Light-triggered theranostics based on photosensitizer-conjugated carbon dots for simultaneous enhanced-fluorescence imaging and photodynamic therapy

Biocompatible fluorescent carbon nanoparticles as nanocarriers for targeted delivery of tamoxifen for regression of Breast carcinoma

Breast cancer (BC) is the most common malignancy among females worldwide, and its high metastasis rates are the leading cause of death just after lung cancer. Currently, tamoxifen (TAM) is a hydrophobic anticancer agent and a selective estrogen modulator (SERM), approved by the FDA that has shown potential anticancer activity against BC, but the non-targeted delivery has serious side effects that limit its ubiquitous utility. Therefore, releasing anti-cancer drugs precisely to the tumor site can improve efficacy and reduce the side effects on the body. Nanotechnology has emerged as one of the most important strategies to solve the issue of overdose TAM toxicity, owing to the ability of nano-enabled formulations to deliver desirable quantity of TAM to cancer cells over a longer period of time. In view of this, use of fluorescent carbon nanoparticles in targeted drug delivery holds novel promise for improving the efficacy, safety, and specificity of TAM therapy. Here, we synthesized biocompatible carbon nanoparticles (CNPs) using chitosan molecules without any toxic surface passivating agent. Synthesized CNPs exhibit good water dispersibility and emit intense blue fluorescence upon excitation (360 nm source). The surface of the CNPs has been functionalized with folate using click chemistry to improve the targeted drug uptake by the malignant cell. The pH difference between cancer and normal cells was successfully exploited to trigger TAM release at the target site. After six hours of incubation, CNPs released ∼ 74 % of the TAM drug in acidic pH. In vitro, studies have also demonstrated that after treatment with the synthesized CNPs, significant inhibition of the tumor growth could be achieved.

Fluorescent carbon dots for sensing applications: a review

Luminescent carbon dots (CDs) are important class of nanomaterials with fantastic photoluminescence (PL) properties, great biocompatibility, extraordinary solubility in water, minimal expense, and so on. There are many methods for their preparation and they are mainly classed into two groups, top-down and bottom-up approaches. In order to understand the origin of fluorescence in quantum CDs, three mechanisms have been proposed namely molecular state, surface state, and quantum confinement phenomenon. Fluorescent CDs have significant application in the fields of biochemical sensing, photocatalysis, bioimaging, delivery of drugs, and other related fields. In this review article the application of quantum dots as detecting component, for the sensing of different targets, has been summed up. In fact, the detection of several analytes including, anions, cations, small molecules, polymers, cells, and microscopic organisms has been discoursed. Moreover, the future aspects of CDs as detecting resources have been explored.

Carbon Dots in the Pathological Microenvironment: ROS Producers or Scavengers?

Reactive oxygen species (ROS), as metabolic byproducts, play pivotal role in physiological and pathological processes. Recently, studies on the regulation of ROS levels for disease treatments have attracted extensive attention, mainly involving the ROS-induced toxicity therapy mediated by ROS producers and antioxidant therapy by ROS scavengers. Nanotechnology advancements have led to the development of numerous nanomaterials with ROS-modulating capabilities, among which carbon dots (CDs) standing out as noteworthy ROS-modulating nanomedicines own their distinctive physicochemical properties, high stability, and excellent biocompatibility. Despite progress in treating ROS-related diseases based on CDs, critical issues such as rational design principles for their regulation remain underexplored. The primary cause of these issues may stem from the intricate amalgamation of core structure, defects, and surface states, inherent to CDs, which poses challenges in establishing a consistent generalization. This review succinctly summarizes the recently progress of ROS-modulated approaches using CDs in disease treatment. Specifically, it investigates established therapeutic strategies based on CDs-regulated ROS, emphasizing the interplay between intrinsic structure and ROS generation or scavenging ability. The conclusion raises several unresolved key scientific issues and prominent technological bottlenecks, and explores future perspectives for the comprehensive development of CDs-based ROS-modulating therapy.

Advancements in the synthesis of carbon dots and their application in biomedicine

As a sort of fluorescent carbon nanomaterial with a particle size of less than 10 nm, carbon dots (CDs) have their own merits of good dispersibility in water, stable optical properties, strong chemical inertness, stable optical properties, and good biosecurity. These excellent peculiarities facilitated them like sensing, imaging, medicine, catalysis, and optoelectronics, making them a new star in the field of nanotechnology. In particular, the development of CDs in the fields of chemical probes, imaging, cancer therapy, antibacterial and drug delivery has become a hot topic in current research. Although the biomedical applications in CDs have been demonstrated in many research articles, a systematic summary of their role in biomedical applications is scarce. In this review, we introduced the basic information of CDs in detail, including synthesis approaches of CDs as well as their favorable properties including photoluminescence and low cytotoxicity. Subsequently, the application of CDs in the field of biomedicine was emphasized. Finally, the main challenges and research prospects of CDs in this field were proposed, which might provide some detailed information in designing new CDs in this promising biomedical field.

Double-layer hollow mesoporous silica nanoparticles for ultrasound-guided photodynamic treatment

Cervical carcinoma persists as a major global public health burden. While conventional therapeutic modalities inevitably cause ablation of adjacent non-tumorous tissues, photodynamic therapy (PDT) offers a targeted cytotoxic strategy through a photosensitizing agent (PS). However, the hydrophobicity and lack of selective accumulation of promising PS compounds such as zinc(II) phthalocyanine (ZnPc) impedes their clinical translation as standalone agents. The present study sought to incorporate ZnPc within double-layer hollow mesoporous silica nanoparticles (DHMSN) as nanocarriers to enhance aqueous dispersibility and tumor specificity. Owing to their compartmentalized design, the hollow mesoporous silica nanoparticles (HMSN) demonstrated enhanced ultrasonic imaging contrast. Combined with the vaporization of the perfluorocarbon perfluoropentane (PFP), the HMSN-encapsulated ZnPc enabled real-time ultrasound monitoring of PDT treatment.In vivo, the innate thermal energy induced vaporization of the DHMSN-carried PFP to significantly amplify ultrasound signals from the tumor site. Results demonstrated biocompatibility, efficient PFP microbubble generation, and robust photocatalytic activity. Collectively, this investigation establishes ultrasound-guided PDT utilizing multi-layer HMSN as a targeted therapeutic strategy for cervical malignancies with mitigated toxicity.

