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Carbon-based drug delivery systems have attracted great interest because of their excellent photothermal conversion capability and high specific surface area for drug loading. Herein, we report a multifunctional nanoplatform based on hyaluronic acid (HA)-modified and graphene quantum dot (GQD)-gated hollow mesoporous carbon nanoparticle (HMCN) for anticancer drug encapsulation and targeted chemo-photothermal therapy of CD44 receptor-overexpressed cancer cells. In this design, HMCN was not only used as a nanocarrier with high drug loading content to achieve chemotherapy, but also as a near-infrared absorbing agent to realize photothermal therapy. GQDs could not only prevent premature drug release during blood circulation, but also enhance the chemo-photothermal therapeutic efficacy for complete tumor growth suppression. After being modified with HA, the HA-HMCN(DOX)@GQDs could specifically target cancer cells. As expected, the as-prepared HMCN exhibited high doxorubicin (DOX)-loading capacity of 410 mg/g and excellent light-to-heat conversion property. The DOX was released from HA-HMCN(DOX)@GQDs in a near-infrared laser and pH stimuli-responsive manner, which could enhance the therapeutic effect. In vitro cell biological experimental results confirmed that the nanoplatform possesses excellent biocompatibility, specifically target CD44 receptor-overexpressing human cervical carcinoma HeLa cells, and has remarkable synergistic chemo-photothermal killing capacity. The in vivo therapeutic studies in HeLa xenografts also showed negligible toxicity of HA-HMCN@GQDs and complete inhibition of tumor growth of HA-HMCN(DOX) @GQDs with near-infrared irradiation. The excellent therapeutic effects demonstrated in vitro and in vivo suggested the HMCN-based nanoplatform holds potential for efficient dual-responsive targeting drug delivery and synergistic chemo-photothermal therapy.

Carbon quantum dots are the materials of a new era with astonishing properties such as high photoluminescence, chemical tuneability and high biocompatibility. Since their discovery, carbon quantum dots have been described as nanometric high-fluorescent carbon nanoparticles, but this definition has become weaker year after year. Nowadays, the classification and the physical explanation of carbon quantum dots optical properties and their chemical structure remain matter of debate. In this review, we provide a clear discussion on these points, providing a starting point for the rationalization of their classification and a comprehensive view on the optical and chemical features of carbon quantum dots.

With suppressed photon scattering and diminished autofluorescence, in vivo fluorescence imaging in the 1,500- to 1,700-nm range of the near-IR (NIR) spectrum (NIR-IIb window) can afford high clarity and deep tissue penetration. However, there has been a lack of NIR-IIb fluorescent probes with sufficient brightness and aqueous stability. Here, we present a bright fluorescent probe emitting at ∼1,600 nm based on core/shell lead sulfide/cadmium sulfide (CdS) quantum dots (CSQDs) synthesized in organic phase. The CdS shell plays a critical role of protecting the lead sulfide (PbS) core from oxidation and retaining its bright fluorescence through the process of amphiphilic polymer coating and transferring to water needed for imparting aqueous stability and compatibility. The resulting CSQDs with a branched PEG outer layer exhibited a long blood circulation half-life of 7 hours and enabled through-skin, real-time imaging of blood flows in mouse vasculatures at an unprecedented 60 frames per second (fps) speed by detecting ∼1,600-nm fluorescence under 808-nm excitation. It also allowed through-skin in vivo confocal 3D imaging of tumor vasculatures in mice with an imaging depth of ∼1.2 mm. The PEG-CSQDs accumulated in tumor effectively through the enhanced permeation and retention effect, affording a high tumor-to-normal tissue ratio up to ∼32 owing to the bright ∼1,600-nm emission and nearly zero autofluorescence background resulting from a large ∼800-nm Stoke’s shift. The aqueous-compatible CSQDs are excreted through the biliary pathway without causing obvious toxicity effects, suggesting a useful class of ∼1,600-nm emitting probes for biomedical research.

The bio-imaging technology is one of the most significant modern applications used in several fields, including early diagnosis of many illnesses that are most important diseases facing humanity and other vital uses. The primary advancement in nanotechnology is the creation of innovative fluorescence probes called quantum dots (QDs). The use of molecular tagging in research, in vivo, and in vitro studies is revolutionized by quantum dots. The application of QD indicates conversion in natural imaging and photography has demonstrated extraordinary appropriateness in bio-imaging, the discovery of novel drugs, and delivery of targeted genes, biosensing, photodynamic therapy, and diagnosis. New potential methods of early cancer detection and treatment management are being researched as a result of the special physical and chemical characteristics of QD probes. The bio-imaging technique depends on the fluorescent emission of the used materials, which is paired with living cells that are easy to see it in 3D without any surgical intervention. Therefore, the use of QDs many types that have unique and appropriate properties for use in that application; In terms of fluorescent emission strength, duration and luminosity.This review article displays some methods of preparation for QDs nanomaterials and the devices used in this. In addition, it presentssome of challenges that must be avoided for the possibility of using them in the bio-imaging field; as toxicity, bio-compatibility, and hydrophilization. It’s reviewed some of the devices that use QDs in bio-imaging technique, the QDs application in cell analysis-imaging, and QDs application in vivo imaging.

