Copper-Doped Carbon Dots for Optical Bioimaging and Photodynamic Therapy

Portable hydrogel kit driven by bimetallic carbon dots nanozyme for H2O2-self-supplying dual-modal monitoring of atmospheric CH3SH

Due to the typical volatility of gaseous pollutant methyl mercaptan (CH3SH), the development of a facile, reliable, and accurate onsite environmental surveillance of highly toxic CH3SH faces many challenges, but it is critical to environmental atmosphere assessment and safeguarding public health. Here, we prepared a novel bimetallic carbon dots (Fe&Cu@CDs) nanozyme with high peroxidase-mimicking activity to design a portable hydrogel kit for onsite visual H2O2-self-supplying enzymatic cascade catalytic colorimetric and photothermal signal synergistic amplification dual-modal monitoring of CH3SH in atmospheric environment. Assisted by alcohol oxidase (AOX), CH3SH could be specifically converted into H2O2 for oxidizing chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) catalyzed by Fe&Cu@CDs to produce dark blue ox-TMB with absorption at 652 nm and photothermal characters. Consequently, a CH3SH concentration-dependent change both in naked-eye color and photothermal effect-triggered temperature were observed. By hybridizing AOX-assisted Fe&Cu@CDs + TMB with agarose, a H2O2-self-supplying colorimetric and photothermal signal synergistic amplification sensory hydrogel kit integrated with Color Picker APP-installed smartphone and 660 nm laser-equipped handheld thermal imager for CH3SH was proposed with acceptable results in atmospheric environment around wastepile (e.g., solid waste and food waste piles), which exhibited great potentials to further develop commercial onsite monitoring platforms in warning-early abnormal atmospheric CH3SH for safeguarding environmental health.

Unveiling the promising anticancer effect of copper-based compounds: a comprehensive review

Copper is a necessary micronutrient for maintaining the well-being of the human body. The biological activity of organic ligands, especially their anticancer activity, is often enhanced when they coordinate with copper(I) and (II) ions. Copper and its compounds are capable of inducing tumor cell death through various mechanisms of action, including activation of apoptosis signaling pathways by reactive oxygen species (ROS), inhibition of angiogenesis, induction of cuproptosis, and paraptosis. Some of the copper complexes are currently being evaluated in clinical trials for their ability to map tumor hypoxia in various cancers, including locally advanced rectal cancer and bulky tumors. Several studies have shown that copper nanoparticles can be used as effective agents in chemodynamic therapy, phototherapy, hyperthermia, and immunotherapy. Despite the promising anticancer activity of copper-based compounds, their use in clinical trials is subject to certain limitations. Elevated copper concentrations may promote tumor growth, angiogenesis, and metastasis by affecting cellular processes.

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.

The future of plant based green carbon dots as cancer Nanomedicine: From current progress to future Perspectives and beyond

BACKGROUND

The emergence of carbon dots (CDs) as anticancer agents had sparked a transformation in cancer research and treatment strategies. These fluorescent CDs, initially introduced in the early 2000 s, possess exceptional biocompatibility, tunable fluorescence, and surface modification capabilities, positioning them as promising tools in biomedical applications.

AIM OF REVIEW

The review encapsulates the transformative trajectory of green CDs as future anticancer nanomedicine, poised to redefine the strategies employed in the ongoing fight against cancer.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The versatility of CDs was rooted in their various synthesis approaches and sustainable strategies, enabling their adaptability for diverse therapeutic uses. In vitro studies had showcased CDs' selective cytotoxicity against cancer cells while sparing healthy counterparts, forming the basis for targeted therapeutic potential. This selectivity had been attributed to the reactive oxygen species (ROS) generation, which opened avenues for targeted interventions. The role of CDs in combination therapies, synergizing with chemotherapy, radiotherapy, and targeted approaches was then investigated to heighten their anticancer efficacy. Notably, in vivo studies highlight CDs' remarkable biocompatibility and minimal side effects, endorsing their translational promise. Integration with conventional cancer treatments such as chemotherapy, radiotherapy, and immunotherapy amplified the versatility and effectiveness of CDs. The exploration of CDs' applications in photo-induced treatments further solidified their significance, positioning them as photosensitizers (PS) in photodynamic therapy (PDT) and photothermal agents (PA) in photothermal therapy (PTT). In PDT, CDs triggered the generation of ROS upon light exposure, facilitating cancer cell elimination, while in PTT, they induced localized hyperthermia within cancer cells, enhancing therapeutic outcomes. In vitro and in vivo investigations validated CDs' efficacy in PDT and PTT, affirming their potential for integration into combination therapies. Looking ahead, the future of CDs in anticancer treatment encompasses bioavailability, biocompatibility, synergistic treatments, tumor targeting, artificial intelligence (AI) and robotics integration, personalized medicine, and clinical translation. This transformative odyssey of CDs as future anticancer agents is poised to redefine the paradigm of cancer treatment strategies.

Cuproptosis: Unraveling the Mechanisms of Copper-Induced Cell Death and Its Implication in Cancer Therapy

Copper, an essential element for various biological processes, demands precise regulation to avert detrimental health effects and potential cell toxicity. This paper explores the mechanisms of copper-induced cell death, known as cuproptosis, and its potential health and disease implications, including cancer therapy. Copper ionophores, such as elesclomol and disulfiram, increase intracellular copper levels. This elevation triggers oxidative stress and subsequent cell death, offering potential implications in cancer therapy. Additionally, copper ionophores disrupt mitochondrial respiration and protein lipoylation, further contributing to copper toxicity and cell death. Potential targets and biomarkers are identified, as copper can be targeted to those proteins to trigger cuproptosis. The role of copper in different cancers is discussed to understand targeted cancer therapies using copper nanomaterials, copper ionophores, and copper chelators. Furthermore, the role of copper is explored through diseases such as Wilson and Menkes disease to understand the physiological mechanisms of copper. Exploring cuproptosis presents an opportunity to improve treatments for copper-related disorders and various cancers, with the potential to bring significant advancements to modern medicine.

Functionalized heteroatom-doped carbon dots for biomedical applications: A review

Carbon nanoparticles (CDs) have recently drawn a great attention in (bio)chemical analysis, sensing and bioimaging owing to their photostability, water stability, minimal toxicity, biocompatibility and ease of surface functionalization. While the vast majority of CDs applications rely on exploiting their fluorescent properties, doping such nanomaterials with various elements has recently received increasing attention as an effective approach to modify their optoelectronic characteristics, introducing novel improved optical features such as phosphorescence, upconversion luminescence or multimodal imaging capabilities. This review article focuses in the recent advances on the synthesis of heteroatom-doped CDs, exhibiting distinctive features of high value for sensing and imaging, as well as various functionalization schemes developed for guided analyte labeling. Relevant applications in chemical sensing, bioimaging and disease therapy are here presented. A final section intends to provide an overview towards future developments of such emerging light-emitting nanomaterials in the design of future devices and strategies for (bio)analytical chemistry.