The applications of carbon dots in oral health: A scoping review

OBJECTIVES

This scoping review aims to provide an overview of the research and potential applications of carbon dots (CDs) for oral health purposes.

DESIGN

Systematic literature searches were performed on PubMed and Web of Science databases (up to February 2023). Two co-authors selected the published works independently and extracted the data in accordance with the PRISMA statement. Studies with the application of CDs for oral health purposes were included.

RESULTS

Among 152 articles, 19 articles were finally selected. Eight studies investigated the anti-microbial effects of CDs against, for example, oral pathogens, eight studies explored the applicability of CDs in relation to oral cancer, and three studies investigated CDs in relation to cell differentiation and tissue regeneration in oral health. The studies showed the promising potential of CDs in oral health, particularly for inducing bacterial killing by increasing reactive oxygen species, killing oral cancer cells via photodynamic therapeutic effects, and inducing dental pulp and periodontal bone regeneration.

CONCLUSION

The findings show that CDs have the potential to be utilized in the future for various oral health purposes. Besides, these results underline the broad-spectrum applicability of CDs, crossing the borders of oral health.

Carbon dots as a novel photosensitizer for photodynamic therapy of cancer and bacterial infectious diseases: recent advances

Carbon dots (CDs) are novel carbon-based nanomaterials that have been used as photosensitizer-mediated photodynamic therapy (PDT) in recent years due to their good photosensitizing activity. Photosensitizers (PSs) are main components of PDT that can produce large amounts of reactive oxygen species (ROS) when stimulated by light source, which have the advantages of low drug resistance and high therapeutic efficiency. CDs can generate ROS efficiently under irradiation and therefore have been extensively studied in disease local phototherapy. In tumor therapy, CDs can be used as PSs or PS carriers to participate in PDT and play an extremely important role. In bacterial infectious diseases, CDs exhibit high bactericidal activity as CDs are effective in disrupting bacterial cell membranes leading to bacterial death upon photoactivation. We focus on recent advances in the therapy of cancer and bacteria with CDs, and also briefly summarize the mechanisms and requirements for PSs in PDT of cancer, bacteria and other diseases. We also discuss the role CDs play in combination therapy and the potential for future applications against other pathogens.

Photo-Controlled Reversible Uptake and Release of a Modified Sulfamethoxazole Antibiotic Drug from a Pillar[5]arene Cross-Linked Gelatin Hydrogel

Pillararene cross-linked gelatin hydrogels were designed and synthesized to control the uptake and release of antibiotics using light. A suite of characterization techniques ranging from spectroscopy (FT-IR, 1H and 13C NMR, and MAS NMR), X-ray crystallographic analysis, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) was employed to investigate the physicochemical properties of hydrogels. The azobenzene-modified sulfamethoxazole (Azo-SMX) antibiotic was noncovalently incorporated into the hydrogel via supramolecular host-guest interactions to afford the A-hydrogel. While in its ground state, the Azo-SMX guest has a trans configuration structure and forms a thermodynamically stable inclusion complex with the pillar[5]arene motif in the hydrogel matrix. When the A-hydrogel was exposed to 365 nm UV light, Azo-SMX underwent a photoisomerization reaction. This changed the structure of Azo-SMX from trans to cis, and the material was released into the environment. The Azo-SMX released from the hydrogel was effective against both Gram-positive and Gram-negative bacteria. Importantly, the A-hydrogel exhibited a striking difference in antibacterial activity when applied to bacterial colonies in the presence and absence of UV light, highlighting the switchable antibacterial activity of A-hydrogel aided by light. In addition, all hydrogels containing pillar[5]arenes have demonstrated biocompatibility and effectiveness as scaffolds for biological and medical purposes.

A fast hemostatic and enhanced photodynamic 2-dimensional metal-organic framework loaded aerogel patch for wound management

Achieving rapid hemostasis and highly effective antibacterial holds significant importance in the early-stage treatment of wounds. In this study, a hybrid aerogel patch comprising carbon quantum dots (CQDs) modified 2-dimensional (2D) porphyrinic metal-organic framework (MOF) nanosheets was designed by incorporating gelatin methacrylate (GelMA) and polyacrylamide (PAM) based matrix. On one hand, CQDs were stably doped onto the surface of the 2D MOF nanosheets, thereby enhancing the photodynamic activity through fluorescence resonance energy transfer (FRET) process. After the preparation of hybrid aerogel patch, the patch loaded with CQDs-doped 2D MOF exhibited excellent photodynamic bactericidal activity against Gram-positive Staphylococcus aureus (>99.99 %) and Gram-negative Escherichia coli (>99.99 %). On the other hand, the hybrid patch with highly porous and absorbent structure can rapidly absorb blood to aggregate clotting components and form a hydration barrier covering the wound to enhance hemostasis. Besides, the hemolysis and cytotoxicity assays demonstrated a good biocompatibility of this designed patch. In summary, this 2D MOF-loaded aerogel patch holds a potential to achieve rapid hemostasis and effective anti-infection in the early-stage treatment of traumatic wounds.

Cell-Derived N/P/S-Codoped Fluorescent Carbon Nanodots with Intrinsic Targeting Ability for Tumor-Specific Phototheranostics

Combining targeting ability, imaging function, and photothermal/photodynamic therapy into a single agent is highly desired for cancer theranostics. Herein, we developed a one-for-all nanoplatform with N/P/S-codoped fluorescent carbon nanodots (CNDs) for tumor-specific phototheranostics. The CNDs were prepared via a one-pot hydrothermal process using cancer cells as sources of carbon, nitrogen, phosphorus, and sulfur. The obtained N/P/S-codoped CNDs exhibit wide light absorption in the range of 200-900 nm and excitation-dependent emission with high photostability. Importantly, the cancer cell-derived N/P/S-codoped CNDs have outstanding biocompatibility and naturally intrinsic targeted ability for cancer cells as well as dual photothermal/photodynamic effects under 795 nm laser irradiation. Moreover, the photothermal conversion efficiency and singlet oxygen (1O2) generation efficiency were calculated to be 52 and 34%, respectively. These exceptional properties enable CNDs to act as fine theranostic agents for targeted imaging and photothermal-photodynamic synergistic therapy within the NIR therapeutic window. The CNDs prepared in this work are promising for construction as a universal tumor phototheranostic platform.

