Red-Emissive Carbon Quantum Dots for Nuclear Drug Delivery in Cancer Stem Cells

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Anti-Cancer Potency of Copper-Doped Carbon Quantum Dots Against Breast Cancer Progression

Introduction

The anti-cancer potency of copper-doped carbon quantum dots (Cu-CDs) against breast cancer progression needs more detailed investigations.

Methods

With urea and ethylene glycol applied as carbon sources and copper sulfate used as a reactive dopant, Cu-CDs were synthesized in the current study by a one-step hydrothermal synthesis method, followed by the characterization and biocompatibility evaluations of Cu-CDs. Subsequently, the anti-cancer potency of Cu-CDs against breast cancer progression was confirmed by these biochemical, molecular, and transcriptomic assessments, including viability, proliferation, migration, invasion, adhesion, clonogenicity, cell cycle distribution, apoptosis, redox homeostasis, and transcriptomic assays of MDA-MB-231 cells.

Results

The biocompatibility of Cu-CDs was confirmed based on the non-significant changes in the pathological and physiological parameters in the Cu-CDs treated mice, as well as the noncytotoxic effect of Cu-CDs on normal cells. Moreover, the Cu-CDs treatments not only decreased the viability, proliferation, migration, invasion, adhesion, and clonogenicity of MDA-MB-231 cells but also induced the redox imbalance, cell cycle arrest, and apoptosis of MDA-MB-231 cells via ameliorating the mitochondrial dysfunctions and regulating the MAPK signaling pathway.

Conclusion

Our findings confirmed the biosafety and excellent anti-cancer potency of Cu-CDs against breast cancer progression by tapping into mechanisms that disrupt malignant behaviors and oxidative homeostasis of breast cancer cells.

Highly Efficient Loading of Procaine on Water-Soluble Carbon Dots toward Long-Acting Anesthesia

Safe and efficient local anesthetic delivery carriers are crucial for long-term anesthesia and analgesics in clinical treatment. But currently, most of the local anesthetic carriers still have some disadvantages such as low drug-loading capacity, drug leakage, and potential side effects. Here, we report red-emissive carbon dots (Cys-CDs) synthesized by choosing cysteine and citric acid as precursors, which contain a large and intact sp2-domain with rich hydrophilic groups around the edge. The special structure of Cys-CDs is conducive to the efficient loading of procaine (PrC) via strong π-π stacking interactions. Based on the strong noncovalent interactions between them, the PrC loaded on Cys-CDs achieved slow release in vitro and had a long-lasting nerve blocking effect in vivo, which is 4-fold more than that of free PrC. More importantly, PrC/Cys-CDs do not cause any toxicity and inflammation during treatment owing to slow release of PrC and good water solubility of Cys-CDs, thus demonstrating the potential clinical application of CDs in long-lasting analgesia.

Paper-based microfluidic system and chiroptical functionalized gold nano-oval for colorimetric detection of L-Tryptophan

"The development and deployment of a practical and portable technology for on-site chiral identification of enantiomers hold immense significance in the fields of medical and biological sciences. Among the essential amino acids, Tryptophan (Trp) plays a crucial role in human metabolism and serves as a diagnostic marker for various metabolic disorders. In this study, we introduce an innovative approach that combines an enantio-selective ZIF-8-His MOF-MIPs packed-bed centrifugal microfluidic system with an enantioselective colorimetric sensor probe. This system is further integrated with smartphone-based on-site data recording. The basis of this colorimetric sensor's operation lies in the controlled morphology and surface passivation of gold nano-ovals (Au-NOs) through DL-Alanine. To confirm the successful synthesis of the chiral recognition elements, we employed various characterization techniques, including FE-SEM, TEM, FTIR, CD, UV-Vis, zeta potential, DLS, and XRD. Our focus was on optimizing operational parameters for the effective separation and determination of L-chiral tryptophan on-site. The sensor exhibited two linear ranges for L-Trp detection: 0-5.42 and 5.42-80.47 mM, with a detection limit of 0.5 mM. The integrated system possesses advantages such as ease of availability, preparation, high stability, desirable selectivity even in the presence of similar biomolecules, and rapid detection capabilities. Furthermore, our method demonstrated successful enantioselective sensing of L-Trp in various biological samples, including human blood plasma, urine, milk, and bovine serum albumin (BSA), yielding promising results. The integrated microfluidic platform follows a "sample-in and answer-out" approach, making it highly applicable in healthcare, environmental monitoring, food safety analysis, and point-of-care testing. The chiral recognition pretreatment assay and self-contained, automated colorimetric detection on the microfluidic disc represent a promising avenue for cutting-edge research in these domains".

Dacarbazine-primed carbon quantum dots coated with breast cancer cell-derived exosomes for improved breast cancer therapy

Imprecise targeting of chemotherapeutic drugs often leads to severe toxicity during breast cancer therapy. To address this issue, we have devised a strategy to load dacarbazine (DC) into fucose-based carbon quantum dots (CQDs), which are subsequently coated with exosomes (Ex-DC@CQDs) derived from breast cancer cells. Nanoparticle tracking analysis and western blotting revealed that Ex-DC@CQDs retained the structural and functional characteristics of exosomes. We found that exosomes facilitated the transport of DC@CQDs to cancer cells via heparan sulfate proteoglycan (HSPG) receptors, followed by an augmented depolarization of the mitochondrial membrane potential, ROS generation, and induction of apoptosis leading to cell death. In vivo imaging and pharmacokinetic studies demonstrated enhanced antitumor targeting and efficacy compared to free DC which we attribute to an improved pharmacokinetic profile, a greater tumor accumulation via exosome-mediated- HSPG receptor-driven cell uptake, and sustained release of the Ex-DC@CQDs. Our findings may pave the way for the further development of biologically sourced nanocarriers for breast cancer targeting.