An insight into recent developments of copper, silver and gold carbon dots: cancer diagnostics and treatment

Cancer is one of the most fatal diseases globally, however, advancement in the field of nanoscience specifically novel nanomaterials with nano-targeting of cancer cell lines has revolutionized cancer diagnosis and therapy and has thus attracted the attention of researchers of related fields. Carbon Dots (CDs)-C-based nanomaterials-have emerged as highly favorable candidates for simultaneous bioimaging and therapy during cancer nano-theranostics due to their exclusive innate FL and theranostic characteristics exhibited in different preclinical results. Recently, different transition metal-doped CDs have enhanced the effectiveness of CDs manifold in biomedical applications with minimum toxicity. The use of group-11 (Cu, Ag and Au) with CDs in this direction have recently gained the attention of researchers because of their encouraging results. This review summarizes the current developments of group-11 (Cu, Ag and Au) CDs for early diagnosis and therapy of cancer including their nanocomposites, nanohybrids and heterostructures etc. All The manuscript highlights imaging applications (FL, photoacoustic, MRI etc.) and therapeutic applications (phototherapy, photodynamic, multimodal etc.) of Cu-, Ag- and Au-doped CDs reported as nanotheranostic agents for cancer treatment. Sources of CDs and metals alogwith applications to give a comparative analysis have been given in the tabulated form at the end of manuscript. Further, future prospects and challenges have also been discussed.

Persistent luminescent nanophosphors for applications in cancer theranostics, biomedical, imaging and security

The extraordinary and unique properties of persistent luminescent (PerLum) nanostructures like storage of charge carriers, extended afterglow, and some other fascinating characteristics like no need for in-situ excitation, and rechargeable luminescence make such materials a primary candidate in the fields of bio-imaging and therapeutics. Apart from this, due to their extraordinary properties they have also found their place in the fields of anti-counterfeiting, latent fingerprinting (LPF), luminescent markings, photocatalysis, solid-state lighting devices, glow-in-dark toys, etc. Over the past few years, persistent luminescent nanoparticles (PLNPs) have been extensively used for targeted drug delivery, bio-imaging guided photodynamic and photo-thermal therapy, biosensing for cancer detection and subsequent treatment, latent fingerprinting, and anti-counterfeiting owing to their enhanced charge storage ability, in-vitro excitation, increased duration of time between excitation and emission, low tissue absorption, high signal-to-noise ratio, etc. In this review, we have focused on most of the key aspects related to PLNPs, including the different mechanisms leading to such phenomena, key fabrication techniques, properties of hosts and different activators, emission, and excitation characteristics, and important properties of trap states. This review article focuses on recent advances in cancer theranostics with the help of PLNPs. Recent advances in using PLNPs for anti-counterfeiting and latent fingerprinting are also discussed in this review.

Encapsulation of thymol and menthol loaded N/S co-doped carbon dots derived from a mixture of herbal extracts as theranostic agents with anticancer properties

This research was conducted by synthesizing carbon dots MNE-CDs (mixed natural extract-carbon dots) based on mixed natural extract (ginger, garlic, turmeric) through the hydrothermal routh. Menthol and thymol were loaded as multi-therapeutic drugs with the addition of the bio-enhancer loaded on MNE-CDs with the hydrothermal method during a separate stage. These nanostructures were successfully encapsulated in chitosan by the nanospray drying method to enhance sustainability and release control. This study answered three of these issues by fabricating novel carbon dots for anticancer potential, release behavior and bioimaging at the same time. Preparation carbon dots are characterized using UV-vis, PL, FE-SEM, DLS, EDX, and FT-IR analysis. A moderate and sustained release profile of encapsulated carbon dots was noticed in comparison to the free carbon dots over 48 h of study in both simulated physicological environment (pH 7.4) and tumor tissue (pH 5.2) conditions. It was found that the release of bioactive substances from encapsulated samples was significantly attenuated. The cell viability assay showed all the samples, including free and encapsulated carbon dots, offered acceptable cytotoxicity against MCF-7 breast cancer cells. Despite this, the toxicity of free carbon dots is more than the encapsulated samples, and also the enhancement in anticancer potential was not observed for carbon dots loaded with menthol and thymol. Upon the obtained results, the synthesized fluorescence N/S co-doped carbon dots hold great anticancer potential and biological fluorescent labeling.

Functionalized Fe-Doped Carbon Dots Exhibiting Dual Glutathione Consumption to Amplify Ferroptosis for Enhanced Cancer Therapy

Nonapoptotic ferroptosis is a promising cancer treatment which offers a solution to the multidrug resistance of conventional apoptosis-induced programmed cancer cell death therapies. Reducing intracellular glutathione (GSH) is essential for inducing excess ROS and has been considered a crucial process to trigger ferroptosis. However, treatments reducing GSH alone have not produced satisfactory effects due to their restricted target. In this regard, FeCDs (Fe3+-modified l-histidine -sourced carbon dots) with dual GSH-consumption capabilities were constructed to engineer ferroptosis by self-amplifying intratumoral oxidative stress. Carbon dots have the ability to consume GSH, and the introduction of Fe3+ can amplify the GSH-consuming ability of CDs, reacting with excess H2O2 in the tumor microenvironment to generate highly oxidized •OH. This is a novel strategy through synergistic self-amplification therapy combining Fe3+ and CDs with GSH-consuming activity. The acid-triggered degradation material (FeCDs@PAE-PEG) was prepared by encapsulating FeCDs in an oil-in-water manner. Compared with other ferroptosis-triggering nanoparticles, the established FeCDs@PAE-PEG is targeted and significantly enhances the consumption efficiency of GSH and accumulation of excess iron without the involvement of infrared light and ultrasound. This synergistic strategy exhibits excellent ferroptosis-inducing ability and antitumor efficacy both in vitro and in vivo and offers great potential for clinical translation of ferroptosis.

Zero-Dimensional Carbon Nanomaterials for Fluorescent Sensing and Imaging

Advances in nanotechnology and nanomaterials have attracted considerable interest and play key roles in scientific innovations in diverse fields. In particular, increased attention has been focused on carbon-based nanomaterials exhibiting diverse extended structures and unique properties. Among these materials, zero-dimensional structures, including fullerenes, carbon nano-onions, carbon nanodiamonds, and carbon dots, possess excellent bioaffinities and superior fluorescence properties that make these structures suitable for application to environmental and biological sensing, imaging, and therapeutics. This review provides a systematic overview of the classification and structural properties, design principles and preparation methods, and optical properties and sensing applications of zero-dimensional carbon nanomaterials. Recent interesting breakthroughs in the sensitive and selective sensing and imaging of heavy metal pollutants, hazardous substances, and bioactive molecules as well as applications in information encryption, super-resolution and photoacoustic imaging, and phototherapy and nanomedicine delivery are the main focus of this review. Finally, future challenges and prospects of these materials are highlighted and envisaged. This review presents a comprehensive basis and directions for designing, developing, and applying fascinating fluorescent sensors fabricated based on zero-dimensional carbon nanomaterials for specific requirements in numerous research fields.

