Cetuximab-conjugated iodine doped carbon dots as a dual fluorescent/CT probe for targeted imaging of lung cancer cells

Comprehensive Overview of Controlled Fabrication of Multifunctional Fluorescent Carbon Quantum Dots and Exploring Applications

In recent years, carbon dots (CDs) have garnered increasing attention due to their simple preparation methods, versatile performances, and wide-ranging applications. CDs can manifest various optical, physical, and chemical properties including quantum yield (QY), emission wavelength (Em), solid-state fluorescence (SSF), room-temperature phosphorescence (RTP), material-specific responsivity, pH sensitivity, anti-oxidation and oxidation, and biocompatibility. These properties can be effectively regulated through precise control of the CD preparation process, rendering them suitable for diverse applications. However, the lack of consideration given to the precise control of each feature of CDs during the preparation process poses a challenge in obtaining the requisite features for various applications. This paper is to analyze existing research and present novel concepts and ideas for creating CDs with different distinct features and applications. The synthesis methods of CDs are discussed in the first section, followed by a comprehensive overview of the important properties of CDs and the modification strategy. Subsequently, the application of CDs and their requisite properties are reviewed. Finally, the paper outlines the current challenges in controlling CDs properties and their applications, discusses potential solutions, and offers suggestions for future research.

Tumor diagnosis using carbon-based quantum dots: Detection based on the hallmarks of cancer

Carbon-based quantum dots (CQDs) have been shown to have promising application value in tumor diagnosis. Their use, however, is severely hindered by the complicated nature of the nanostructures in the CQDs. Furthermore, it seems impossible to formulate the mechanisms involved using the inadequate theoretical frameworks that are currently available for CQDs. In this review, we re-consider the structure-property relationships of CQDs and summarize the current state of development of CQDs-based tumor diagnosis based on biological theories that are fully developed. The advantages and deficiencies of recent research on CQDs-based tumor diagnosis are thus explained in terms of the manifestation of nine essential changes in cell physiology. This review makes significant progress in addressing related problems encountered with other nanomaterials.

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.

Modulation of Near-Infrared Mitochondria-Targetable fluorescent probe for H2S bioimaging through the modification of heavy atom iodine

H₂S is correlated with mitochondrial dysfunction, which results in the death of cells. Two near-infrared fluorescent probes, Mito-HS-1 and Mito-HS-2, were designed for mitochondrial H₂S imaging. Initially, the synthesis protocol of expensive IR-780-based hemicyanine (HXPI) was optimized with an appreciate yield of 80 % as compared with 14-56 % previously reported. Iodine atom was introduced to HXPI to obtain iodine-HXPI whose Stokes shift was increased to be 90 nm. On account of the rapid and fast nucleophilic attack of H₂S, HXPI-based Mito-HS-1 could be applied for the real time imaging of mitochondrial H₂S. Besides some similar optical properties with Mito-HS-1, iodine-HXPI-based Mito-HS-2 exhibited wider linear range (3-150 μM), more stable fluorescent imaging and more favorable specificity in vitro. Both Mito-HS-1 and Mito-HS-2 could be used to image exogenous H₂S in cells, with Mito-HS-2 showing fairly better signal-to-noise. Additionally, the Pearson correlation coefficient of two probes demonstrated that they could successfully monitor mitochondrial H₂S in A549 cells and Hela cells.

Highly luminescent nitrogen and sulfur co-doped carbon dots for Sn2+ and S2- sensing and dual-mode anti-counterfeiting