Revolutionizing Cancer Care: Advances in Carbon-Based Materials for Diagnosis and Treatment

Cancer involves intricate pathological mechanisms marked by complexities such as cytotoxicity, drug resistance, stem cell proliferation, and inadequate specificity in current chemotherapy approaches. Cancer therapy has embraced diverse nanomaterials renowned for their unique magnetic, electrical, and optical properties to address these challenges. Despite the expanding corpus of knowledge in this area, there has been less advancement in approving nano drugs for use in clinical settings. Nanotechnology, and more especially the development of intelligent nanomaterials, has had a profound impact on cancer research and treatment in recent years. Due to their large surface area, nanoparticles can adeptly encapsulate diverse compounds. Furthermore, the modification of nanoparticles is achievable through a broad spectrum of bio-based substrates, including DNA, aptamers, RNA, and antibodies. This functionalization substantially enhances their theranostic capabilities. Nanomaterials originating from biological sources outperform their conventionally created counterparts, offering advantages such as reduced toxicity, lower manufacturing costs, and enhanced efficiency. This review uses carbon nanomaterials, including graphene-based materials, carbon nanotubes (CNTs) based nanomaterials, and carbon quantum dots (CQDs), to give a complete overview of various methods used in cancer theranostics. We also discussed their advantages and limitations in cancer diagnosis and treatment settings. Carbon nanomaterials might significantly improve cancer theranostics and pave the way for fresh tumor diagnosis and treatment approaches. More study is needed to determine whether using nano-carriers for targeted medicine delivery may increase material utilization. More insight is required to explore the correlation between heightened cytotoxicity and retention resulting from increased permeability.

Carbon dot/Co-MOF nanocoral mediated fluorescence-scattering ratiometric sensor for highly sensitive detection of alkaline phosphatase

Abnormal expression of alkaline phosphatase (ALP) in serum has received considerable attention in health monitoring and disease diagnosis. However, conventional optical analysis based on a single signal must compromise background interference and limited sensitivity in trace analysis. As an alternative candidate, the ratiometric approach depends on the self-calibration of two independent signals in a single test to minimize interferences from the background for accurate identification. Here, a carbon dot/cobalt-metal organic framework nanocoral (CD/Co-MOF NC) mediated fluorescence-scattering ratiometric sensor has been developed for simple, stable, and highly sensitive detection of ALP. ALP-responsive phosphate production was used to coordinate cobalt ion and collapse the CD/Co-MOF NC, resulting in the recovery of fluorescence signal from dissociative CDs and the decrease of second-order scattering (SOS) signal from the cracked CD/Co-MOF NC. The ligand-substituted reaction and the optical ratiometric signal transduction provide a rapid and reliable chemical sensing mechanism. The ratiometric sensor effectively converted ALP into a ratio signal of fluorescence-scattering dual emission throughout a wide linear concentration range of six orders of magnitude with a detection limit of 0.6 mU/L. In addition, self-calibration of fluorescence-scattering ratiometric method can reduce background interference and improve sensitivity in serum, approaching recoveries of ALP from 98.4% to 101.8%. Due to the above advantages, the CD/Co-MOF NC mediated fluorescence-scattering ratiometric sensor readily provides rapid and stable quantitative detection of ALP as a promising in vitro analytical method for clinical diagnostics.

Molecular targets, therapeutic agents and multitasking nanoparticles to deal with cancer stem cells: A narrative review

There is increasing evidence that malignant tumors are initiated and maintained by a sub-population of tumor cells that have similar biological properties to normal adult stem cells. This very small population of Cancer Stem Cells (CSC) comprises tumor initiating cells responsible for cancer recurrence, drug resistance and metastasis. Conventional treatments such as chemotherapy, radiotherapy and surgery, in addition to being potentially toxic and non-specific, may paradoxically increase the population, spread and survival of CSCs. Next-generation sequencing and omics technologies are increasing our understanding of the pathways and factors involved in the development of CSCs, and can help to discover new therapeutic targets against CSCs. In addition, recent advances in nanomedicine have provided hope for the development of optimal specific therapies to eradicate CSCs. Moreover, the use of artificial intelligence and nano-informatics can elucidate new drug targets, and help to design drugs and nanoparticles (NPs) to deal with CSCs. In this review, we first summarize the properties of CSCs and describe the signaling pathways and molecular characteristics responsible for the emergence and survival of CSCs. Also, the location of CSCs within the tumor and the effect of host factors on the creation and maintenance of CSCs are discussed. Newly discovered molecular targets involved in cancer stemness and some novel therapeutic compounds to combat CSCs are highlighted. The optimum properties of anti-CSC NPs, including blood circulation and stability, tumor accumulation and penetration, cellular internalization, drug release, endosomal escape, and aptamers designed for specific targeting of CSCs are covered. Finally, some recent smart NPs designed for therapeutic and theranostic purposes to overcome CSCs are discussed.

Carbon Dots for Electroluminescent Light-Emitting Diodes: Recent Progress and Future Prospects

Carbon dots (CDs), as emerging carbon nanomaterials, have been regarded as promising alternatives for electroluminescent light-emitting diodes (LEDs) owing to their distinct characteristics, such as low toxicity, tuneable photoluminescence, and good photostability. In the last few years, despite remarkable progress achieved in CD-based LEDs, their device performance is still inferior to that of well-developed organic, heavy-metal-based QDs, and perovskite LEDs. To better exploit LED applications and boost device performance, in this review, a comprehensive overview of currently explored CDs is presented, focusing on their key optical characteristics, which are closely related to the structural design of CDs from their carbon core to surface modifications, and to macroscopic structural engineering, including the embedding of CDs in the matrix or spatial arrangement of CDs. The design of CD-based LEDs for display and lighting applications based on the fluorescence, phosphorescence, and delayed fluorescence emission of CDs is also highlighted. Finally, it is concluded with a discussion regarding the key challenges and plausible prospects in this field. It is hoped that this review inspires more extensive research on CDs from a new perspective and promotes practical applications of CD-based LEDs in multiple directions of current and future research.

Comprehensive advances in the synthesis, fluorescence mechanism and multifunctional applications of red-emitting carbon nanomaterials

Red emitting fluorescent carbon nanomaterials have drawn significant scientific interest in recent years due to their high quantum yield, water-dispersibility, photostability, biocompatibility, ease of surface functionalization, low cost and eco-friendliness. The red emissive characteristics of fluorescent carbon nanomaterials generally depend on the carbon source, reaction time, synthetic approach/methodology, surface functional groups, average size, and other reaction environments, which directly or indirectly help to achieve red emission. The importance of several factors to achieve red fluorescent carbon nanomaterials is highlighted in this review. Numerous plausible theories have been explained in detail to understand the origin of red fluorescence and tunable emission in these carbon-based nanostructures. The above advantages and fluorescence in the red region make them a potential candidate for multifunctional applications in various current fields. Therefore, this review focused on the recent advances in the synthesis approach, mechanism of fluorescence, and electronic and optical properties of red-emitting fluorescent carbon nanomaterials. This review also explains the several innovative applications of red-emitting fluorescent carbon nanomaterials such as biomedicine, light-emitting devices, sensing, photocatalysis, energy, anticounterfeiting, fluorescent silk, artificial photosynthesis, etc. It is hoped that by choosing appropriate methods, the present review can inspire and guide future research on the design of red emissive fluorescent carbon nanomaterials for potential advancements in multifunctional applications.