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.

Targeted therapy of breast tumor by PLGA-based nanostructures: The versatile function in doxorubicin delivery

Breast carcinoma is a molecularly diverse illness, and it is among the most prominent and often reported malignancies in female across the globe. Surgical intervention, chemotherapy, immunotherapy, gene therapy, and endocrine treatment are among the currently viable treatment options for the carcinoma of breast. Chemotherapy is among the most prevalent cancer management strategy. Doxorubicin (DOX) widely employed as a cytostatic medication for the treatment of a variety of malignancies. Despite its widespread acceptance and excellent efficacy against an extensive line up of neoplasia, it has a variety of shortcomings that limit its therapeutic potential in the previously mentioned indications. Employment of nanoparticulate systems has come up as a unique chemo medication delivery strategy and are being considerably explored for the amelioration of breast carcinoma. Polylactic-co-glycolic acid (PLGA)-based nano systems are being utilized in a number of areas within the medical research and medication delivery constitutes one of the primary functions for PLGA given their inherent physiochemical attributes, including their aqueous solubility, biocompatibility, biodegradability, versatility in formulation, and limited toxicity. Herein along with the different application of PLGA-based nano formulations in cancer therapy, the present review intends to describe the various research investigations that have been conducted to enumerate the effectiveness of DOX-encapsulated PLGA nanoparticles (DOX-PLGA NPs) as a feasible treatment option for breast cancer.

The development of ZnO nanoparticle-embedded graphitic-carbon nitride towards triple-negative breast cancer therapy

The present study deals with the effects of curcumin-loaded ZnO nanoparticles (NPs) embedded in graphitic-carbon nitride (g-C3N4) sheets for breast cancer cells. The synthesis of these sheets was carried out by a simple co-precipitation method. The physicochemical and thermal properties of the composite sheets were studied using various characterization techniques. The powder X-ray diffraction and high-resolution transmission electron microscopy analyses confirmed the hexagonal wurtzite phase of the ZnO nanoparticles, which were randomly distributed on the g-C3N4 nanosheets, generating a finely bonded interface between the two components. The X-ray photoelectron spectroscopy analysis confirmed the successful formation of the g-C3N4@ZnO composite, while the thermal studies revealed the thermal stability of the composite. In addition, the drug release and kinetics studies proved that the release of curcumin was more significant under acidic conditions (pH 5) compared with neutral pH (7.4). Further, the biological assays verified the antibacterial activity (against two different cultures of E. coli and S. aureus) and anticancer activity (against MDA-MB-231 cancer cells) of the g-C3N4@ZnO/C nanocomposite. Finally, the lactate dehydrogenase activity assay presented the cytotoxic assessment of the nanocomposite based on its cytoplasmic activity and the extent of enzymes released from the damaged cells.

Mitochondria-Targeting Upconversion Nanoparticles@MOF for Multiple-Enhanced Photodynamic Therapy in Hypoxic Tumor

The effect of photodynamic therapy (PDT) is severely limited by tumor hypoxia and the short half-life of reactive oxygen species (ROS). Herein, we constructed a near-infrared (NIR) light-regulated PDT nanoplatform (TPP-UCNPs@MOF-Pt) consisting of an upconversion nanoparticle (UCNP) core and porphyrin-based metal-organic framework (MOF) shell with platinum nanoparticles (PtNPs) and a mitochondria-targeting triphenylphosphine (TPP) group on the surface. TPP-UCNPs@MOF-Pt could effectively relieve the tumor hypoxia by converting intracellular H₂O₂ to oxygen (O₂) and elevated the ROS level to enhance PDT efficacy under NIR light irradiation. In addition, the mitochondria-targeting TPP-UCNPs@MOF-Pt was localized on the mitochondria, leading to severe depolarization of the mitochondrial membrane and activation of the apoptotic pathway, further amplifying the therapeutic efficacy. In vitro and in vivo experiments demonstrated that the greatly enhanced photodynamic therapeutic efficacy of TPP-UCNPs@MOF-Pt was achieved by combining relief of tumor hypoxia with mitochondrial targeting and NIR activation. This study provides a promising strategy for construction of an MOF-based multifunctional nanoplatform to address the current limitations of PDT treatment for hypoxic tumors.

Artificial intelligence in theranostics of gastric cancer, a review

Gastric cancer (GC) is one of the commonest cancers with high morbidity and mortality in the world. How to realize precise diagnosis and therapy of GC owns great clinical requirement. In recent years, artificial intelligence (AI) has been actively explored to apply to early diagnosis and treatment and prognosis of gastric carcinoma. Herein, we review recent advance of AI in early screening, diagnosis, therapy and prognosis of stomach carcinoma. Especially AI combined with breath screening early GC system improved 97.4 % of early GC diagnosis ratio, AI model on stomach cancer diagnosis system of saliva biomarkers obtained an overall accuracy of 97.18 %, specificity of 97.44 %, and sensitivity of 96.88 %. We also discuss concept, issues, approaches and challenges of AI applied in stomach cancer. This review provides a comprehensive view and roadmap for readers working in this field, with the aim of pushing application of AI in theranostics of stomach cancer to increase the early discovery ratio and curative ratio of GC patients.