The preparation of nitrogen and sulfur co-doped carbon dots (N, S-CDs) with highly bright orange-red fluorescence is reported through a facile solvothermal approach with naphthalenetetracarboxylic dianhydride as starting material. The N, S-CDs exhibited superior properties, including intense long-wavelength emission with a narrow full width at half maxima (FWHM) of 33 nm, high fluorescence quantum yield (QY) of 60.5% in aqueous solution, excitation-independent emission behavior, and excellent water dispersibility. In addition, sulfide ions (S^2-) could selectively recover the fluorescence of N, S-CDs quenched by Sn²⁺. The selective experiment suggested that the N, S-CDs/Sn²⁺ complex could be used as a fluorescence-enhancement sensor for sulfide ions (S^2-), with the linear range of 5-50 μM and the LOD of 0.35 μM. The practicality and feasibility of this sensor for the determination of sulfide ions in tap and lake water were verified with good recoveries. Furthermore, because of their highly bright fluorescence and strong water solubility, the N, S-CDs could be easily fabricated into fluorescent ink and transparent films, demonstrating the promising application in anti-counterfeiting. Therefore, the designed N, S-CDs exhibited the advantages of facile preparation, intense fluorescence, high stability, easy processing, and selective fluorescence change for specific analytes, which showed high potential in fluorescence detection and anti-counterfeiting.

Nanomedical approaches in the realm of rheumatoid arthritis

Rheumatoid arthritis (RA) is a heterogeneous autoimmune inflammatory disorder defined by the damage to the bone and cartilage in the synovium, which causes joint impairment and an increase in the mortality rate. It is associated with an incompletely elucidated pathophysiological mechanism. Even though disease-modifying antirheumatic drugs have contributed to recent improvements in the standard of care for RA, only a small fraction of patients is able to attain and maintain clinical remission without the necessity for ongoing immunosuppressive drugs. The evolution of tolerance over time as well as patients' inability to respond to currently available therapy can alter the overall management of RA. A significant increase in the research of RA nano therapies due to the possible improvements they may provide over traditional systemic treatments has been observed. New approaches to getting beyond the drawbacks of existing treatments are presented by advancements in the research of nanotherapeutic techniques, particularly drug delivery nano systems. Via passive or active targeting of systemic delivery, therapeutic drugs can be precisely transported to and concentrated in the affected sites. As a result, nanoscale drug delivery systems improve the solubility and bioavailability of certain drugs and reduce dose escalation. In the present paper, we provide a thorough overview of the possible biomedical applications of various nanostructures in the diagnostic and therapeutic management of RA, derived from the shortcomings of conventional therapies. Moreover, the paper suggests the need for improvement on the basis of research directions and properly designed clinical studies.

Dye-sensitized lanthanide containing nanoparticles for luminescence based applications

Due to their exceptional luminescent properties, lanthanide (Ln) complexes represent a unique palette of probes in the spectroscopic toolkit. Their extremely weak brightness due to forbidden Ln electronic transitions can be overcome by indirect dye-sensitization from the antenna effect brought by organic ligands. Despite the improvement brought by the antenna effect, (bio)analytical applications with discrete Ln complexes as luminescent markers still suffers from low sensitivity as they are limited by the complex brightness. Thus, there is a need to develop nano-objects that cumulate the spectroscopic properties of multiple Ln ions. This review firstly gives a brief introduction of the spectral properties of lanthanides both in complexes and in nanoparticles (NPs). Then, the research progress of the design of Ln-doped inorganic NPs with capping antennas, Ln-complex encapsulated NPs and Ln-complex surface functionalized NPs is presented along with a summary of the various photosensitizing ligands and of the spectroscopic properties (excited-state lifetime, brightness, quantum yield). The review also emphasizes the problems and limitations encountered over the years and the solutions provided to address them. Finally, a comparison of the advantages and drawbacks of the three types of NP is provided as well as a conclusion about the remaining challenges both in the design of brighter NPs and in the luminescence based applications.

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.

A Review on Carbon Quantum Dots: Synthesis, Photoluminescence Mechanisms and Applications

Carbon quantum dots (CQDs), having outstanding biocompatibility, attractive catalytic performance, excellent optical properties, and valuable environment friendliness, are emerging as a new paradigm to design luminescent devices and show great potential in application fields such as biomedical sensors, optical and photonic devices. And CQDs are known as one of the most promising carbon based nanomaterials in the 21st century. Therefore, it has attracted a lot of attention since it was first discovered in 2004. In this review, we explain the accepted photoluminescence mechanism of CQDs, including fluorescence and phosphorescence. There are two main types of synthesis strategies: top-down approach and bottom-up approach. At the same time, the main application fields, including ion detection, anti-counterfeiting, biological imaging, food safety, sensors, lubrication additives, are reviewed. Finally, the existing bottlenecks, pending problems and prospects for the future of CQDs are discussed.