Protein Delivery to the Cytosol and Cell Nucleus via Micellar Nanocarrier-Based Nonendocytic Uptake

Although efficient cell nucleus delivery of exogenous materials can greatly improve their biochemical activity, this is strictly restricted by cellular uptake and intracellular trafficking processes. In the current approach, synthetic carriers are designed for cell delivery of exogenous materials via endocytosis, and nucleus delivery can be achieved via endosomal escape. Here, we demonstrate that a nonendocytic cell uptake approach can be adapted for protein delivery to the cell nucleus. We have designed a phenylboronic acid-terminated micellar carrier that can bind with protein in the presence of green tea polyphenol and deliver protein into the cytosol via the nonendocytic approach. Using this approach, four different proteins are delivered to the cytosol within 15 min, and low-molecular weight proteins are delivered to the nucleus. The designed approach can be extended for delivering macromolecular drugs to subcellular targets for a more efficient therapy.

A promising tool for clinical diagnostics: Dual-emissive carbonized polymer dots based cross-linking enhanced emission for sensitive detection of alkaline phosphatase and butyrylcholinesterase

Compared with single signal readout, dual-signal readout commendably corrects the impact of systematic or background error, achieving more accurate results for the diagnosis of many diseases. This work aimed to design and prepare dual-emissive fluorescent probes for the construction of ratiometric fluorescence biosensors to detect liver disease biomarkers. Sodium alginate (SA) with numerous potential sub-fluorophores and active sites and 4,4',4'',4'''-(porphine-5,10,15,20-tetrayl) tetrakis (benzoic acid) (TCPP) with macrocyclic conjugated structures were introduced to prepare the carbonized polymer dots (CPDs) with red/blue dual emission based on the cross-linking enhanced emission (CEE) effect and the luminescence of macrocyclic conjugated structures. The ratiometric fluorescence sensing systems were constructed by integrating the specific response of CPDs to Cu2+ and the affinity difference of Cu2+ to substrates or products of enzymes. The sensing systems, CPDs/Cu2+/PPi and CPDs/Cu2+/BTCh, were designed to detect liver disease biomarkers, alkaline phosphatase (ALP) and butyrylcholinesterase (BChE), respectively. The limit of detection for ALP and BChE was 0.35 U/L and 0.19 U/L, respectively. The proposed sensors were successfully applied to human serum samples from different health stages with satisfactory recoveries. These results demonstrate the successful design of a novel dual-emissive fluorescent probe and provide a feasible strategy for clinical detection.

Luminescence of carbon quantum dots and their application in biochemistry

Similar to fullerenes, carbon nanotubes and graphene, carbon dots (CDs) are causing a lot of research work in their own right. CDs are a type of surface-passivated quantum dot that contain carbon atoms. Their distinctive characteristics, such as luminescent emission that varies with size and wavelength, resistance to photobleaching, easy biological binding, lack of toxicity, and economical production without the need for intricate synthetic processes, have led to a noteworthy surge in attention within the research community. Different techniques can be utilized to create these CDs, spanning from basic candle burning to laser ablation. This review article delves into the principles of fluorescence technology, providing insights into how different synthesis methods of quantum dots impact their luminescent properties. Additionally, it highlights the latest applications of quantum dots in catalysis and biomedical fields, with special emphasis on the current status of luminescent properties in biology and chemistry. Towards the end, the article discusses the limitations of quantum dots in current practical applications, pointing out that CDs hold promising potential for future applications.

Red emissive carbon dots: a promising next-generation material with intracellular applicability

The accidental discovery of carbon dots (CDs) back in 2004 has led to their widespread use in the biomedical field. CDs have demonstrated their effectiveness in reporting 3D structures of biological specimens, identifying normal and cancer cells, and even detecting analytes within cells. However, the limitations of blue-green emitting CDs, such as their shallow penetration, photodamage, and auto-fluorescence, have hindered their practical applications. To overcome these limitations, red emissive CDs (RCDs) have been developed, which have deep tissue penetration, minimal photo-damage, low auto-fluorescence, and high imaging contrast. In this article, we present a thorough review on the use of RCDs in biomedical applications, including in vivo and in vitro bioimaging, photoacoustic imaging, monitoring temperature and polarity changes in living cells, tumour therapy, and drug delivery. With the rapid progress being made in the development of RCDs for intracellular applications, their clinical application is expected to become a reality in the near future.

Recent Breakthroughs in Using Quantum Dots for Cancer Imaging and Drug Delivery Purposes

Cancer is one of the leading causes of death worldwide. Because each person's cancer may be unique, diagnosing and treating cancer is challenging. Advances in nanomedicine have made it possible to detect tumors and quickly investigate tumor cells at a cellular level in contrast to prior diagnostic techniques. Quantum dots (QDs) are functional nanoparticles reported to be useful for diagnosis. QDs are semiconducting tiny nanocrystals, 2-10 nm in diameter, with exceptional and useful optoelectronic properties that can be tailored to sensitively report on their environment. This review highlights these exceptional semiconducting QDs and their properties and synthesis methods when used in cancer diagnostics. The conjugation of reporting or binding molecules to the QD surface is discussed. This review summarizes the most recent advances in using QDs for in vitro imaging, in vivo imaging, and targeted drug delivery platforms in cancer applications.

One-Pot Synthesis of Dual-Emissive Carbon Dots for Ratiometric Fluorescent Determination of Hg2

Mercury ion is a global toxic and hazardous environmental pollutant. In this work, a facile and selective ratiometric fluorescent probe was constructed for the detection of mercury ion. The dual-emissive carbon dots (BYCDs) were fabricated by a one-pot hydrothermal method utilizing o-phenylenediamine and glycine as raw materials, and the prepared BYCDs had two independent fluorescence emission peaks at 426 nm and 543 nm under a single excitation wavelength. Based on the change of the intensity ratio of the two fluorescence emission peaks after the addition of Hg2+, a sensitive and selective ratiometric fluorescent probe based on BYCDs was constructed for the detection of Hg2+ with good linearity ranging from 0.95-50 μM and a detection limit of 0.27 μM. In addition, the recovery of this probe was satisfactory in the standard addition experiments of real water samples, and it could be applied to the analysis of Hg2+ in real water samples.