In Situ Radical Reaction-Modified Carbon Dot Nanocapsules with Macrophage Escape and Prolonged Imaging

Carbon dots (CDs) have emerged as an extremely promising platform for biological imaging, owing to their optical properties and low toxicity. However, one of the major challenges in utilizing CDs for in vivo imaging is their high immunogenicity and rapid clearance, which limits their potential. Herein, a novel approach for mitigating these issues is presented through the development of carbon dot nanocapsules (nCDs). Specifically, CDs are encapsulated within a zwitterionic polymer shell composed of 2-methacryloyloxyethyl phosphorylcholine (MPC) to create nCDs with a size of ≈40 nm. Notably, the nCDs exhibit excitation-dependent photoluminescence behavior in the range of 550-600 nm, with tunability based on the excitation wavelength. In confocal imaging, CDs display a strong fluorescence signal after 8 h of incubation with phagocytes, while nCDs show minimal signal, suggesting that nCDs may be capable of evading phagocyte uptake. Furthermore, imaging studies in zebrafish demonstrate that nCDs exhibit a retention time >10 times longer than that of CDs, with fluorescence intensity remaining at 81% after 10 h compared to only 8% for CDs. Taken together, the study presents a novel approach for enhancing the performance of CDs in in vivo imaging applications, offering significant potential for clinical translation.

Copper-instigated modulatory cell mortality mechanisms and progress in oncological treatment investigations

Copper, a transition metal, serves as an essential co-factor in numerous enzymatic active sites and constitutes a vital trace element in the human body, participating in crucial life-sustaining activities such as energy metabolism, antioxidation, coagulation, neurotransmitter synthesis, iron metabolism, and tetramer deposition. Maintaining the equilibrium of copper ions within biological systems is of paramount importance in the prevention of atherosclerosis and associated cardiovascular diseases. Copper induces cellular demise through diverse mechanisms, encompassing reactive oxygen species responses, apoptosis, necrosis, pyroptosis, and mitochondrial dysfunction. Recent research has identified and dubbed a novel regulatory cell death modality-"cuprotosis"-wherein copper ions bind to acylated proteins in the tricarboxylic acid cycle of mitochondrial respiration, resulting in protein aggregation, subsequent downregulation of iron-sulfur cluster protein expression, induction of proteotoxic stress, and eventual cell death. Scholars have synthesized copper complexes by combining copper ions with various ligands, exploring their significance and applications in cancer therapy. This review comprehensively examines the multiple pathways of copper metabolism, copper-induced regulatory cell death, and the current status of copper complexes in cancer treatment.

Insights into the antibacterial mechanism of iron doped carbon dots

Antibacterial nanomaterials provide promising alternative strategies to combat the bacterial infection due to deteriorating resistance. However, few have been practically applied due to the lack of clear antibacterial mechanisms. In this work, we selected good-biocompatibility iron-doped CDs (Fe-CDs) with antibacterial activity as a comprehensive research model to systematically reveal the intrinsic antibacterial mechanism. Through energy dispersive spectroscopy (EDS) mapping of in situ ultrathin sections of bacteria, we found that a large amount of iron was accumulated inside the bacteria treated with Fe-CDs. Then, combining the data of cell level and transcriptomics, it can be elucidated that Fe-CDs could interact with cell membranes, enter bacterial cells through iron transport and infiltration, increase intracellular iron levels, trigger increased reactive oxygen species (ROS), and lead to disruption of Glutathione (GSH)-dependent antioxidant mechanisms. Excessive ROS further leads to lipid peroxidation and DNA damage in cells, lipid peroxidation destroys the integrity of the cell membrane, and finally leads to the leakage of intracellular substances resulting in bacterial growth inhibition and death. This result provides important insights into the antibacterial mechanism of Fe-CDs and further provides a basis for the deep application of nanomaterials in biomedicine.

Smart Nanomaterials in Cancer Theranostics: Challenges and Opportunities

Cancer is ranked as the second leading cause of death globally. Traditional cancer therapies including chemotherapy are flawed, with off-target and on-target toxicities on the normal cells, requiring newer strategies to improve cell selective targeting. The application of nanomaterial has been extensively studied and explored as chemical biology tools in cancer theranostics. It shows greater applications toward stability, biocompatibility, and increased cell permeability, resulting in precise targeting, and mitigating the shortcomings of traditional cancer therapies. The nanoplatform offers an exciting opportunity to gain targeting strategies and multifunctionality. The advent of nanotechnology, in particular the development of smart nanomaterials, has transformed cancer diagnosis and treatment. The large surface area of nanoparticles is enough to encapsulate many molecules and the ability to functionalize with various biosubstrates such as DNA, RNA, aptamers, and antibodies, which helps in theranostic action. Comparatively, biologically derived nanomaterials perceive advantages over the nanomaterials produced by conventional methods in terms of economy, ease of production, and reduced toxicity. The present review summarizes various techniques in cancer theranostics and emphasizes the applications of smart nanomaterials (such as organic nanoparticles (NPs), inorganic NPs, and carbon-based NPs). We also critically discussed the advantages and challenges impeding their translation in cancer treatment and diagnostic applications. This review concludes that the use of smart nanomaterials could significantly improve cancer theranostics and will facilitate new dimensions for tumor detection and therapy.

Nitrogen and copper-doped saffron-based carbon dots: Synthesis, characterization, and cytotoxic effects on human colorectal cancer cells

AIM

Doped carbon dots (CDs) have attracted tremendous attention in cancer therapy. We aimed to synthesize copper, nitrogen-doped carbon dots (Cu, N-CDs) from saffron and investigated their effects on HCT-116 and HT-29 colorectal cancer (CRC) cells.

MAIN METHODS

CDs were synthesized by hydrothermal method and characterized by transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy, and fluorescence spectroscopy. HCT-116 and HT-29 cells were incubated with saffron, N-CDs, and Cu, N-CDs for 24 and 48 h for cell viability. Cellular uptake and intracellular reactive oxygen species (ROS) were evaluated by immunofluorescence microscopy. Oil Red O staining was used to monitor lipid accumulation. Apoptosis was evaluated using acridine orange/propidium iodide (AO/PI) staining and quantitative real-time polymerase chain reaction (Q-PCR) assay. The expression of miRNA-182 and miRNA-21 was measured by Q-PCR, while the generation of nitric oxide (NO) and lysyl oxidase (LOX) activity was calculated by colorimetric methods.

KEY FINDINGS

CDs were successfully prepared and characterized. Cell viability decreased in the treated cells dose- and time-dependently. HCT-116 and HT-29 cells uptook Cu, N-CDs with a high level of ROS generation. The Oil Red O staining showed lipid accumulation. Concomitant with an up-regulation of apoptotic genes (p < 0.05), AO/PI staining showed increased apoptosis in the treated cells. In comparison to control cells, NO generation, and miRNA-182 and miRNA-21 expression significantly changed in the Cu, N-CDs treated cells (p < 0.05).