Renal Clearable Quantum Dot-Drug Conjugates Modulate Labile Iron Species and Scavenge Free Radicals for Attenuating Chemotherapeutic Drug-Induced Acute Kidney Injury

Chemotherapeutic drug-induced acute kidney injury (AKI) involves pathologically increased labile iron species in the kidneys that mediate the excessive generation of reactive oxygen species (ROS) to induce ferroptosis and apoptosis, subsequently driving renal dysfunction. Herein, we report renal clearable quantum dot-drug conjugates (QDCs) composed of carbon quantum dot (CDs), deferoxamine (DFO), and poly(ethylene glycol) (PEG) for attenuating chemotherapeutic drug-induced AKI. The CDs component in QDCs can not only provide DFO with high renal specificity to effectively remove the pathological labile iron species in the kidneys to block the source of ROS generation but also exert high antioxidative effects to avoid renal oxidative damage caused by the ROS that have been overproduced. In cisplatin-induced AKI mice, QDCs can inhibit ferroptosis and apoptosis with high efficacy for AKI treatment. This study will provide a new paradigm to realize enhanced therapeutic efficacy for AKI by simultaneously removing the pathological labile iron species and eliminating overproduced ROS in the kidneys to achieve the goal of addressing both symptoms and root causes.

Boron Dopants in Red-Emitting B and N Co-Doped Carbon Quantum Dots Enable Targeted Imaging of Lysosomes

Lysosomes are of great significance to cell growth, metabolism, and survival, as they independently maintain acidity and regulate various balances in cells. Therefore, it is essential to develop advanced probes for lysosome visualization and live tracking. Herein, a type of lysosome-targeting probe based on boron (B) and nitrogen (N) co-doped carbon quantum dots (B/N-CQDs) is presented, which exhibits red emission at 618 nm, high quantum yield (28%), and excellent fluorescence stability (97% at 1 h). These B/N-CQDs are prepared by a novel and green solid-state reaction and purified using a simple extraction process without additional chemical modifications. It is found that the boron dopants in the structure play a crucial role in the resultant lysosome-specific targeting property through borate esterification between boronic acid groups in the sample and diol structures in glycoproteins. This can be applied as a powerful tool for cell apoptosis, necrosis, and endosomal escape tracking. This work not only offers a new concept for targeted subcellular probe designs via chemical doping but also demonstrates the feasibility of these tools for analyzing complex cellular physiological activities.

Multifunctional Carbon-Based Nanoparticles: Theranostic Applications in Cancer Therapy and Diagnosis

Cancer diagnosis and treatment are the most critical challenges in modern medicine. Conventional cancer treatments no longer meet the needs of the health field due to the high rate of mutations and epigenetic factors that have caused drug resistance in tumor cells. Hence, the search for unique methods and factors is quickly expanding. The development of nanotechnology in medicine and the search for a system to integrate treatment and diagnosis to achieve an effective approach to overcome the known limitations of conventional treatment methods have led to the emergence of theranostic nanoparticles and nanosystems based on these nanoparticles. An influential group of these nanoparticles is carbon-based theranostic nanoparticles. These nanoparticles have received significant attention due to their unique properties, such as electrical conductivity, high strength, excellent surface chemistry, and wide range of structural diversity (graphene, nanodiamond, carbon quantum dots, fullerenes, carbon nanotubes, and carbon nanohorns). These nanoparticles were widely used in various fields, such as tissue engineering, drug delivery, imaging, and biosensors. In this review, we discuss in detail the recent features and advances in carbon-based theranostic nanoparticles and the advanced and diverse strategies used to treat diseases with these nanoparticles.

BioMOF-Based Anti-Cancer Drug Delivery Systems

A variety of nanomaterials have been developed specifically for biomedical applications, such as drug delivery in cancer treatment. These materials involve both synthetic and natural nanoparticles and nanofibers of varying dimensions. The efficacy of a drug delivery system (DDS) depends on its biocompatibility, intrinsic high surface area, high interconnected porosity, and chemical functionality. Recent advances in metal-organic framework (MOF) nanostructures have led to the achievement of these desirable features. MOFs consist of metal ions and organic linkers that are assembled in different geometries and can be produced in 0, 1, 2, or 3 dimensions. The defining features of MOFs are their outstanding surface area, interconnected porosity, and variable chemical functionality, which enable an endless range of modalities for loading drugs into their hierarchical structures. MOFs, coupled with biocompatibility requisites, are now regarded as highly successful DDSs for the treatment of diverse diseases. This review aims to present the development and applications of DDSs based on chemically-functionalized MOF nanostructures in the context of cancer treatment. A concise overview of the structure, synthesis, and mode of action of MOF-DDS is provided.

Fe-Doped Carbon Dots as NIR-II Fluorescence Probe for In Vivo Gastric Imaging and pH Detection

Carbon dots (CDs) with excellent cytocompatibility, tunable optical properties, and simple synthesis routes are highly desirable for use in optical bioimaging. However, the majority of existing CDs are triggered by ultraviolet/blue light, presenting emissions in the visible/first near-infrared (NIR-I) regions, which do not allow deep tissue penetration. Emerging research into CDs with NIR-II emission in the red region has generated limited designs with poor quantum yield, restricting their in vivo imaging applications due to low penetration depth. Developing novel CDs with NIR-II emissions and high quantum yield has significant and far-reaching applications in bioimaging and photodynamic therapy. Here, it is developed for the first time Fe-doped CDs (Fe-CDs) exhibiting the excellent linear relationship between 900-1200 nm fluorescence-emission and pH values, and high quantum yield (QY-1.27%), which can be used as effective probes for in vivo NIR-II bioimaging. These findings demonstrate reliable imaging accuracy in tissue as deep as 4 mm, reflecting real-time pH changes comparable to a standard pH electrode. As an important example application, the Fe-CDs probe can non-invasively monitor in vivo gastric pH changes during the digestion process in mice, illustrating its potential applications in aiding imaging-guided diagnosis of gastric diseases or therapeutic delivery.