Halogen-Doped Carbon Dots: Synthesis, Application, and Prospects

Carbon dots (CDs) have many advantages, such as tunable photoluminescence, large two-photon absorption cross-sections, easy functionalization, low toxicity, chemical inertness, good dispersion, and biocompatibility. Halogen doping further improves the optical and physicochemical properties of CDs, extending their applications in fluorescence sensors, biomedicine, photocatalysis, anti-counterfeiting encryption, and light-emitting diodes. This review briefly describes the preparation of CDs via the “top-down” and “bottom-up” approaches and discusses the preparation methods and applications of halogen (fluorine, chlorine, bromine, and iodine)-doped CDs. The main challenges of CDs in the future are the elucidation of the luminescence mechanism, fine doping with elements (proportion, position, etc.), and their incorporation in practical devices.

Intrinsic Dual-Emitting Carbon Quantum-Dot-Based Selective Ratiometric Fluorescent Mercaptopurine Detection

Mercaptopurine (6-MP), an immunosuppressive drug, has been widely prescribed for treating leukemia and autoimmune diseases. The level of the 6-MP drug in body fluids is of great interest due to the severe health problems related to its overdose. This study used a facile microwave preparation route to synthesize carbon quantum dots (CQDs) using glutathione and formamide as carbon sources. The obtained monodispersed quantum dots showed dual fluorescence emission with a sensitive affinity toward the 6-MP drug. The sensor's response was optimized by tuning the temperature, pH, and volume ratio of the probe. The prepared ratiometric fluorescence method showed accurate measurements for determining mercaptopurine in aqueous solutions in the concentration range of 1.4-7.6 mg L^-1 with the limit of detection of 1.3 mg L^-1. The sensor's performance was assessed in complex solutions, human urine, and human plasma sample and recovery values in the range of 88-127% were obtained. The reliable dual fluorometric sensor showed promising results for 6-MP determination and potential application for the determination of other chemical and biochemical species.

Precursor structure-determined fluorescence labeling for mesenchymal stem cells among four polyethylenimine-based carbon quantum dots

A series of polyethylenimine (PEI)-based CQDs have been synthesized via a hydrothermal method by mixing linear PEI with linear citric acid (CA with COOH groups, PEICA), linear glucose (G with OH groups, PEIG), cyclic hyaluronic acid (HA with COOH groups, PEIHA) and cyclic boron nitride (BN with OH groups, PEIBN). PEICA had the best labeling effect (100.00 ± 0.26%) and the lowest cytotoxicity (100.89 ± 18.00%) for mesenchymal stem cells (MSCs), followed by PEIG (91.83 ± 7.60%; 92.84 ± 5.56%), PEIHA (84.34 ± 7.87%; 61.27 ± 11.34%) and PEIBN (1.33 ± 0.84%; 22.72 ± 11.47%). The labeling effect of PEIHA for MSCs is lower than that of PEIG because the surface potential of PEIHA (6.58 mV) is higher than that of PEIG (0.50 mV). For PEIBN, it is likely that the precursor (BN) is less biocompatible than CA, HA and glucose. Thus, the linear acid (CA) is more appropriate to react with PEI for synthesizing CQDs with high labeling performance for MSCs. The control experimental results show that factors (such as surface potential, aromatic component, etc.) may all contribute to MSC labeling by PEICA. This work is helpful to design CQDs with high MSC labeling efficiency.