Red emitting carbon dots: surface modifications and bioapplications

Quantum dots (QDs), and carbon quantum dots (CDs) in particular, have received significant attention for their special characteristics. These particles, on the scale of several nanometers, are often produced using simple and green methods, with naturally occurring organic precursors. In addition to facile production methods, CDs present advantageous applications in the field of medicine, primarily for bioimaging, antibacterial and therapeutics. Also, CDs present great potential for surface modification through methods like doping or material mixing during synthesis. However, the bulk of current literature focuses on CDs emitting in the blue wavelengths which are not very suitable for biological applications. Red emitting CDs are therefore of additional interest due to their brightness, photostability, novelty and deeper tissue penetration. In this review article, red CDs, their methods of production, and their biological applications for translational research are explored in depth, with emphasis on the effects of surface modifications and doping.

Synthesis, properties and potential applications of photoluminescent carbon nanoparticles: A review

Photoluminescent-carbon nanoparticles (PL-CNPs) are a new class of materials that received immense interest among researchers due to their distinct characteristics, including photoluminescence, high surface-to-volume ratio, low cost, ease of synthesis, high quantum yield, and biocompatibility. By exploiting these outstanding properties, many studies have been reported on its utility as sensors, photocatalysts, probes for bio-imaging, and optoelectronics applications. From clinical applications to point-of-care test devices, drug loading to tracking of drug delivery, and other research innovations demonstrated PL-CNPs as an emerging material that could substitute conventional approaches. However, some of the PL-CNPs have poor PL properties and selectivity due to the presence of impurities (e.g., molecular fluorophores) and unfavourable surface charges by the passivation molecules, which impede their applications in many fields. To address these issues, many researchers have been paying great attention to developing new PL-CNPs with different composite combinations to achieve high PL properties and selectivity. Herein, we thoroughly discussed the recent development of various synthetic strategies employed to prepare PL-CNPs, doping effects, photostability, biocompatibility, and applications in sensing, bioimaging, and drug delivery fields. Moreover, the review discussed the limitations, future direction, and perspectives of PL-CNPs in possible potential applications.

Progress in drug delivery and diagnostic applications of carbon dots: a systematic review

Carbon dots (CDs), which have particle size of less than 10 nm, are carbon-based nanomaterials that are used in a wide range of applications in the area of novel drug delivery in cancer, ocular diseases, infectious diseases, and brain disorders. CDs are biocompatible, eco-friendly, easy to synthesize, and less toxic with excellent chemical inertness, which makes them very good nanocarrier system to deliver multi-functional drugs effectively. A huge number of researchers worldwide are working on CDs-based drug delivery systems to evaluate their versatility and efficacy in the field of pharmaceuticals. As a result, there is a tremendous increase in our understanding of the physicochemical properties, diagnostic and drug delivery aspects of CDs, which consequently has led us to design and develop CDs-based theranostic system for the treatment of multiple disorders. In this review, we aim to summarize the advances in application of CDs as nanocarrier including gene delivery, vaccine delivery and antiviral delivery, that has been carried out in the last 5 years.

Perspectives of different colour-emissive nanomaterials in fluorescent ink, LEDs, cell imaging, and sensing of various analytes

In the past 2 decades, multicolour light-emissive nanomaterials have gained significant interest in chemical and biological sciences because of their unique optical properties. These materials have drawn much attention due to their unique characteristics towards various application fields. The development of novel nanomaterials has become the pinpoint for different application areas. In this review, the recent progress in the area of multicolour-emissive nanomaterials is summarized. The different emissions (white, orange, green, red, blue, and multicolour) of nanostructure materials (metal nanoclusters, quantum dots, carbon dots, and rare earth-based nanomaterials) are briefly discussed. The potential applications of different colour-emissive nanomaterials in the development of fluorescent inks, light-emitting diodes, cell imaging, and sensing devices are briefly summarized. Finally, the future perspectives of multicolour-emissive nanomaterials are discussed.

Design of carbon dots for bioimaging and behavior regulation of stem cells

Carbon dots (CDs) have been widely used in bioimaging, biosensing and biotherapy because of their good biocompatibility, optical properties and stability. In this review, we comprehensively summarize the research on CDs in terms of synthesis methods, optical properties and biotoxicity. We describe and envisage the directions for CDs application in stem cell imaging and differentiation, with the aim of stimulating the design of future related CDs. We used 'carbon dots', 'stem cells', 'cell imaging', 'cell differentiation' and 'fate control' as keywords to search for important articles. The Web of Science database was used to extract vital information from a total of 357 papers, 126 review articles and 231 article proceedings within 12 years (2011-2022).

Red-emissive carbon nanostructure-anchored molecularly imprinted Er-BTC MOF: a biosensor for visual anthrax monitoring

Investigating effective fluorescence strategies for real-time monitoring of dipicolinic acid (DPA) is of paramount importance in safeguarding human health. Herein, we present the design of a desirable red-emissive carbon nanostructure anchoring a molecularly imprinted Er-BTC MOF as a fluorescence biosensor for the visual determination of DPA. DPA is a biomarker of Bacillus anthracis, a subcategory of serious infectious diseases and bioweapons. We introduce a paper test strip sensitized with the aforementioned nanostructure, which is integrated with online UV excitation and smartphone digital imaging, resulting in a DPA signal-off sensing platform. The proposed fluorometric visual paper-based biosensor demonstrates wide linear ranges for DPA (10-125 μM) with a LOQ and LOD of 4.32 and 1.28 μM, respectively. The designed platform exhibits impressive emission properties and adaptable surface functional groups, which confirm its desirable selective sensing capabilities against other biological molecules and DPA isomers. As a proof of concept, DPA monitoring is successfully applied to real samples of tap water and urine. This integrated selective paper-based nano-biosensor, coupled with smartphone signal recording, holds great promise for state-of-the-art practical applications including fluorometric/colorimetric detection in healthcare and environmental monitoring, food safety analysis, and point-of-care testing.

Cancer cells inhibition by cationic carbon dots targeting the cellular nucleus

Nucleus targeting is tremendously important in cancer therapy. Cationic carbon dots (CCDs) are potential nanoparticles which might enter cells and penetrate nuclear membranes. Although some CCDs have been investigated in nucleus targeting and applied in nuclear imaging, the CCDs derived from drugs, that are able to target the nucleus, bind with DNA and inhibit the growth of cancer cells have not been reported. In this project, 1, 2, 4, 5-benzenetetramine (Y15, a focal adhesion kinase inhibitor) derived cationic carbon dots (Y15-CDs) were prepared via a hydrothermal approach utilizing Y15, folic acid and 1,2-ethylenediamine as precursors. Based on the structural, optical, and morphologic characterizations, Y15-CDs possess rich amine groups and nitrogen in structure, an excitation-dependent photoluminescence emission, and a small particle size of 2 to 4 nm. The DNA binding experiments conducted through agarose gel electrophoresis, UV-vis absorption, fluorescence emission, and circular dichroism spectroscopies, prove that Y15-CDs might bind with DNA via electrostatic interactions and partially intercalative binding modes. In addition, the cell imaging and cytotoxicity studies in human foreskin fibroblasts (HFF), prostate cancer (PC3) and osteosarcoma cells (U2OS) indicate the nucleus targeting and anticancer abilities of Y15-CDs. Most interestingly, Y15-CDs exhibit a higher cytotoxicity to cancer cells (PC3 and U2OS) than to normal cells (HFF), inferring that Y15-CDs might be potentially applied in cancer therapy.