Covalent organic framework nanomedicines: Biocompatibility for advanced nanocarriers and cancer theranostics applications

Nanomedicines for drug delivery and imaging-guided cancer therapy is a rapidly growing research area. The unique properties of nanomedicines have a massive potential in solving longstanding challenges of existing cancer drugs, such as poor localization at the tumor site, high drug doses and toxicity, recurrence, and poor immune response. However, inadequate biocompatibility restricts their potential in clinical translation. Therefore, advanced nanomaterials with high biocompatibility and enhanced therapeutic efficiency are highly desired to fast-track the clinical translation of nanomedicines. Intrinsic properties of nanoscale covalent organic frameworks (nCOFs), such as suitable size, modular pore geometry and porosity, and straightforward post-synthetic modification via simple organic transformations, make them incredibly attractive for future nanomedicines. The ability of COFs to disintegrate in a slightly acidic tumor microenvironment also gives them a competitive advantage in targeted delivery. This review summarizes recently published applications of COFs in drug delivery, photo-immuno therapy, sonodynamic therapy, photothermal therapy, chemotherapy, pyroptosis, and combination therapy. Herein we mainly focused on modifications of COFs to enhance their biocompatibility, efficacy and potential clinical translation. This review will provide the fundamental knowledge in designing biocompatible nCOFs-based nanomedicines and will help in the rapid development of cancer drug carriers and theranostics.

Recent advances in carbon dots: synthesis and applications in bone tissue engineering

Bone tissue engineering (BTE), based on the perfect combination of seed cells, scaffold materials and growth factors, has shown unparalleled potential in the treatment of bone defects and related diseases. As the site of cell attachment, proliferation and differentiation, scaffolds composed of biomaterials play a crucial role in BTE. Over the past years, carbon dots (CDs), a new type of carbon-based nanomaterial, have attracted extensive research attention due to their good biocompatibility, unique optical properties, and abundant functional groups. This paper reviews recent research progress in the use of CDs in the field of BTE. Firstly, different preparation methods of CDs are summarized. Then, the properties and categories of CDs applied in BTE are described in detail. Subsequently, the applications of CDs in BTE, including osteogenesis, fluorescence tracing, phototherapy and antibacterial activity, are presented. Finally, the challenges and future perspectives of CDs in BTE are briefly discussed to give a comprehensive picture of CDs. This review provides a theoretical basis and advanced design strategies for the application of CDs in BTE.

Carbon dots nanophotosensitizers with tunable reactive oxygen species generation for mitochondrion-targeted type I/II photodynamic therapy

Carbon dots (CDs) have emerged as promising nanomaterials for bioimaging-guided photodynamic therapy (PDT). However, designing red-emissive CDs (RCDs) with tunable type I and type II reactive oxygen species (ROS) generation to simultaneously meet PDT applications in aerobic and hypoxic scenarios still remain major challenges. Herein, three types of RCDs with maximum emission at approximately 680 nm are successfully prepared. It is noteworthy that they exhibit the adjustable ROS production with equal superoxide anion (via type I PDT) and incremental singlet oxygen (via type II PDT). Detailed structural and optical characterizations along with theoretical calculation reveal that the unique type I/II ROS formation mainly depends on the core sizes and surface states of RCDs, which determine their identical redox potentials and tapering energy gaps between singlet- and triplet states, respectively. Additionally, due to the inherent mitochondria targeting capability, RCDs enable themselves to induce cell programmed death via activating mitochondrion-mediated apoptotic pathways. This work exploits the unprecedented RCDs with tunable type I and type II ROS generation that could ensure highly efficient tumor eradication both in vitro and in vivo, even under the harsh tumor microenvironment, providing a new prospect for CDs as nanophotosensitizers to conquer the limitations of single type PDT.

A Design-assisted Spectrofluorometric Method Utilizing a One-pot Fluorescent Probe for the Quantitation of some Calcium Channel Blockers

Based on their reaction with highly fluorescent carbon quantum dots (CQDts), a precise and reliable spectrofluorometric approach was developed for the determination of three calcium channel blockers. The studied drugs are: lercanidipine, nimodipine and nifedipine. (CQDts) were produced using a one-step hydrothermal method with ascorbic acid as the carbon source. The produced CQDts were capped by alcohol to create yellow emitters displaying a high fluorescence emission at 524 nm when excited at 325 nm. The fluorescence intensity of CQDts was noticeably quenched by each of the three calcium channel blockers. The relation between their concentrations and fluorescence quenching is linear over the concentration range of 0.5-20 µg/mL for each of the three drugs. A full factorial design was used to optimize the effect of variable factors. Therefore, under optimum experimental design conditions, the detection limits for lercanidipine, nimodipine, and nifedipine were 0.11 ± 1.09, 0.10 ± 0.25 and 0.12 ± 0.71 µg/mL, respectively. The LOQ was 0.33, 0.30, and 0.37 µg/mL respectively. The quenching of fluorescent CQDts occurred through the inner filter effect (IFE) for nimodipine, while it was mixed with dynamic quenching for lercanidipine and nifedipine. The proposed method was effectively used to determine the cited drugs in their pharmaceutical products and had an acceptable level of precision. The selectivity of the CQDts system towards the studied drugs was examined indicating no interference from interfering species.

Nanoparticles as Powerful Tools for Crossing the Blood-brain Barrier

The blood-brain barrier (BBB) is considered an important protective barrier in the central nervous system (CNS). The barrier is mainly formed by endothelial cells (ECs) interconnected by various junctions such as tight junctions (TJs), gap junctions, and adherent junctions. They collectively constitute an intensive barrier to the transit of different substances into the brain, selectively permitting small molecules to pass through by passive movement but holding off large ones such as peptides and proteins to cross the brain. Hence some molecules selectively transfer across the BBB by active routes via transcytosis. The BBB also forms a barrier against neurotoxins as well as pathogenic agents. Although various CNS disorders like Alzheimer's disease (AD) and Parkinson's disease (PD) could hamper the integrity of the border. Nevertheless, the BBB acts as a barrier for CNS disorders treatment because it prevents the drugs from reaching their target in the CNS. In recent years, different strategies, including osmotic disruption of BBB or chemical modification of drugs, have been used to transfer the chemotherapeutic agents into brain substances. Nowadays, nanoparticles (NPs) have been used as an effective and non-invasive tool for drug delivery and diagnosis of CNS disorders. In this review, we discuss the structural characteristic of BBB, safe passageways to cross the BBB, and the relation of barrier lesions with different CNS disorders. In the end, we explore the progress in drug delivery, diagnosis, imaging, and treatment of CNS disorders using nanoparticles.