SIGNIFICANCE

The results indicated that Cu, N-CDs could inhibit CRC cells through the induction of ROS generation and apoptosis.

Lights and Dots toward Therapy-Carbon-Based Quantum Dots as New Agents for Photodynamic Therapy

The large number of deaths induced by carcinoma and infections indicates that the need for new, better, targeted therapy is higher than ever. Apart from classical treatments and medication, photodynamic therapy (PDT) is one of the possible approaches to cure these clinical conditions. This strategy offers several advantages, such as lower toxicity, selective treatment, faster recovery time, avoidance of systemic toxic effects, and others. Unfortunately, there is a small number of agents that are approved for usage in clinical PDT. Novel, efficient, biocompatible PDT agents are, thus, highly desired. One of the most promising candidates is represented by the broad family of carbon-based quantum dots, such as graphene quantum dots (GQDs), carbon quantum dots (CQDs), carbon nanodots (CNDs), and carbonized polymer dots (CPDs). In this review paper, these new smart nanomaterials are discussed as potential PDT agents, detailing their toxicity in the dark, and when they are exposed to light, as well as their effects on carcinoma and bacterial cells. The photoinduced effects of carbon-based quantum dots on bacteria and viruses are particularly interesting, since dots usually generate several highly toxic reactive oxygen species under blue light. These species are acting as bombs on pathogen cells, causing various devastating and toxic effects on those targets.

Preparation of Ciprofloxacin-Based Carbon Dots with High Antibacterial Activity

Nowadays, bacterial infections are attracting great attention for the research and development of new antimicrobial agents. As one of the quinolones, ciprofloxacin (CI) has a broad-spectrum, strong antibacterial effect. However, the clinical use of ciprofloxacin is limited by drug resistance. Ciprofloxacin carbon dots (CCDs) with enhanced antibacterial activity and copper-doped ciprofloxacin carbon dots (Cu-CCDs) were synthesized by a simple hydrothermal method. The results of structural analysis and antibacterial experiments show that CCDs and Cu-CCDs have effective antibacterial properties by retaining the active groups of ciprofloxacin (-COOH, C-N, and C-F), and Cu-CCDs doped with copper have a better antibacterial effect. In addition, experiments have shown that Cu-CCDs show excellent antibacterial activity against E. coli and S. aureus and have good biocompatibility, which indicates that they have great prospects in clinical applications. Therefore, novel modified copper CCDs with broad-spectrum antibacterial activity, which can be used as antibacterial nanomaterials for potential applications in the field of antibacterial drugs, were synthesized in this study.

Recent Advances in Cancer Therapeutic Copper-Based Nanomaterials for Antitumor Therapy

Copper serves as a vital microelement which is widely present in the biosystem, functioning as multi-enzyme active site, including oxidative stress, lipid oxidation and energy metabolism, where oxidation and reduction characteristics are both beneficial and lethal to cells. Since tumor tissue has a higher demand for copper and is more susceptible to copper homeostasis, copper may modulate cancer cell survival through reactive oxygen species (ROS) excessive accumulation, proteasome inhibition and anti-angiogenesis. Therefore, intracellular copper has attracted great interest that multifunctional copper-based nanomaterials can be exploited in cancer diagnostics and antitumor therapy. Therefore, this review explains the potential mechanisms of copper-associated cell death and investigates the effectiveness of multifunctional copper-based biomaterials in the field of antitumor therapy.

Lipid-coated red fluorescent carbon dots for imaging and synergistic phototherapy in breast cancer

The synthesis of carbon dots using plant leaves is a facile and economically viable approach. Here we report the development of lipid-coated red fluorescent carbon dots (LRCDs), a biocompatible and stable nanomaterial, utilizing Clitoria ternatea leaves. The red fluorescent carbon dots (RCDs) were prepared by hydrothermal method, followed by lipid coating using rotary evaporation for imaging-guided phototherapy. RCDs generate heat in tandem with NIR laser irradiation and could therefore be employed as a photothermal agent in cancer therapy. Additionally, the fluorescent nature of RCDs can be utilized in bioimaging. The fabricated RCDs displayed a characteristic fluorescent emission maximum at 672 nm with a shoulder peak at 723 nm. Hydrophobicity is a major drawback associated with the RCDs, which limits their therapeutic efficiency due to poor biodistribution and rapid clearance. To address this limitation, we coated RCDs with soya lecithin to generate hydrophilic LRCDs with better bioavailability and therapeutic effectiveness. Further analysis using MTT assay reveals high biocompatibility and a distinct photothermal ablation potency of LRCDs against L929 and 4T1 cells, respectively. LRCDs could potentially be synthesized on a large scale and used for a variety of applications due to their low-cost, and biocompatibility.

Emerging and Versatile Platforms of Metal-Ion-Doped Carbon Dots for Biosensing, Bioimaging, and Disease Therapy

Metal ions possess abundant electrons and unoccupied orbitals, as well as large atomic radii, whose doping into carbon dots (CDs) is a facile strategy to endow CDs with additional physicochemical characteristics. After being doped with metal ions, CDs reveal obvious changes in their optical, electronic, and magnetic properties by adjustments to their electron density distribution and the energy gaps, leading them to be promising and competitive candidates as labeling probes, imaging agents, catalysts, nanodrugs, and so on. In this review, we summarize the fabrication methods of metal-ion-doped CDs (M-CDs), and highlight their biological applications including biosensing, bioimaging, tumor therapy, and anti-microbial treatment. Finally, the challenging future perspectives of M-CDs are analyzed. We hope this review will provide inspiration for further development of M-CDs in various biological aspects, and help readers who are interested in M-CDs and their biological applications.

Intense Blue Photo Emissive Carbon Dots Prepared through Pyrolytic Processing of Ligno-Cellulosic Wastes

In this work, Carbon Dots with intense blue photo-luminescent emission were prepared through a pyrolytic processing of forestry ligno-cellulosic waste. The preparation path is simple and straightforward, mainly consisting of drying and fine grinding of the ligno-cellulosic waste followed by thermal exposure and dispersion in water. The prepared Carbon Dots presented characteristic excitation wavelength dependent emission peaks ranging within 438-473 nm and a remarkable 28% quantum yield achieved at 350 nm excitation wavelength. Morpho-structural investigations of the prepared Carbon Dots were performed through EDX, FT-IR, Raman, DLS, XRD, and HR-SEM while absolute PLQY, steady state, and lifetime fluorescence were used to highlight their luminescence properties. Due to the wide availability of this type of ligno-cellulosic waste, an easy processing procedure achieved photo-luminescent properties, and the prepared Carbon Dots could be an interesting approach for various applications ranging from sensors, contrast agents for biology investigations, to photonic conversion mediums in various optoelectronic devices. Additionally, their biocompatibility and waste valorization in new materials might be equally good arguments in their favor, bringing a truly "green" approach.

