific understanding and the design of materials, which can in turn tune the functionality and biocompatibility of bioelectronic devices. We provide an in-depth examination of several developments in the field, organized by the chemical properties of the materials. We conclude by surveying how some of the latest major topics of chemical research may be further integrated with bioelectronics.

One-pot synthesis of folic acid modified carbonized polymer dots with red emittision for selective imaging of cancer cells

Carbonized polymer dots (CPDs), as a novel fluorescent material, have broad application prospects in the fields of bio-imaging, bio-sensors, disease diagnosis and photovoltaic devices due to their low cost, low toxicity, easy modification and little environmental impact. In this paper, folic acid (FA) modified CPDs (FA-CPDs) are synthesized from p-Phenylenediamine (p-PD) and FA molecules using a traditional one pot hydrothermal reaction in order to detect cancer cells containing a folate receptor (FR). The synthesized FA-CPDs were characterized by transmission electron microscopy, Fourier transfrom infrared spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, UV-vis and fluorescence techniques. The red fluorescence emission is realized by doping phosphorus atoms into the carbonized polymer. Upon excitation at 513 nm, the maximum emission wavelength of FA-CPDs aqueous solution was obtained at 613 nm. Moreover, the as-prepared FA-CPDs exhibit excellent excitation-independent behavior and good stability with high quantum yield (QY) at about 30.6%. The binding of FA-CPDs with FRs on cancer cells produces target recognition and enters the cells through endocytosis. Additionally, it is worth noting that FA-CPDs have good biocompatibility and imaging in HeLa cells has been successfully achieved. Therefore, our FA-CPDs have potential applications as biocompatibility probes for cancer diagnosis and treatment.

Toxicity of different types of quantum dots to mammalian cells in vitro: An update review

Currently, there are a great quantity type of quantum dots (QDs) that has been developed by researchers. Depending on the core material, they can be roughly divided into cadmium, silver, indium, carbon and silicon QDs. And studies on the toxicity of QDs are also increasing rapidly, but in vivo tests in model animals fail to reach a consistent conclusion. Therefore, we review the literatures dealing with the cytotoxicity of QDs in mammalian cells in vitro. After a short summary of the application characteristics of five types of QDs, the fate of QDs in cells will be discussed, ranging from the uptake, transportation, sublocation and excretion. A substantial part of the review will be focused on in vitro toxicity, in which the type of QDs is combined with their adverse effect and toxic mechanism. Because of their different luminescent properties, different subcellular fate, and different degree of cytotoxicity, we provide an overview on the balance of optical stability and biocompatibility of QDs and give a short outlook on future direction of cytotoxicology of QDs.