Fluorescence Signal Amplification: Red Carbon Dots@SiO2-Induced Ultra-sensitive Immunoassay for Diethyl Phthalate

Carbon dots as new nanomaterials, have been widely used in rapid detection because of their nondestructive, real-time detection characteristics. Improving the sensitivity and selectivity of the method in complex real samples is new challenge and requirement for sensing technology. Here, we report an ultrasensitive fluorescence immunoassay (FIA) for trace diethyl phthalate (DEP) using red carbon dots@SiO₂ (R-CDs@SiO₂) as tags. SiO₂ as a nanocarrier can effectively improve the bio-functionalization and utilization rate of carbon dots. Moreover, several R-CDs embedded in SiO₂ nanospheres can magnify the fluorescence signal and improve sensitivity. R-CDs@SiO₂ conjugate anti-DEP antibody (Ab) as fluorescent immunosensor, which can specifically recognize DEP. Under optimization conditions, the detection limit (LOD) of this FIA was calculated as 0.0011 ng/mL. In addition, the recoveries of this established FIA ranged from 96.8 to 108.5%, showing satisfactory accuracy. Compared with GC-MS/MS (LOD µg/mL), the sensitivity of the FIA was significantly improved. As a result, the FIA developed using R-CDs@SiO₂ as tags has a high potential for determining trace DEP.

In Vivo and In Vitro Biodistribution of Inulin-Tethered Boron-Doped Amine-Functionalized Carbon Dots

Carbon dots (CDs) are considered a potential substance for use in biomarker applications due to their exceptional light stability. However, there are several unsolved uncertainties about CD toxicity in vitro and in vivo. In this study, a redesigned derivative of the natural polysaccharide inulin is connected with boron-doped amine-functionalized carbon dots (In@BN-CDs) through carbodiimide coupling to improve the biocompatibility of the nanoformulation. The toxicity and biodistribution of ln@BN-CDs in vivo and in vitro were explored in detail. The In@BN-CDs were tested after a single inhalation dosage of 10, 7, 5, 3, and 1 mg/kg. We explored a dose- and time-dependent technique of collecting blood samples and then centrifuged the blood samples and obtained serum samples, which were then analyzed for fluorescence inspection; findings showed that the fluorescence intensity decreased with time. Similarly, In@BN-CDs were effectively used as in vitro toxicity and fluorescent probes for cellular imaging in living cells due to their biocompatibility and cell membrane accessibility. The biocompatibility and efficacy of In@BN-CDs as fluorescent imaging agents have been demonstrated. The data suggest that the usage of In@BN-CDs in vitro and in vivo should be examined.

Rational Design of Nitrogen-Doped Carbon Dots for Inhibiting β-Amyloid Aggregation

The fibrillization and abnormal aggregation of β-amyloid (Aβ) peptides are commonly recognized risk factors for Alzheimer's disease (AD) brain, and require an effective strategy to inhibit the Aβ deposition and treat AD. Herein, we designed and synthesized nitrogen-doped carbon dots (N-CDs) as an Aβ-targeted probe, which exhibits the capacity of inhibiting the 1-42 Aβ (Aβ1-42) self-assembly in vitro. The N-CDs exhibited orange emission with an emission wavelength of 570 nm, which demonstrates their excellent optical properties with excitation-independent behavior. Meanwhile, the N-CDs have spherical morphologies with an average size of 2.2 nm, whose surface enriches the amino, carboxyl, and hydroxyl groups. These preparties are conducive to improving their biological water solubility and provide a large number of chemical bonds for further interaction with proteins. Contrary to this, the kinetic process, size evolutions, and morphologies changes of Aβ1-42 were inhibited in the presence of N-CDs in the determination of a thioflavin T assay, dynamic light scattering, transmission electron microscope, etc. Finally, the safety application of N-CDs on Aβ1-42-induced cytotoxicity was further demonstrated via in vitro cytotoxicity experiments. This work demonstrates the effective outcome of suppressing Aβ aggregation, which provides a new view into the high-efficiency and low-cytotoxicity strategy in AD theranostics.

The Formation Process and Mechanism of Carbon Dots Prepared from Aromatic Compounds as Precursors: A Review

Fluorescent carbon dots are a novel type of nanomaterial. Due to their excellent optical properties, they have extensive application prospects in many fields. Studying the formation process and fluorescence mechanism of CDs will assist scientists in understanding the synthesis of CDs and guide more profound applications. Due to their conjugated structures, aromatic compounds have been continuously used to synthesize CDs, with emissions ranging from blue to NIR. There is a lack of a systematic summary of the formation process and fluorescence mechanism of aromatic precursors to form CDs. In this review, the formation process of CDs is first categorized into three main classes according to the precursor types of aromatic compounds: amines, phenols, and polycyclics. And then, the fluorescence mechanism of CDs synthesized from aromatic compounds is summarized. The challenges and prospects are proposed in the last section.

Enhancing the photoluminescence and cellular uptake of fluorescent carbon nanodots via cubosome lipid nanocarriers

Carbon nanodots (C-dots) have attracted much attention for their use in the fields of bioimaging, drug delivery, and sensing due to their excellent fluorescent and photoluminescent properties, photostability, biocompatibility, and amenability to surface modification. Herein, we report a nanocomposite formulation of C-dots (<5 nm) encapsulated in lipid-based lyotropic liquid crystalline nanoparticles (∼250 nm) via either passive diffusion or electrostatic mechanisms. The physicochemical properties of the nanocomposite formulation including particle size, surface charge, internal cubic nanostructures, and pH-dependent fluorescent properties were characterised. Upon loading of C-dots into lipid nanoparticles, the highly ordered inverse bicontinuous cubic mesophase existed in the internal phase of the nanoparticles, demonstrated by synchrotron small angle X-ray scattering, molecular dynamic simulation and cryogenic transmission electron microscopy. The pH-dependent fluorescent property of the C-dots was modified via electrostatic interaction between the C-dots and cationic lipid nanoparticles, which further enhanced the brightness of C-dots through self-quenching prevention. The cytotoxicity and cellular uptake efficiency of the developed nanocomposites were also examined in an epithelial gastric adenocarcinoma cell line (AGS) and a macrophage cell line (stimulated THP-1). Compared to free C-dots, the uptake and cell imaging potential of the C-dot nanocomposites was significantly improved, by several orders of magnitude as demonstrated by cytoplasmic fluorescent intensities using confocal microscopy. Loading C-dots into mesoporous lipid nanocarriers presents a new way of modifying C-dot physicochemical and fluorescent properties, alternative to direct chemical surface modification, and advances the bioimaging potential of C-dots by enhancing cellular uptake efficiency and converging C-dot light emission.