Short-Wavelength Aggregation-Induced Emission Photosensitizers for Solid Tumor Therapy: Enhanced with White-Light Fiber Optic

Background

White-light photodynamic therapy (wPDT) has been used in the treatment of cancer due to its convenience, effectiveness and less painful. However, the limited penetration of white-light into the tissues leads to a reduced effectiveness of solid tumor treatment.

Methods

Two short-wavelength aggregation-induced emission (AIE) nanoparticles were prepared, PyTPA@PEG and TB@PEG, which have excitation wavelengths of 440 nm and 524 nm, respectively. They were characterized by UV, fluorescence, particle size and TEM. The ability of nanoparticles to produce reactive oxygen species (ROS) and kill cancer cells under different conditions was investigated in vitro, including white-light, after white-light penetrating the skin, laser. A white-light fiber for intra-tumor irradiation was customized. Finally, induced tumor elimination with fiber-mediated wPDT was confirmed in vivo.

Results

In vitro, both PyTPA@PEG and TB@PEG are more efficient in the production ROS when exposed to white-light compared to laser. However, wPDT also has a fatal flaw in that its level of ROS production after penetrating the skin is reduced to 20-40% of the original level. To this end, we have customized a white-light fiber for intra-tumor irradiation. In vivo, the fiber-mediated wPDT significantly induces tumor elimination with maximized therapeutic outcomes by irradiating the interior of the tumor. In addition, wPDT also has the advantage that its light source can be adapted to a wide range of photosensitizers (wavelength range 400-700 nm), whereas a laser of single wavelength can only target a specific photosensitizer.

Conclusion

This method of using optical fiber to increase the tissue penetration of white light can greatly improve the therapeutic effect of AIE photosensitizers, which is needed for the treatment of large/deep tumors and holds great promise in cancer treatment.

Emerging metal doped carbon dots for promising theranostic applications

As a bridge between organic fluorophores and inorganic quantum dots, carbon dots (CDs) have been recognized as emerging nanotheranostics for biomedical applications owing to their distinctive merits such as superior optical properties, flexible modification, adjustable functionalities, and remarkable photoactive therapeutic outcome, etc. Compared to metal free CDs, the introduction of metal ion in CDs endowed metal-doped CDs (MCDs) with tunable optical properties and new intrinsic properties, thereby illustrating its different capabilities from metal-free CDs for bioimaging and therapy. This review aims to summarize the recent progress of photonic MCDs as emerging nanoagent for theranostic application such as disease-related diagnostic (involving biosensing and bioimaging) and cancer therapy. The challenges and potential development of MCDs in nanotheranostic fields are also discussed.

Quantum Dots Mediated Imaging and Phototherapy in Cancer Spheroid Models: State of the Art and Perspectives

Quantum Dots (QDs) are fluorescent nanoparticles known for their exceptional optical properties, i.e., high fluorescence emission, photostability, narrow emission spectrum, and broad excitation wavelength. These properties make QDs an exciting choice for bioimaging applications, notably in cancer imaging. Challenges lie in their ability to specifically label targeted cells. Numerous studies have been carried out with QDs coupled to various ligands like peptides, antibodies, aptamers, etc., to achieve efficient targeting. Most studies were conducted in vitro with two-dimensional cell monolayers (n = 8902) before evolving towards more sophisticated models. Three-dimensional multicellular tumor models better recapitulate in vivo conditions by mimicking cell-to-cell and cell-matrix interactions. To date, only few studies (n = 34) were conducted in 3D in vitro models such as spheroids, whereas these models could better represent QDs behavior in tumors compared to monolayers. Thus, the purpose of this review is to present a state of the art on the studies conducted with Quantum Dots on spheroid models for imaging and phototherapy purposes.

Green Synthesis of Near-Infrared Copper-Doped Carbon Dots from Alcea for Cancer Photothermal Therapy

Heteroatom-doped carbon dots (CDs) with optical absorbance in the near-infrared (NIR) region can provide an opportunity for selective cancer photothermal therapy (PTT). Here, an eco-friendly, simple, cost-efficient, and one-step hydrothermal method was developed to synthesize copper-doped CDs (Cu-doped CDs). The Alcea extract as the carbon source was combined with CuSO₄ as the dopant. Microscopic and spectroscopic analyses showed that spherical and monodisperse Cu-doped CDs (Cu-dCDs) with sizes below 10 nm have bright fluorescence with photoluminescence quantum yields of 11.1%. Cu-dCDs exhibited an excellent single absorbance peak at 800 nm and strong emission at 460 nm when excited at 370 nm. In vitro low cytotoxicity and the Cu-dCD-mediated cell PTT with the photothermal conversion efficiency (39.3%) show that cell internalization of Cu-doped CDs under an 800 nm NIR laser can induce cell thermal death.

Semiconductor quantum dots for photodynamic therapy: Recent advances

Photodynamic therapy is a promising cancer treatment that induces apoptosis as a result of the interactions between light and a photosensitizing drug. Lately, the emergence of biocompatible nanoparticles has revolutionized the prospects of photodynamic therapy (PDT) in clinical trials. Consequently, a lot of research is now being focused on developing non-toxic, biocompatible nanoparticle-based photosensitizers for effective cancer treatments using PDT. In this regard, semiconducting quantum dots have shown encouraging results. Quantum dots are artificial semiconducting nanocrystals with distinct chemical and physical properties. Their optical properties can be fine-tuned by varying their size, which usually ranges from 1 to 10 nm. They present many advantages over conventional photosensitizers, mainly their emission properties can be manipulated within the near IR region as opposed to the visible region by the former. Consequently, low intensity light can be used to penetrate deeper tissues owing to low scattering in the near IR region. Recently, successful reports on imaging and PDT of cancer using carbon (carbon, graphene based) and metallic (Cd based) based quantum dots are promising. This review aims to summarize the development and the status quo of quantum dots for cancer treatment.

Copper-based nanomaterials for cancer theranostics

Copper-based nanomaterials (Cu-based NMs) with favorable biocompatibility and unique properties have attracted the attention of many biomedical researchers. Cu-based NMs are one of the most widely studied materials in cancer treatment. In recent years, great progress has been made in the field of biomedicine, especially in the treatment and diagnosis of tumors. This review begins with the classification of Cu-based NMs and the recent synthetic strategies of Cu-based NMs. Then, according to the abundant and special properties of Cu-based NMs, their application in biomedicine is summarized in detail. For biomedical imaging, such as photoacoustic imaging, positron emission tomography imaging, and multimodal imaging based on Cu-based NMs are summarized, as well as strategies to improve the diagnostic effectiveness. Moreover, a series of unique structures and functions as well as the underlying property activity relationship of Cu-based NMs were shown to highlight their promising therapeutic performance. Cu-based NMs have been widely used in monotherapies, such as photothermal therapy (PTT) and chemodynamic therapy (CDT). Moreover, the sophisticated design in composition, structure, and surface fabrication of Cu-based NMs can endow these NMs with more modalities in cancer diagnosis and therapy. To further improve the efficiency of cancer treatment, combined therapy based on Cu-based NMs was introduced in detail. Finally, the challenges, critical factors, and future prospects for the clinical translation of Cu-based NMs as multifunctional theranostic agents were also considered and discussed. The aim of this review is to provide a better understanding and key consideration for the rational design of this increasingly important new paradigm of Cu-based NMs as theranostic agents. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