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

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

PEG-4000 formed polymeric nanoparticles loaded with cetuximab downregulate p21 &stathmin-1 gene expression in cancer cell lines

Cetuximab (CTX) is known to have cytotoxic effects on several human cancer cells in vitro; however, as CTX is poorly water soluble, there is a need for improved formulations can reach cancer cells at high concentrations with low side effects. We developed (PEG-4000) polymeric nanoparticles (PEGNPs) loaded with CTX and evaluated their in vitro cytotoxicity and anticancer properties against human lung (A549) and breast (MCF-7) cancer cells. CTX-PEGNPs were formulated using the solvent evaporation technique, and their morphological properties were evaluated. Further, the effects of CTX-PEGNPs on cell viability using the MTT assay and perform gene expression analysis, DNA fragmentation measurements, and the comet assay. CTX-PEGNP showed uniformly dispersed NPs of nano-size range (253.7 ± 0.3 nm), and low polydispersity index (0.16) indicating the stability and uniformity of NPs. Further, the zeta potential of the preparations was -17.0 ± 1.8 mv. DSC and FTIR confirmed the entrapping of CTX in NPs. The results showed IC₅₀ values of 2.26 μg/mL and 1.83 μg/mL for free CTX and CTX-PEGNPs on the A549 cancer cell line, respectively. Moreover, CTX-PEGNPs had a lower IC₅₀ of 1.12 μg/mL in MCF-7 cells than that of free CTX (2.28 μg/mL). The expression levels of p21 and stathmin-1 were significantly decreased in both cell lines treated with CTX-PEGNPs compared to CTX alone. The CTX-PEGNP-treated cells also showed increased DNA fragmentation rates in both cancer cell lines compared with CTX alone. The results indicated that CTX-PEGNP was an improved formulation than CTX alone to induce apoptosis and DNA damage and inhibit cell proliferation through the downregulation of P21 and stathmin-1 expression.

Self-doping synthesis of iodine–carbon quantum dots for sensitive detection of Fe(iii) and cellular imaging

Iodine-doped carbon quantum dots (I-CQDs) were synthesized via p-iodobenzoic acid self-doping for the detection of ferric ions (Fe3+) and cell imaging.

Oxidation triggered formation of polydopamine-modified carboxymethyl cellulose hydrogel for anti-recurrence of tumor

In this research, a hydrogel that combined the tumor photodynamic therapy (PDT) and photothermal therapy (PTT) ability was designed, using dopamine-modified sodium carboxymethyl cellulose (CMC-DA) as the matrix and Chlorin e6 (Ce6) as the photosensitizer. The gel formation was initiated by adding the oxidizing agent sodium periodate (NaIO₄) to the CMC-DA solution, during which the dopamine was simultaneously oxidized to polydopamine (PDA) and NaIO₄ was reduced to sodium iodide (NaI). The formed NaI was encapsulated in the hydrogel and endowed the hydrogel with computerized tomography (CT) imaging ability to monitor the hydrogel degradation and the tumor therapy process. Moreover, the photosensitizer Ce6 can be loaded by the gel system via directly soaking the hydrogel in the Ce6 solution. Under the near-infrared light irradiation, Ce6 can produce cytotoxic reactive oxygen species and the PDA can produce heat to trigger the tumor PDT and PTT respectively to eradicate the tumor recurrence. In general, the designed hydrogel is biocompatible and biodegradable, has a good photothermal conversion, drug loading and CT imaging ability, which laid the foundation for the rational design of biodegradable hydrogels for multifunctional applications.

State of the Art and Perspectives on the Biofunctionalization of Fluorescent Metal Nanoclusters and Carbon Quantum Dots for Targeted Imaging and Drug Delivery

The interface of nanobio science and cancer nanomedicine is one of the most important current frontiers in research, being full of opportunities and challenges. Ultrasmall fluorescent metal nanoclusters (MNCs) and carbon quantum dots (CQDs) have emerged as promising fluorescent nanomaterials due to their unique physicochemical and optical properties, facile surface functionalization, good photostability, biocompatibility, and aqueous dispersity. These characteristics make them advantageous over conventional fluorophores such as organic dye molecules and semiconductor quantum dots (QDs) for the detection, diagnosis, and treatment of various diseases including cancer. Recently, researchers have focused on the biofunctionalization strategy of the MNCs and CQDs which can tailor their physicochemical and biological properties and, in turn, can empower these biofunctionalized nanoprobes for diverse applications including imaging, drug delivery, theranostics, and other biomedical applications. In this invited feature article, we first discuss some fundamental structural and physicochemical characteristics of the fluorescent biocompatible quantum-sized nanomaterials which have some outstanding features for the development of multiplexed imaging probes, delivery vehicles, and cancer nanomedicine. We then demonstrate the diverse surface engineering of these fluorescent nanomaterials with reactive target specific functional groups which can help to construct multifunctional nanoprobes with improved targeting capabilities having minimal toxicity. The promising future of the biofunctionalized fluorescent quantum-sized nanomaterials in the field of bioanalytical and biomedical research is elaborately demonstrated, showing selected recent works with relevant applications. This invited feature article finally ends with a short discussion of the current challenges and future prospects of the development of these bioconjugated/biofunctionalized nanomaterials to provide insight into this burgeoning field of MNC- and CQD-based diagnostics and therapeutic applications.