High reactive oxygen species produced from fluorescence carbon dots for anticancer and photodynamic therapies: A review

High-photoluminescence carbon dots (CDs) were synthesized from various sources and various methods using two approaches, namely bottom up and top down, with emission-dependent excitation wavelength. Electronic transition from the higher-occupied molecular orbital (HOMO) state to the lowest-unoccupied molecular orbital(LUMO) state, surface defect states, wider excitation spectrum, higher quantum yield, efficient energy transfer, and element doping affected the fluorescence properties of CDs. Using 102 references listed in this review, the authors studied the relationship between fluorescence mechanism and reactive oxygen species (ROS) produced for photodynamic therapy (PDT) and materials anticancer applications. We described how the radical atom or ROS work as anticancer therapy and PDT and described the chemical reaction of high-resolution fluorescence CDs. We summarized experimental techniques that are used for producing CDs and discussed their characteristics. Finally, conclusions and future prospects in this field are also discussed. The important characteristics of CD-based design for high ROS may usher in new prospects and challenges for high efficiency and stability of PDT and anticancer therapy. In conclusion, we have provided perspectives and challenges of the future development of CD s.

Stimuli-responsive image-guided nanocarriers as smart drug delivery platforms

INTRODUCTION

In recent years, to improve the precision of drug delivery and reduce toxicity associated from the uncontrolled drug release at off-target locations, extensive efforts have been paid to develop stimuli-responsive nanocarriers, which enable precise control over on-demand drug release due to internal stimuli like pH, redox, enzyme and external stimuli like light, magnetic field, and ultrasound. Moreover, some stimuli-responsive nanocarriers have been strategically incorporated with imaging probes for simultaneous monitoring of the drug delivery process and region of interest for treatment optimization.

AREAS COVERED

In this review, the state-of-art progress in developing stimuli-responsive image-guided nanocarriers are summarized, including their designed strategies, synergistic mechanism, and biomedical applications in cancer therapy, and the current challenges and new perspectives are discussed.

EXPERT OPINION

The stimuli-responsive nanocarriers provide assurance for precise release of drugs and imaging probes, and the molecular imaging techniques can monitor the pharmacokinetics, biodistribution and bioavailability of drugs in vivo, and feedback the drug delivery profile. Therefore, stimuli-responsive image-guided nanocarriers can integrate diagnosis and therapy in one nanoplatform and facilitate optimal therapeutic efficacy.

Recent Developments in Heteroatom/Metal-Doped Carbon Dot-Based Image-Guided Photodynamic Therapy for Cancer

Carbon nanodots (CNDs) are advanced nanomaterials with a size of 2-10 nm and are considered zero-dimensional carbonaceous materials. CNDs have received great attention in the area of cancer theranostics. The majority of review articles have shown the improvement of CNDs for use in cancer therapy and bioimaging applications. However, there is a minimal number of consolidated studies on the currently developed doped CNDs that are used in various ways in cancer therapies. Hence, in this review, we discuss the current developments in different types of heteroatom elements/metal ion-doped CNDs along with their preparations, physicochemical and biological properties, multimodal-imaging, and emerging applications in image-guided photodynamic therapies for cancer.

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.

Carbon dots with intrinsic theranostic properties for photodynamic therapy of oral squamous cell carcinoma

Carbon dots (CDs) are one of the carbon-based materials with remarkable optical properties, good water dispersibility and high biocompatibility. However, few studies have emphasized the intrinsic photodynamic and anticancer properties of CDs. Herein, we used CDs as photosensitizers to explore their photodynamic therapy (PDT) effect on oral squamous cell carcinoma (OSCC) cells. The obtained CDs had an effective cellular internalization capacity and possessed good biocompatibility in both CAL-27 and UM1 cells. After irradiation, the CDs showed obvious photodynamic effects on the test cells, which were confirmed by apoptosis analysis. In addition, the CDs exhibited excellent intracellular ROS generation under irradiation, and the subsequent induced cell death may be related to a lysosome-associated pathway.

Molecular imaging nanoprobes for theranostic applications

As a non-invasive imaging monitoring method, molecular imaging can provide the location and expression level of disease signature biomolecules in vivo, leading to early diagnosis of relevant diseases, improved treatment strategies, and accurate assessment of treating efficacy. In recent years, a variety of nanosized imaging probes have been developed and intensively investigated in fundamental/translational research and clinical practice. Meanwhile, as an interdisciplinary discipline, this field combines many subjects of chemistry, medicine, biology, radiology, and material science, etc. The successful molecular imaging not only requires advanced imaging equipment, but also the synthesis of efficient imaging probes. However, limited summary has been reported for recent advances of nanoprobes. In this paper, we summarized the recent progress of three common and main types of nanosized molecular imaging probes, including ultrasound (US) imaging nanoprobes, magnetic resonance imaging (MRI) nanoprobes, and computed tomography (CT) imaging nanoprobes. The applications of molecular imaging nanoprobes were discussed in details. Finally, we provided an outlook on the development of next generation molecular imaging nanoprobes.

High-quality full-color carbon quantum dots synthesized under an unprecedentedly mild condition

Carbon quantum dots (CQDs) are highly promising to be applied in light-emitting, chemosensing, and other cutting-edge domains. Herein, we successfully fabricate high-quality full-color CQDs under unprecedentedly low temperature and pressure (85°C, 1.88 bar). Stable and narrow fluorescent emissions ranging from blue to green and red light were realized by simple amine engineering, which were further mixed into white-light CQDs with the absolute photoluminescent quantum yield reaching 19.2%. The average mass yield of the CQDs reached 69.0%. The optical performances demonstrated that the CQDs possessed uniform luminescent centers and dominant radiative decay channels. Component analysis further suggested that dehydrated condensation between carboxyl and amine groups directed the growth of the CQDs. By utilizing the CQDs, full-color light-emitting diodes and logic gate sensors were developed. This study paves an important step for promoting the application of CQDs by providing an energy-efficient, safe, and productive synthetic strategy.