Light-triggered photodynamic nanomedicines for overcoming localized therapeutic efficacy in cancer treatment

Photodynamic nanomedicines have significantly enhanced the therapeutic efficacy of photosensitizers (PSs) by overcoming critical limitations of PSs such as poor water solubility and low tumor accumulation. Furthermore, functional photodynamic nanomedicines have enabled overcoming oxygen depletion during photodynamic therapy (PDT) and tissue light penetration limitation by supplying oxygen or upconverting light in targeted tumor tissues, resulting in providing the potential to overcome biological therapeutic barriers of PDT. Nevertheless, their localized therapeutic effects still remain a huddle for the effective treatment of metastatic- or recurrent tumors. Recently, newly designed photodynamic nanomedicines and their combination chemo- or immune checkpoint inhibitor therapy enable the systemic treatment of various metastatic tumors by eliciting antitumor immune responses via immunogenic cell death (ICD). This review introduces recent advances in photodynamic nanomedicines and their applications, focusing on overcoming current limitations. Finally, the challenges and future perspectives of the clinical translation of photodynamic nanomedicines in cancer PDT are discussed.

Green synthesis of broccoli-derived carbon quantum dots as effective photosensitizers for the PDT effect testified in the model of mutant Caenorhabditis elegans

The clinical application of photodynamic therapy (PDT) is still limited because of the drawbacks of the traditional photosensitizers, such as low singlet oxygen (¹O₂) quantum yield and the problem of photobleaching. Herein, carbon quantum dots (CQDs) derived from broccoli natural biomass as a carbon source were fabricated via a simple hydrothermal method and showed outstanding PDT ability as an effective photodynamic agent tested in Caenorhabditis elegans (C. elegans) models. The as-prepared broccoli-derived CQDs (BCQDs) showed excellent water solubility and optical properties and could generate singlet oxygen (¹O₂) effectively under irradiated light with a wavelength of 660 nm. The in vivo experiment revealed that the PDT efficiency of the BCQDs was dependent on the induction of germline apoptosis through the cep-1/p53 pathway. Further investigation confirmed the DNA damage of the worm by the BCQDs after sufficient light irradiation, which was tested by measuring the egl-1-fold induction in hus-1(op244), and cep-1(w40) mutants that have a loss of function in the genes involved in DNA damage response such as hus-1 (DNA checkpoint gene) and cep-1/p53 (tumor suppressor). The lack of germline apoptosis in the loss of function mutants egl-1(n487), hus-1(op244), and cep-1(w40) exposed to light irradiation compared with the control proved the necessity of these genes in DNA damage-induced germline apoptosis. Therefore, this work has not only provided a new photodynamic agent but also introduced C. elegans as an easy and high-throughput model for the rapid evaluation of the efficiency of PDT.

Carbon Dots in Biomedicine: A Review

Despite the rapid development of science and technology, the effective treatment of cancer still threatens human life and health. However, the success of cancer treatment is closely related to early diagnosis, identification, and effective treatment. In recent years, with the strengthening of the development and research of nanomaterials for cancer diagnosis and treatment, researchers have found that carbon dots (CDs) have the advantages of wide absorption, excellent biocompatibility, diverse imaging characteristics, and photostability and are widely used in various fields, such as sensing, imaging, and drug/gene transportation. Recently, researchers also discovered that CDs could be used as an effective photosensitizer to generate active oxygen or convert light energy into heat under the stimulation of the external lasers, making them have the effects of photothermal and photodynamic therapy for cancer. In this review, we first outline the single-modal and multimodal imaging analysis of CDs in cancer cells. After introducing diversified imaging functions, we focused on the design and the latest research progress of CDs in phototherapy and introduced in detail the strategies of CDs in phototherapy treatment and the challenges faced by clinical applications. We hope that this overview can provide important insights for researchers and accelerate the pace of research on CDs in imaging-guided phototherapy treatment.

Photodynamic Anti-Bacteria by Carbon Dots and Their Nano-Composites

The misuse of many types of broad-spectrum antibiotics leads to increased antimicrobial resistance. As a result, the development of a novel antibacterial agent is essential. Photodynamic antimicrobial chemotherapy (PACT) is becoming more popular due to its advantages in eliminating drug-resistant strains and providing broad-spectrum antibacterial resistance. Carbon dots (CDs), zero-dimensional nanomaterials with diameters smaller than 10 nm, offer a green and cost-effective alternative to PACT photosensitizers. This article reviewed the synthesis methods of antibacterial CDs as well as the recent progress of CDs and their nanocomposites in photodynamic sterilization, focusing on maximizing the bactericidal impact of CDs photosensitizers. This review establishes the base for future CDs development in the PACT field.

Copper(II)-Doped Carbon Dots as Catalyst for Ozone Degradation of Textile Dyes

A catalytic ozonation advanced oxidation process (AOP) with a copper(II)-doped carbon dot as catalyst, Cu-CD (using L-cysteine and polyethylene glycol (PEG) as precursors and passivation agents), was developed for textile wastewater treatment (T = 25 °C and pH = 7). Four dyes were analyzed—Methyl Orange (MO), Orange II sodium salt (O-II), Reactive Black 5 (RB-5) and Remazol Brilliant Blue R (RBB-R), as well as a real effluent from the dying and printing industry. The Cu-CD, with marked catalytic ozonation properties, was successfully synthesized by one-pot hydrothermal procedure with a size of 4.0 nm, a charge of −3.7 mV and a fluorescent quantum yield of 31%. The discoloration of the aqueous dye solutions followed an apparent first-order kinetics with the following rate constants (kap in min−1): MO, 0.210; O-II, 0.133; RB-5, 0.177; RBB-R, 0.086. In the presence of Cu-CD, the following apparent first-order rate constants were obtained (kapc in min−1) with the corresponding increase in the rate constant without catalyst (%Inc): MO, 1.184 (464%); O-II, 1.002 (653%); RB-5, 0.709 (301%); RBB-R, 0.230 (167%). The presence of sodium chloride (at a concentration of 50 g/L) resulted in a marked increase of the discoloration rate of the dye solution due to generation of other radicals, such as chlorine and chlorine oxide, resulting from the reaction of ozone and chloride. Taking into consideration that the real textile effluent under research has a high carbonate concentration (>356 mg/L), which inhibits ozone decomposition, the discoloration first-order rate constants without and with Cu-CD (kap = 0.0097 min−1 and kapc = 0.012 min−1 (%Inc = 24%), respectively) were relatively small. Apparently, the Cu-CD, the surface of which is covered by a soft and highly hydrated caramelized PEG coating, accelerates the ozone decomposition and dye adsorption, increasing its degradation.