Carbon-based nanostructures for cancer therapy and drug delivery applications

Synthesis, design, characterization, and application of carbon-based nanostructures (CBNSs) as drug carriers have attracted a great deal of interest over the past half of the century because of their promising chemical, thermal, physical, optical, mechanical, and electrical properties and their structural diversity. CBNSs are well-known in drug delivery applications due to their unique features such as easy cellular uptake, high drug loading ability, and thermal ablation. CBNSs, including carbon nanotubes, fullerenes, nanodiamond, graphene, and carbon quantum dots have been quite broadly examined for drug delivery systems. This review not only summarizes the most recent studies on developing carbon-based nanostructures for drug delivery (e.g. delivery carrier, cancer therapy and bioimaging), but also tries to deal with the challenges and opportunities resulting from the expansion in use of these materials in the realm of drug delivery. This class of nanomaterials requires advanced techniques for synthesis and surface modifications, yet a lot of critical questions such as their toxicity, biodistribution, pharmacokinetics, and fate of CBNSs in biological systems must be answered.

Synthesis of Hollow Calcium Carbonate Microspheres by a Template Method for DOX Loading and Release with Carbon Dots Photosensitivity

Calcium carbonate, as the main inorganic component of human bones and teeth, has good biocompatibility and bioactivity and finds increasing applications in the field of bone drug carriers. In this study, hollow calcium carbonate microspheres were synthesized by a water hydrothermal method using folic acid as a template. Before drug loading, the prepared calcium carbonate microspheres were subjected to aminidation, carboxylation, and vinylenimine modification. The hollow calcium carbonate microspheres loaded with doxorubicin hydrochloride (DOX) were further incorporated with light-emitting carbon quantum dots(CQDs) and hyaluronic acid (HA). The result showed that the drug loading capacity in the as-prepared calcium carbonate was 179.064 mg/g. In the simulated solutions of cellular metabolism containing various concentrations of reduced glutathione(GSH), the sustained release of DOX was confirmed qualitatively by the luminescence of the CQDs. The DOX release rate was measured quantitively by UV absorption spectra. The highest release rate reached 85.99% in a simulated solution of 0.005 mol/L GSH solution, and the release rate could vary intelligently with the concentration.

Nuclear-targeted carbon quantum dot mediated CRISPR/Cas9 delivery for fluorescence visualization and efficient editing

Nuclear targeted delivery has great potential in improving the efficiency of non-viral carrier mediated genome editing. However, direct and efficient delivery of CRISPR/Cas9 plasmid into the nucleus remains a challenge. In this study, a nuclear targeted gene delivery platform based on fluorescent carbon quantum dots (CQDs) was developed. Polyethylenimine (PEI) and polyethylene glycol (PEG) synergistically passivated the surface of CQDs, providing an excitation-independent green-emitting fluorescent CQDs-PEI-PEG conjugate (CQDs-PP) with an ultra-small size and positive surface charge. Here we show that CQDs-PP could bind CRISPR/Cas9 plasmid to form a nano-complex by electrostatic attraction, which can bypass lysosomes and enter the nucleus by passive diffusion, and thereby improve the transfection efficiency. Also, CQDs-PP could deliver CRISPR/Cas9 plasmid into HeLa cells, resulting in the insertion/deletion mutation of the target EFHD1 gene. More importantly, CQDs-PP exhibited a considerably higher gene editing efficiency as well as comparable or lower cytotoxicity relative to Lipo2000 and PEI-passivated CQDs-PEI (CQDs-P). Thus, the nuclear-targeted CQDs-PP is expected to constitute an efficient CRISPR/Cas9 delivery carrier in vitro with imaging-trackable ability.

One step synthesis of ultra-high quantum yield fluorescent carbon dots for "on-off-on" detection of Hg2+ and biothiols

In this paper, the carbon dots (CDs) with strong blue fluorescence were synthesized through hydrothermal method, which using folic acid, ammonium citrate and ethylenediamine as precursors. The prepared CDs with a high absolute quantum yield of 81.94% and showed excellent stability in high concentration salt solution and different pH conditions. With the addition of Hg²⁺, the signal of CDs was selectively quenched. At the same time, the CDs-Hg²⁺ system could be recovered after the introduction of biothiols. Moreover, the fluorescence of CDs showed a good linear relationship with Hg²⁺ (1-15 µM), and the detection limit as low as 0.08 µM. In addition, the prepared CDs with low toxicity could be used to detect Hg²⁺ in living cells and actual water samples.

Carbon Quantum Dots for Stem Cell Imaging and Deciding the Fate of Stem Cell Differentiation

Nanotechnology advancements and applications have paved the way for new possibilities in regenerative medicine and tissue engineering. It is a relatively new field that has the potential to improve stem cell differentiation and therapy greatly. Numerous studies have demonstrated that nanomaterials can function as a physiological niche for the formation and differentiation of stem cells. However, quantum dots (QDs), such as carbon quantum dots (CQDs) and graphene quantum dots (GQDs), have shown considerable promise in the field of regenerative medicine. To date, most research has focused on stem cell tracking and imaging using CQDs. However, their interaction with stem cells and the associated possibility for differentiation by selectively focusing chemical signals to a particular lineage has received scant attention. In this mini-review, we attempt to categorize a few pathways linked with the role of CQDs in stem cell differentiation.