This is the first book to specifically focus on semiconductor nanocrystals, and address their synthesis and assembly, optical properties and spectroscopy, and potential areas of nanocrystal-based devices.

Achieving reliably high production of reactive oxygen species (ROS) in photodynamic therapy (PDT) remains challenging. Graphene quantum dots (GQDs) hold great promise for PDT. However, the photochemical processes leading to GQD-derived ROS generation have not yet been fully elucidated. Physicochemical characteristics of GQDs were comprehensively investigated, including electron paramagnetic resonance analysis of singlet oxygen production. Dark toxicity was assessed and . GQDs demonstrated excellent photoluminescent features, corrosion resistance, high water solubility, high photo/pH-stability, and biocompatibility and very efficient singlet oxygen/ROS generation. The enhanced ROS generation, combined with good biocompatibility and minimal toxicity and support the potential of GQDs for future PDT application.

A novel label-free surface plasmon resonance (SPR) aptasensor has been constructed for the detection of N-gene of SARS-CoV-2 by using thiol-modified niobium carbide MXene quantum dots (Nb 2 C-SH QDs) as the bioplatform for anchoring N-gene-targeted aptamer. In the presence of SARS-CoV-2 N-gene, the immobilized aptamer strands changed their conformation to specifically bind with N-gene. It thus increased the contact area or enlarged the distance between aptamer and the SPR chip, resulting in a change of the SPR signal irradiated by the laser (He-Ne) with the wavelength ( λ ) of 633 nm. Nb 2 C QDs were derived from Nb 2 C MXene nanosheets via a solvothermal method, followed by functionalization with octadecanethiol through a self-assembling method. Subsequently, the gold chip for SPR measurements was modified with Nb 2 C-SH QDs via covalent binding of the Au-S bond also by self-assembling interaction. Nb 2 C-SH QDs not only resulted in high bioaffinity toward aptamer but also enhanced the SPR response. Thus, the Nb 2 C-SH QD-based SPR aptasensor had low limit of detection (LOD) of 4.9 pg mL −1 toward N-gene within the concentration range 0.05 to 100 ng mL −1 . The sensor also showed excellent selectivity in the presence of various respiratory viruses and proteins in human serum and high stability. Moreover, the Nb 2 C-SH QD-based SPR aptasensor displayed a vast practical application for the qualitative analysis of N-gene from different samples, including seawater, seafood, and human serum. Thus, this work can provide a deep insight into the construction of the aptasensor for detecting SARS-CoV-2 in complex environments. Graphical abstract A novel label-free surface plasmon resonance aptasensor has been constructed to detect sensitively and selectively the N-gene of SARS-CoV-2 by using thiol-modified niobium carbide MXene quantum dots as the scaffold to anchor the N-gene-targeted aptamer.

Carbon dots (CDots) have emerged to represent a highly promising new platform for visible/natural light-activated microbicidal agents. In this article, the syntheses, structures, and properties of CDots are highlighted, representative studies on their activities against bacteria, fungi, and viruses reviewed, and the related mechanistic insights discussed. Also highlighted and discussed are the excellent opportunities for potentially extremely broad applications of this new platform, including theranostics uses.

The application of semiconductor nanocrystals containing cadmium, lead, selenium and mercury as constituent elements is strictly limited by concerns about environmental pollution and health effects. Nanocrystals free of these toxic elements are being pushed to the forefront of nanocrystal research because of their environmentally friendly advantages and attractive photophysical properties on recent advances in colloidal synthesis, excellent optical properties, optoelectronic device applications, and biological applications of these environmentally friendly fluorescent nanocrystals. In this context, the first topic in this review paper introduces group IV semiconductors. In particular, the unique light emitting properties generated in silicon nanocrystals of diameters smaller than bulk exciton Bohr radius are highlighted. Next the topic turns to the nanocrystals of group III–V semiconductors. After that, attentions are paid to the lead-free perovskite nanocrystals such as tin-based halide perovskite and double perovskite structures. Recent efforts on how to control nanostructures to enhance photoluminescence quantum yields is highlighted for each semiconductor nanocrystal. Finally, the remaining challenges that must be overcome to realize nontoxic optoelectronic devices will be discussed.

Carbon quantum dots (CQDs) are gaining a lot more attention than traditional semiconductor quantum dots owing to their intrinsic fluorescence property, chemical inertness, biocompatibility, non-toxicity, and simple and inexpensive synthetic route of preparation. These properties allow CQDs to be utilized for a broad range of applications in various fields of scientific research including biomedical sciences, particularly in bioimaging and biomedicines. CQDs are a promising choice for advanced nanomaterials research for bioimaging and biomedicines owing to their unique chemical, physical, and optical properties. CQDs doped with hetero atom, or polymer composite materials are extremely advantageous for biochemical, biological, and biomedical applications since they are easy to prepare, biocompatible, and have beneficial properties. This type of CQD is highly useful in phototherapy, gene therapy, medication delivery, and bioimaging. This review explores the applications of CQDs in bioimaging and biomedicine, highlighting recent advancements and future possibilities to increase interest in their numerous advantages for therapeutic applications.