A self-assembled nanoplatform based on Ag2S quantum dots and tellurium nanorods for combined chemo-photothermal therapy guided by H2O2-activated near-infrared-II fluorescence imaging

A nanoplatform based on Ag₂S quantum dots (QDs) and tellurium nanorods (TeNRs) was developed for combined chemo-photothermal therapy guided by H₂O₂-activated near-infrared (NIR)-II fluorescence imaging. Polypeptide PC₁₀AGRD-modified TeNRs and Ag₂S QDs were co-encapsulated in 4T1 cell membrane to prepare a nanoplatform (CCM@AT). Ag₂S QDs and TeNRs in the CCM@AT were used as a fluorescence probe and photosensitizer, and a chemotherapeutic prodrug and quenching agent to quench the fluorescence of Ag₂S QDs, respectively. After the CCM@AT was specifically targeted to the tumor site, the TeNRs were dissolved by the high concentration of H₂O₂ at the tumor site to light up the fluorescence of Ag₂S QDs for NIR-II fluorescence imaging. In addition, the generated toxic TeO₆^6- molecules decreased ATP production by selective cancer chemotherapy, which is beneficial for photothermal therapy. The elevated temperature due to photothermal therapy in turn promoted the chemical reaction in chemotherapy. In vitro and in vivo toxicity results showed that the CCM@AT possesses high biocompatibility. Compared to single photothermal therapy and chemotherapy, the synergistic chemo-photothermal therapy can effectively suppress the growth of 4T1 tumor. This all-in-one nanoplatform provides a boulevard for the combination therapy of tumors guided by NIR-II fluorescence imaging. STATEMENT OF SIGNIFICANCE: NIR-II fluorescence imaging shows the characteristics of low tissue absorption, reflection, and scattering, which can greatly reduce the influence of autofluorescence in vivo. However, the non-negligible effect of autofluorescence is still observed in fluorescence imaging in vivo. Therefore, there is an urgent need to develop a strategy of controlled release of fluorescence for accurate imaging and tumor therapy. Here, Ag₂S quantum dots (QDs) with NIR-II fluorescence emission and good photothermal conversion efficiency are used as a fluorescence probe and photosensitizer, and tellurium nanorods (TeNRs) are used as a chemotherapeutic prodrug and quenching agent to quench the fluorescence of Ag₂S QDs. This multiple nanoplatform provides an inspiration for the combination therapy of tumor guided by NIR-II fluorescence imaging.

F,N-Doped carbon dots as efficient Type I photosensitizers for photodynamic therapy

Photodynamic therapy (PDT) is a promising and emerging method for the treatment of cancer. Usually, Type II PDT is used in the clinic, and mainly involves three key elements: a photosensitizer, molecular oxygen and laser light. However, it is known that tumor tissue is deficient in oxygen molecules which is why Type I PDT is mostly preferred in the therapy of tumors in which the hypoxic tissue plays a major role. Fluorescent carbon dots (CDs) have shown great potential in cancer theranostics, acting as bioimaging agents and photosensitizers. Herein, we have synthesized novel kinds of fluorine and nitrogen co-doped carbon dots (F,NCDs) that emit bright green fluorescence under ultra-violet light. The F,NCDs have excellent water solubility and low cytotoxicity. They can generate hydroxyl radicals (˙OH) and superoxide anions (˙O₂^-) under LED light (400-500 nm, 15 mW cm^-2) irradiation, making them ideal photosensitizers for Type I PDT. Furthermore, upon using the HepG2 cell line as an in vitro model, the F,NCDs exhibit a better cell imaging effect and higher PDT efficiency than the control sample of CDs without F and N doping. This work has illustrated that the F,NCDs are promising in achieving the image-guided PDT of cancers, usually in a hypoxia tumor microenvironment.

Engineered Nanostructured Photocatalysts for Cancer Therapy

The present review aims at highlighting recent advances in the development of photocatalysts devoted to cancer therapy applications. We pay especial attention to the engineering aspects of different nanomaterials including inorganic semiconductors, organic-based nanostructures, noble metal-based systems or synergistic hybrid heterostructures. Furthermore, we also explore and correlate structural and optical properties with their photocatalytic capability to successfully performing in cancer-related therapies. We have made an especial emphasis to introduce current alternatives to organic photosensitizers (PSs) in photodynamic therapy (PDT), where the effective generation of reactive oxidative species (ROS) is pivotal to boost the efficacy of the treatment. We also overview current efforts in other photocatalytic strategies to tackle cancer based on photothermal treatment, starvation therapy, oxidative stress unbalance via glutathione (GSH) depletion, biorthogonal catalysis or local relief of hypoxic conditions in tumor microenvironments (TME).

Red-emitting carbon nanoparticles with unprecedented singlet oxygen generation efficiency for cancer theranostics

Fluorescent Red-emitting carbon nanoparticles (RCNPs) are produced by an economical and green hydrothermal method using Eucalyptus leaves as a precursor. This is the first report of its kind demonstrating RCNPs in combined PDT-Chemo combination therapy, as RCNPs bind with mitoxantrone (MTO) electrostatically. The synthesized RCNPs before and after conjugation of MTO are characterised using DLS, SEM, TEM, UV-Vis, Fluorescence, FTIR, and ¹H NMR Spectroscopy. FTIR and ¹H NMR confirm the interaction between -NH proton of MTO with carboxylic acid oxygen of RCNPs. RCNPs are demonstrated as brightly fluorescent, type II photosensitizer (PS) with an extraordinary ¹O₂ quantum yield of 0.96, when triggered with a red laser at 660 nm. Moreover, the biocompatibility of RCNPs and RCNPs-MTO are examined and confirmed by performing a cytotoxicity assay on MCF-7 cell lines. Subsequently, to explore the internalization process of the RCNPs as a function of concentration, confocal imaging study is also carried out. The cell viability and the apoptosis assay indicates that RCNPs-MTO can achieve the PDT-Chemo synergistic cancer therapy. To the best of our knowledge, this is the first time that Eucalyptus leaves, a natural source of great abundance, is used as raw material and applied for combined PDT-chemotherapy.

One-step hydrothermal synthesis of nitrogen-doped carbon dots as a super selective and sensitive probe for sensing metronidazole in multiple samples

A reliable, super selective and sensitive nitrogen-doped carbon dots (N-CDs) nanoprobe that can quantitatively and quickly detect the concentration of metronidazole (MTZ) in multiple samples was built. We first prepared the N-CDs using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC·HCl) as the precursor via a green, facile one-step hydrothermal method. The as-synthesized N-CDs were characterized by a variety of analytical and spectroscopic techniques, which revealed excitation-dependent fluorescence behavior with the maximum excitation and emission wavelengths being 335 and 370 nm, respectively. Significantly, the fluorescence emission of N-CDs underwent initial quenching upon the addition of MTZ via the inner filter effect (IFE), indicating a prospective detection method for MTZ. The linear range for MTZ detection was 0.1-250 μM, and the corresponding limit of detection (LOD) and limit of quantification (LOQ) were calculated to be only 70 nM and 233.33 nM, respectively. Moreover, due to the negligible cytotoxicity and superior biocompatibility, the fabricated N-CDs show a promising prospect for detecting MTZ in living cells. In general, our proposed N-CDs-based fluorescence sensing platform possesses super low LOD and LOQ values, wide linear range, and satisfactory selectivity, and can be applied to the detection of MTZ in multiple real samples.