In vitro effects of combustion generated carbon dots on cellular parameters in healthy and cancerous breast cells

Carbon nanomaterials are an inventive class of materials with wide applications in state-of-the-art bioimaging and therapeutics. They allow a broad range of tunable and integrated advantages of structural flexibility, chemical and thermal stability, upright electrical conductivity, and the option of scale-up and mass production. In the context of nanomedicine, carbon nanomaterials have been used extensively to mitigate the serious side effects of conventional chemotherapy and also to enable early cancer diagnostics, given their wide range of tunable properties. A class of carbon nanomaterials, called carbon dots (CDs) are small carbon-based nanoparticles and have been a valued discovery due to their photoluminescence, low photobleaching, and high surface area to mass ratio. The process of producing these CDs had so far been a high energy demanding process involving wet chemistry for purification. A one-step tunable production of luminescent CDs from fuel rich combustion reactors was recently presented by our group. In this paper, we explore the effects of these yellow luminescent combustion-generated CDs in MCF7 adenocarcinoma and MCF10a normal breast epithelial cells. We observed that these CDs, also at nontoxic doses, can affect basic cellular functions, such as cell cycle and proliferation; induce substantial changes on the physical parameters of the plasma membrane; and change the overall appearance of a cell in terms of morphology.

Folic Acid-Modified Cerium-Doped Carbon Dots as Photoluminescence Sensors for Cancer Cells Identification and Fe(III) Detection

Carbon dots (CDs) are a new class of carbon-based luminescence materials with fascinating properties. They have been given great expectations on superseding traditional semiconductor quantum dots due to their good dispersity and stability, relatively low toxicity, superior resistance to photobleaching, and excellent biocompatibility. The diversified luminescence properties of CDs are largely due to the synthetic strategies and precursors. In view of those described above, this study has explored the possibility to establish a facile one-step hydrothermal method for the one-pot synthesis of folic acid-modified cerium-doped CDs (Ce-CDs-FA), which could be further utilized as a sensitive fluorescent nanoprobe for biosensing. This investigation demonstrates that the Ce-CDs-FA nanocomposites have nice biocompatibility and bright fluorescent properties, which can be readily utilized to detect cancer cells through recognizing overexpressing folate receptors by virtue of folic acid. Meanwhile, it is noted that the Fe3+ ion can actualize a specific and hypersensitive quenching effect for these Ce-CDs-FA nanocomposites, which can be further explored for special ion recognition, including iron ions. It raises the possibility that the as-prepared Ce-CDs-FA nanocomposites could be extended as a dual fluorescence sensor for targeted cell imaging and Fe3+ ion detection.

Highly Luminescent Nucleoside-Based N, P-Doped Carbon Dots for Sensitive Detection of Ions and Bioimaging

The efficient detection of Fe3+ and MnO4− in a water environment is very important and challenging due to their harmful effects on the health of humanity and environmental systems. Good biocompatibility, sensitivity, selectivity, and superior photophysical properties were important attributes of carbon dot-based CDs sensors for sensing applications. In this work, we synthesized N, P-co-doped carbon dots (N/P CDs) with guanosine 5′-monophosphate (GMP) as a green carbon source, with high fluorescence quantum yield in water (QY, 53.72%). First, the luminescent N/P CDs showed a three-state “on-off-on” fluorescence response upon the sequential addition of Fe3+ and F−, with a low detection limit of 12 nM for Fe3+ and 8.5 nM for F−, respectively. Second, the N/P CDs also exhibited desirable selectivity and sensitivity for toxic MnO4− detection with the limit of detection of 18.2 nM, through a turn-off mechanism. Moreover, the luminescent N/P CDs successfully monitored the aforementioned ions in environmental water samples and in Escherichia coli.

Pressure-Induced Bifurcation in the Photoluminescence of Red Carbon Quantum Dots: Coexistence of Emissions from Surface Groups and Nitrogen-Doped Cores

Carbon quantum dots (CDs) with favorable fluorescent properties have stimulated considerable effort to modulate their photoluminescence (PL) for bioimaging and sensing. However, the fluorescent mechanisms are still only partially understood due to the diverse physicochemical properties of CDs prepared by various synthesis methods and postpreparation processes. In this report, pressure-induced bifurcation of PL is reported in red carbon quantum dots (R-CDs) for the first time. The splitting of PL into an irreversible blue-shifted peak and a reversible red-shifted peak under pressure suggests the coexistence of multiple fluorescent mechanisms in R-CDs, i.e., emissions from surface groups and nitrogen-doped cores. The concentration and excitation laser energy dependencies of pressure-induced bifurcation, as well as the time-resolved PL, further support the coexistence of multiple emitters. Our results provide a method for distinguishing between the different fluorescent mechanisms related to surface groups and carbon cores in CDs.

Nanoscale bioconjugates: A review of the structural attributes of drug-loaded nanocarrier conjugates for selective cancer therapy

Nanobioconjugates are nanoscale drug delivery vehicles that have been conjugated to or decorated with biologically active targeting ligands. These targeting ligands can be antibodies, peptides, aptamers, or small molecules such as vitamins or hormones. Most research studies in this field have been devoted to targeting cancer. Moreover, the nanostructures can be designed with an additional level of targeting by being designed to be stimulus-responsive or "smart" by a judicious choice of materials to be incorporated into the hybrid nanostructures. This stimulus could be an acidic pH, raised temperature, enzyme, ultrasound, redox potential, an externally applied magnetic field, or laser irradiation. In this case, the smart capability can increase the accumulation at the tumor site or the on-demand drug release, while the ligand ensures selective binding to the tumor cells. The present review highlights some interesting studies classified according to the nanostructure material. These materials include natural substances (polysaccharides), multi-walled carbon nanotubes (and halloysite nanotubes), metal-organic frameworks and covalent-organic frameworks, metal nanoparticles (gold and silver), and polymeric micelles.

A Strategic Review on Carbon Quantum Dots for Cancer-Diagnostics and Treatment

The understanding of the genesis of life-threatening cancer and its invasion calls for urgent development of novel technologies for real-time observations, early diagnosis, and treatment. Quantum dots (QDs) grabbed the spotlight in oncology owing to their excellent photostability, bright fluorescence, high biocompatibility, good electrical and chemical stability with minimum invasiveness. Recently, carbon QDs (CQDs) have become popular over toxic inorganic QDs in the area of bioimaging, biosensing, and drug delivery. Further, CQDs derived from natural sources like biomolecules and medicinal plants have drawn attention because of their one-pot, low-cost and ease of synthesis, along with remarkable tunable optical properties and biocompatibility. This review introduces the synthesis and properties of CQDs derived from natural sources, focusing on the applicability of CQD-based technologies as nano-theranostics for the diagnosis and treatment of cancer. Furthermore, the current issues and future directions for the transformation of CQDs-based nanotechnologies to clinical applications are highlighted.