Optical Microfiber with a Gold Nanorods-Black Phosphorous Nanointerface: An Ultrasensitive Biosensor and Nanotherapy Platform

The detection and therapy of cancers in the early stage significantly alleviate the associated dangers. Optical devices offer new opportunities for these early measures. However, the clinical translation of the existing methods is severely hindered by their relatively low sensitivity or unclear physiological metabolism. Here, an optical microfiber sensor with a drug loading gold nanorod-black phosphorous nanointerface, as an ultrasensitive biosensor and nanotherapy platform, is developed to meet the early-stage requirement. With interface sensitization and functionalization of the hybrid nanointerface, the microfiber sensor presents an ultrahigh sensing performance, achieving the selective detection of the HER2 biomarker with limits of detection of 0.66 aM in buffer solution and 0.77 aM in 10% serum. It can also distinguish breast cancer cells from other cells in the early stage. Additionally, enabled by the interface, the optical microfiber is able to realize cellular nanotherapy, including photothermal/chemotherapy with pump laser coupling after diagnosis, and evaluate therapy results in real time. The immobilization of the interface on the optical microfiber surface prevents the damage to normal cells induced by nanomaterial enrichment, making the device more efficient and intelligent. This study opens up a new avenue for the development of smart optical platforms for sensitive biosensing and precision therapy.

New Generation of Photosensitizers Based on Inorganic Nanomaterials

Advance of nanomaterials and nanotechnology has offered new possibilities for photodynamic therapy (PDT). Large amount of different kinds of sensitizers and targeting moieties can now be loaded in nanometer's volume, which not only results in the improvement of the efficacy of PDT, but also enables the control of image-guided PDT with unprecedented precision and variation. This chapter shall overview the recently most studied inorganic nanomaterials for PDT.

Photoactivatable carbon dots as a label-free fluorescent probe for picric acid detection and light-induced bacterial inactivation

The zero-dimensional carbon nanostructure known as carbon dots showed attractive attributes such as multicolour emission, very high quantum yield, up-conversion, very good aqueous solubility, eco-friendliness, and excellent biocompatibility. These outstanding features of the carbon dots have raised significant interest among the research community worldwide. In the current work, water-soluble nitrogen, silver, and gold co-doped bimetallic carbon dots (BCDs) were prepared using the one-pot hydrothermal method with citric acid as a sole carbon source. As prepared BCDs showed size in the range of 4-8 nm and excitation-independent emission behaviour with maximum emission observed at 427 nm. Additionally, these BCDs showed a very high quantum yield value of 50% and fluorescence lifetime value of 10.1 ns respectively. Interestingly, as prepared BCDs selectively sense picric acid (PA) by exhibiting "selective fluorescence turn-off" behaviour in the presence of PA with a limit of detection value (LOD) of 46 nM. Further, as prepared BCDs were explored for photodynamic therapy to inactivate bacterial growth in the presence of light (400-700 nm) by generating singlet oxygen. Thus as prepared BCDs offer lots of potentials to use a nanoprobe to detect picric acid in an aqueous medium and to design next-generation antibacterial materials.

Yeast powder derived carbon quantum dots for dopamine detection and living cell imaging

Dopamine (DA) is an important neurotransmitter in the brain of mammals. There is a critical need for fast and sensitive determination approaches to monitor these potential diseases due to various weaknesses in clinical trials of the existing methods for DA detection. DA can effectively quench the fluorescence of carbon quantum dots (CDs) through the inner filter effect and static quenching. In this work, fluorescent yeast CDs (Y-CDs) were prepared via a simple hydrothermal approach of using yeast powder and regarded as the fluorescent nanoprobe to directly monitor the DA concentration. The as-prepared detection platform exhibited excellent sensitivity and selectivity toward DA with a low detection limit of 30 nM and a wide linear range of 0.05-150 μM. Benefiting from these outstanding features, the developed label-free method has been successfully applied for fast DA detection in human serum samples with satisfactory recoveries. Furthermore, it demonstrated that the Y-CDs were well suitable for live cell imaging and showed low toxicity toward MCF-7 cells. Consequently, this work will facilitate the great potential of the versatile Y-CDs in developing biosensors for clinical diagnosis and other biological applications.

Screening of Chitosan Derivatives-Carbon Dots Based on Antibacterial Activity and Application in Anti-Staphylococcus aureus Biofilm

Introduction

Pathogenic bacteria, especially the ones with highly organized, systematic aggregating bacteria biofilm, would cause great harm to human health. The development of highly efficient antibacterial and antibiofilm functional fluorescent nanomaterial would be of great significance.

Methods

This paper reports the preparation of a series of antibacterial functional carbon dots (CDs) with chitosan (CS) and its derivatives as raw materials through one-step route, and the impact of various experiment parameters upon the optical properties and the antibacterial abilities have been explored, including the structures of the raw materials, excipients, and solvents.

Results

The CDs prepared by quaternary ammonium salt of chitosan (QCS) and ethylenediamine (EDA) exhibit multiple antibacterial effects through membrane breaking, DNA and protein destroying, and the production of singlet oxygen. The CDs showed excellent broad-spectrum inhibitory activity against a variety of bacteria (Gram-positive and negative bacteria), in particular, to the biofilm of Staphylococcus aureus with minimum inhibitory concentration at 10 µg/mL, showing great potential in killing bacteria and biofilms. The biocompatibility experiments proved that QCS-EDA-CDs are non-toxic to human normal hepatocytes and have low haemolytic effect. Furthermore, the prepared QCS-EDA-CDs have been successfully used in bacterial and biofilm imaging thanks to their excellent optical properties.

Conclusion

This paper explored the preparation and application of functional CDs, which can be used as the visual probe and therapeutic agents in the treatment of infections caused by bacteria and biofilm.