Research Progress in the Synthesis of Targeting Organelle Carbon Dots and Their Applications in Cancer Diagnosis and Treatment

With increasing knowledge about diseases at the histological, cytological to sub-organelle level, targeting organelle therapy has gradually been envisioned as an approach to overcome the shortcomings of poor specificity and multiple toxic side effects on tissues and cell-level treatments using the currently available therapy. Organelle carbon dots (CDs) are a class of functionalized CDs that can target organelles. CDs can be prepared by a "synchronous in situ synthesis method" and "asynchronous modification method." The superior optical properties and good biocompatibility of CDs can be preserved, and they can be used as targeting particles to carry drugs into cells while reducing leakage during transport. Given the excellent organelle fluorescence imaging properties, targeting organelle CDs can be used to monitor the physiological metabolism of organelles and progression of human diseases, which will provide advanced understanding and accurate diagnosis and targeted treatment of cancers. This study reviews the methods used for preparation of targeting organelle CDs, mechanisms of accurate diagnosis and targeted treatment of cancer, as well as their application in the area of cancer diagnosis and treatment research. Finally, the current difficulties and prospects for targeting organelle CDs are prospected.

Carbon Dots: Classification, Properties, Synthesis, Characterization, and Applications in Health Care-An Updated Review (2018-2021)

Carbon dots (CDs) are usually smaller than 10 nm in size, and are meticulously formulated and recently introduced nanomaterials, among the other types of carbon-based nanomaterials. They have gained significant attention and an incredible interest in the field of nanotechnology and biomedical science, which is merely due to their considerable and exclusive attributes; including their enhanced electron transferability, photobleaching and photo-blinking effects, high photoluminescent quantum yield, fluorescence property, resistance to photo-decomposition, increased electrocatalytic activity, good aqueous solubility, excellent biocompatibility, long-term chemical stability, cost-effectiveness, negligible toxicity, and acquaintance of large effective surface area-to-volume ratio. CDs can be readily functionalized owing to the abundant functional groups on their surfaces, and they also exhibit remarkable sensing features such as specific, selective, and multiplex detectability. In addition, the physico-chemical characteristics of CDs can be easily tunable based on their intended usage or application. In this comprehensive review article, we mainly discuss the classification of CDs, their ideal properties, their general synthesis approaches, and primary characterization techniques. More importantly, we update the readers about the recent trends of CDs in health care applications (viz., their substantial and prominent role in the area of electrochemical and optical biosensing, bioimaging, drug/gene delivery, as well as in photodynamic/photothermal therapy).

Advances in chlorin-based photodynamic therapy with nanoparticle delivery system for cancer treatment

Introduction: The treatment of tumors is one of the most difficult problems in the medical field at present. Patients often use a comprehensive therapy that combines surgery, radiotherapy, and chemotherapy. Photodynamic therapy (PDT) has prominent potential for eradicating various cancers. Chlorin-based photosensitizers (PSs), as one of the most utilized photosensitizers, have many advantages over conventional photosensitizers; however, a successful chlorin-based PDT needs multi-functional nano-carriers for selective photosensitizer delivery. The number of researches about nanoparticles designed for improved chlorin-based PSs is increasing in the current era. In this article, we give a brief review focused on the recent research progress in design of chlorin-based nanoparticles for the treatment of malignant tumors with photodynamic therapy.Areas covered: This review focuses on the current nanoparticle platforms for PDT, and describes different strategies to achieve controllable PDT by chlorin-nano-delivery systems. The challenges and prospects of PDT in clinical applications are also discussed.Expert opinions: The requirement for PDT to eradicate cancers has increased exponentially in recent years. The major clinically used photosensitizers are hydrophobic. The main obstacles in effective delivery of PSs are associated with this intrinsic nature. The design of nano-delivery systems to load PSs is pivotal for PSs' widespread use.

Doped-carbon dots: Recent advances in their biosensing, bioimaging and therapy applications

As a fascinating class of fluorescent carbon dots (CDs), doped-CDs are now sparked intense research interest, particularly in the diverse fields of biomedical applications due to their unique advantages, including low toxicity, physicochemical, photostability, excellent biocompatibility, and so on. In this review, we have summarized the most recent developments in the literature regarding the employment of doped-CDs for pharmaceutical and medical applications, which are published over approximately the past five years. Accordingly, we discuss the toxicity and optical properties of these nanomaterials. Beyond the presentation of successful examples of the application of these multifunctional nanoparticles in photothermal therapy, photodynamic therapy, and antibacterial activity, we further highlight their application in the cellular labeling, dual imaging, and in vitro and in vivo bioimaging by use of fluorescent-, photoacoustic-, magnetic-, and computed tomography (CT)-imaging. The potency of doped-CDs was also described in the biosensing of ions, small molecules, and drugs in biological samples or inside the cells. Finally, the advantages, disadvantages, and common limitations of doped-CD technologies are reviewed, along with the future prospects in biomedical research. Therefore, this review provides a concise insight into the current developments and challenges in the field of doped-CDs, especially for biological and biomedical researchers.

Recoverable peroxidase-like Fe3O4@MoS2-Ag nanozyme with enhanced antibacterial ability

Antibacterial agents with enzyme-like properties and bacteria-binding ability have provided an alternative method to efficiently disinfect drug-resistance microorganism. Herein, a Fe₃O₄@MoS₂-Ag nanozyme with defect-rich rough surface was constructed by a simple hydrothermal method and in-situ photodeposition of Ag nanoparticles. The nanozyme exhibited good antibacterial performance against E. coli (~69.4%) by the generated ROS and released Ag⁺, while the nanozyme could further achieve an excellent synergistic disinfection (~100%) by combining with the near-infrared photothermal property of Fe₃O₄@MoS₂-Ag. The antibacterial mechanism study showed that the antibacterial process was determined by the collaborative work of peroxidase-like activity, photothermal effect and leakage of Ag⁺. The defect-rich rough surface of MoS₂ layers facilitated the capture of bacteria, which enhanced the accurate and rapid attack of •OH and Ag⁺ to the membrane of E. coli with the assistance of local hyperthermia. This method showed broad-spectrum antibacterial performance against Gram-negative bacteria, Gram-positive bacteria, drug-resistant bacteria and fungal bacteria. Meanwhile, the magnetism of Fe₃O₄ was used to recycle the nanozyme. This work showed great potential of engineered nanozymes for efficient disinfection treatment.