Fluorescent Carbon Dot-Supported Imaging-Based Biomedicine: A Comprehensive Review

Carbon dots (CDs) provide distinctive advantages of strong fluorescence, good photostability, high water solubility, and outstanding biocompatibility, and thus are widely exploited as potential imaging agents for in vitro and in vivo bioimaging. Imaging is absolutely necessary when discovering the structure and function of cells, detecting biomarkers in diagnosis, tracking the progress of ongoing disease, treating various tumors, and monitoring therapeutic efficacy, making it an important approach in modern biomedicine. Numerous investigations of CDs have been intensively studied for utilization in bioimaging-supported medical sciences. However, there is still no article highlighting the potential importance of CD-based bioimaging to support various biomedical applications. Herein, we summarize the development of CDs as fluorescence (FL) nanoprobes with different FL colors for potential bioimaging-based applications in living cells, tissue, and organisms, including the bioimaging of various cell types and targets, bioimaging-supported sensing of metal ions and biomolecules, and FL imaging-guided tumor therapy. Current CD-based microscopic techniques and their advantages are also highlighted. This review discusses the significance of advanced CD-supported imaging-based in vitro and in vivo investigations, suggests the potential of CD-based imaging for biomedicine, and encourages the effective selection and development of superior probes and platforms for further biomedical applications.

Carbon Dot Therapeutic Platforms: Administration, Distribution, Metabolism, Excretion, Toxicity, and Therapeutic Potential

Ultrasmall nanoparticles are often grouped under the broad umbrella term of "nanoparticles" when reported in the literature. However, for biomedical applications, their small sizes give them intimate interactions with biological species and endow them with unique functional physiochemical properties. Carbon quantum dots (CQDs) are an emerging class of ultrasmall nanoparticles which have demonstrated considerable biocompatibility and have been employed as potent theragnostic platforms. These particles find application for increasing drug solubility and targeting, along with facilitating the passage of drugs across impermeable membranes (i.e., blood brain barrier). Further functionality can be triggered by various environmental conditions or external stimuli (i.e., pH, temperature, near Infrared (NIR) light, ultrasound), and their intrinsic fluorescence is valuable for diagnostic applications. The focus of this review is to shed light on the therapeutic potential of CQDs and identify how they travel through the body, reach their site of action, administer therapeutic effect, and are excreted. Investigation into their toxicity and compatibility with larger nanoparticle carriers is also examined. The future of CQDs for theragnostic applications is promising due to their multifunctional attributes and documented biocompatibility. As nanomaterial platforms become more commonplace in clinical treatments, the commercialization of CQD therapeutics is anticipated.

Nitrogen-Doped Carbon Dots as a Fluorescent Probe for the Highly Sensitive Detection of Bilirubin and Cell Imaging

Nitrogen-doped carbon dots (NCDs) with bright blue fluorescence were constructed by a hydrothermal method using sucrose and L-proline as raw materials. The NCDs were characterized by transmitted electron microscopy, X-ray diffractometry, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, and ultraviolet-visible absorption (UV-vis) and fluorescence spectroscopy to investigate the morphology, elemental composition, and optical properties. The NCDs had good water solubility, high dispersibility with an average diameter of only 1.7 nm, and satisfactory optical properties with a fluorescence quantum yield of 23.4%. The NCDs were employed for the detection of bilirubin. A good linear response of the NCDs in the range 0.35-9.78 μM was obtained for bilirubin with a detection limit of 33 nM. The NCDs were also applied to the analysis of real samples, serum and urine, with a recovery of 95.34%-104.66%. The low cytotoxicity and good biocompatibility of the NCDs were indicated by an MTT assay and cell imaging of HeLa cells. Compared with other detection systems, using NCDs for bilirubin detection was a facile and efficient method with good selectivity and sensitivity.

Fluorescence immunoassay for the targeted determination of trace Listeria monocytogenes based on immunomagnetic separation and CdZnTe quantum dot indication

Infections from invasive Listeria monocytogenes (L. monocytogenes) frequently occur in food and can cause high morbidity and death. Thus, the sensitive, specific, and rapid detection of L. monocytogenes is critical for ensuring food safety and public health. Herein, a fluorescence immunoassay for trace L. monocytogenes detection was designed based on guinea pig antibody-functionalized magnetic nanoparticles (Fe₃O₄ NPs/pAb1) and rabbit antibody-anchored CdZnTe quantum dots (CdZnTe QDs/pAb2). Because of the antibody-directed magnetic separation and long-wave fluorescent emission for CdZnTe QD indication, the constructed immunoassay strategy presented excellent anti-interference performance toward a biological matrix. The immunosensor exhibited a wide detection range of 1 to 10⁹ CFU mL^-1 for L. monocytogenes and a low limit of detection (LOD) of 1 CFU mL^-1, achieving an exceptionally sensitive detection of trace L. monocytogenes. Meanwhile, the immunosensor showed good specificity and had a short time-consumption of 60 min to realize the accurate determination of trace Listeria monocytogenes in spiked tap water and pasteurized milk samples.

Heavy metal ion detection using green precursor derived carbon dots

The discovery of carbon dots (CDs) for environmental remediation has gained awareness because of the diverse economically viable and environmental friendly green precursors generated from biowastes and biomass compared to the toxic inorganic quantum dots and CDs prepared from chemical precursors. This review presents the recent progress in green CDs, including their synthesis methods and sensing applications for the detection of heavy metal ions such as Iron (III), Mercury (II), Copper (II), Chromium (VI), Lead (II), Arsenic (III), Cobalt (II), Aluminum (III), Silver (I), and Gold (III) which are prominent environmental pollutants. The comparison based on selectivity, sensitivity, quantum yield, detection limit, linear concentration range, and sensing mechanisms are also reported. This review also covers the performance of doped green CDs using heteroatoms, toward the detection of heavy metal ions. Apart from the future perspectives, this review provides a general guide to use such environmental friendly CDs to detect harmful pollutants.

Two-photon excitable membrane targeting polyphenolic carbon dots for long-term imaging and pH-responsive chemotherapeutic drug delivery for synergistic tumor therapy

Long-term dynamic tracking of cells with theranostics properties remains challenging due to difficulty in preparing and delivering drugs by the probes. Herein, we developed a highly fluorescent one- and two-photon...

Bismuth- and gadolinium-codoped carbon quantum dots with red/green dual emission for fluorescence/CT/T1-MRI mode imaging

The synthesized novel Bi,Gd-CQDs exhibit red and green fluorescence, enabling CT and MR imaging, and providing an approach for multifunctional biological imaging.

Moxifloxacin detection based on fluorescence resonance energy transfer from carbon quantum dots to moxifloxacin using a ratiometric fluorescence probe

With an increase in the MOX concentration, the fluorescence intensity of CQDs decreases, whereas the fluorescence intensity of MOX increases gradually.