On-demand assembly of polymeric nanoparticles for longer-blood-circulation and disassembly in tumor for boosting sonodynamic therapy

Sonodynamic therapy (SDT) is one of the promising strategies for tumor therapy, but its application is usually hindered by fast clearance in blood-circulation, abnormal tumor microenvironment, and inefficient generation of reactive oxygen species. To solve these problems, we proposed an on-demand assembly-disassembly strategy, where the assembly is favorable for longer-blood-circulation and then the disassembly in tumor is favorable for boosting SDT. Hematoporphyrin monomethyl ether (HMME) as the model of organic sonosensitizers were conjugated with hyaluronic acid (HA). Then HA-HMME was mixed with catalase (CAT) and assembled into polymeric nanoparticles (CAT@HA-HMME NPs) with size of ∼80 nm. CAT@HA-HMME NPs exhibit good biocompatibility and a longer blood half-time (t_1/2 = 4.17 h) which is obviously longer than that (∼0.82 h) of HMME molecules. After HA receptor-mediated endocytosis of cancer cells, CAT@HA-HMME NPs can be cleaved by endogenous hyaluronidase, resulting in the on-demand disassembly in tumor to release HA-HMME molecules and CAT. The CAT catalyzes the endogenous H₂O₂ into O₂ to relieve the hypoxic microenvironment, and the released HA-HMME exhibits a higher ROS generation ability, greatly boosting SDT for the inhibition of tumor growth. Therefore, the on-demand assembly-disassembly strategy may provide some insight in the design and development of nanoagents for tumor therapy.

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On-demand assembly from molecules to nanoparticles for longer-blood-circulation.

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On-demand disassembly in presence of hyaluronidase (in tumor) for boosting sonodynamic effects.

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Efficient damage on cancer cells in-vitro and Significant inhibition of the tumor growth due to the enhanced SDT.

Conjugated polymer nanoparticles and their nanohybrids as smart photoluminescent and photoresponsive material for biosensing, imaging, and theranostics

The emergence of conjugated polymers (CPs) has provided a pathway to attain smart multifunctional conjugated polymer nanoparticles (CPNs) with enhanced properties and diverse applications. CPNs based on π-extended CPs exhibit high fluorescence brightness, low cytotoxicity, excellent photostability, reactive oxygen species (ROS) generation ability, high photothermal conversion efficiency (PCE), etc. which endorse them as an excellent theranostic tool. Furthermore, the unique light-harvesting and energy transfer properties of CPNs enables their transformation into smart functional nanohybrids with augmented performance. Owing to such numerous features, simple preparation method and an easy separation process, the CPNs and their hybrids have been constantly rising as a frontrunner in the domain of medicine and much work has been done in the respective research area. This review summarizes the recent progress that has been made in the field of CPNs for biological and biomedical applications with special emphasis on biosensing, imaging, and theranostics. Following an introduction into the field, a first large section provides overview of the conventional as well as recently established synthetic methods for various types of CPNs. Then, the CPNs-based fluorometric assays for biomolecules based on different detection strategies have been described. Later on, examples of CPNs-based probes for imaging, both in vitro and in vivo using cancer cells and animal models have been explored. The next section highlighted the vital theranostic applications of CPNs and corresponding nanohybrids, mainly via imaging-guided photodynamic therapy (PDT), photothermal therapy (PTT) and drug delivery. The last section summarizes the current challenges and gives an outlook on the potential future trends on CPNs as advanced healthcare material.

Carbon "quantum" dots for bioapplications

Carbon "quantum" dots or carbon dots (CDots) exploit and enhance the intrinsic photoexcited state properties and processes of small carbon nanoparticles via effective nanoparticle surface passivation by chemical functionalization with organic species. The optical properties and photoinduced redox characteristics of CDots are competitive to those of established conventional semiconductor quantum dots and also fullerenes and other carbon nanomaterials. Highlighted here are major advances in the exploration of CDots for their serving as high-performance yet nontoxic fluorescence probes for one- and multi-photon bioimaging in vitro and in vivo, and for their uniquely potent antimicrobial function to inactivate effectively and efficiently some of the toughest bacterial pathogens and viruses under visible/natural or ambient light conditions. Opportunities and challenges in the further development of the CDots platform and related technologies are discussed.

Integration of Au Nanosheets and GdOF:Yb,Er for NIR-I and NIR-II Light-Activated Synergistic Theranostics

The local hyperthermia (>41 °C) effect of photothermal therapy (PTT) is significantly limited by the efficiency of PTT agents to convert laser energy to heat, and such oncotherapy, similar to conventional chemotherapy, invariably encounters the challenge of nonspecific application. Undue reliance on oxygen sources still poses particular difficulties in photodynamic therapy (PDT) for deep-level clinical applications. Considering these therapeutic issues, in this study, we constructed a versatile but unique nanosystem by encapsulating Au nanosheets in codoped gadolinium oxyfluoride (GdOF):Yb,Er spheres, followed by decoration of a chemotherapeutic drug (doxorubicin), photosensitizer (rose Bengal, RB), and targeted agent (folic acid). This allowed the incorporation of cancer treatment and real-time curative efficacy monitoring into one single theranostic nanoplatform. Benefiting from the dual contribution of the strong absorptions in the NIR-I and NIR-II regions, relevant photothermal-conversion efficiency (η) values pertaining to that final product were 39.2% at 1064 nm irradiation and 35.7% at 980 nm illumination. The fluorescence resonance energy transfer that occurred in the up-converted GdOF:Yb,Er to RB contributed to the high PDT efficacy. Combined with a micromeric acid-responsive drug release in a targeted tumor microenvironment, high-performance synergistic therapy was realized. In addition, up-conversion fluorescence imaging and computed tomography imaging accompanied by multimodal magnetic resonance imaging were simultaneously achieved owing to the doped lanthanide ions and the encapsulated Au nanosheets. Our designed oncotherapy nanosystem provides an alternative strategy to acquire ideal theranostic effects.