The Application of Inorganic Nanoparticles in Molecular Targeted Cancer Therapy: EGFR Targeting

Epidermal growth factor receptor (EGFR) is an anticancer drug target for a number of cancers, such as non-small cell lung cancer. However, unsatisfying treatment effects, terrible side-effects, and development of drug resistance are current insurmountable challenges of EGFR targeting treatments for cancers. With the advancement of nanotechnology, an increasing number of inorganic nanomaterials are applied in EGFR-mediated therapy to improve those limitations and further potentiate the efficacy of molecular targeted cancer therapy. Given their facile preparation, easy modification, and biosecurity, inorganic nanoparticles (iNPs) have been extensively explored in cancer treatments to date. This review presents an overview of the application of some typical metal nanoparticles and nonmetallic nanoparticles in EGFR-targeted therapy, then discusses and summarizes the relevant advantages. Moreover, we also highlight future perspectives regarding their remaining issues. We hope these discussions inspire future research on EGFR-targeted iNPs.

Gadolinium-doped carbon dots with high-performance in dual-modal molecular imaging

Carbon dots (CDs), possessing unexpected advantages of photostability, biocompatibility and low toxicity, are regarded as novel nanomaterials in fluorescence (FL) imaging. Doping Gd element in CDs makes them have the ability to be used for magnetic resonance (MR) and FL imaging simultaneously. However, CDs reported before exhibit obvious defects like low photoluminescence (PL) quantum yield (QY) or biotoxicity. In this work, we use gadolinium meglumine, a material with relatively low biotoxicity, along with citric acid and diethylenetriamine to synthesize Gd-doped CDs (Gd-CDs) by a one-step hydrothermal method. The prepared Gd-CDs exhibit excitation-independent emission with a PL QY of 78.05% and a longitudinal relaxivity of 7.37 mM^-1 S^-1, which endows the composite with high-performance in MR/FL imaging. Meanwhile, the FL intensity of Gd-CDs remains stable in the presence of multiple amino acids, which indicates that the FL imaging effect should not be impacted significantly in microenvironments in vivo. In addition to the inconspicuous cytotoxicity, Gd-CDs could be used efficiently for dual-modal molecular imaging to detect diseases such as tumors in the early stages.

Biocompatible sulfur nitrogen co-doped carbon quantum dots for highly sensitive and selective detection of dopamine

In this work, sulfur and nitrogen co-doped carbon quantum dots (S,N-CQDs) were prepared via one-pot hydrothermal treatment of EDTA disodium and sodium sulfide. The prepared S,N-CQDs were characterized by TEM, XRD, FT-IR, XPS, UV-vis absorption and fluorescence spectra to characterize their morphology, crystal structure, functional groups, elemental composition, and optical properties. It was found that S and N elements were successfully doped into the CQDs and the morphology was approximately spherical with an average particle size of 2.16 nm, in which the excitation/emission wavelengths were 350 and 420 nm, respectively. Compared with single element doped CQDs, double element doped CQDs have a higher quantum yield and excellent optical stability. Cell experiments showed that S,N-CQDs had good biocompatibility because they had no obvious toxicity on both normal cell lines and cancer cell lines. More importantly, based on the synergy of static quenching and dynamic quenching, the S,N-CQDs were used as effective fluorescent probes for sensitive detection of DA, with high anti-interference and low limit of detection. Based on the good biocompatibility of S,N-CQDs, the detection of dopamine in actual serum samples were carried out and the results showed an excellent recovery rate. Therefore, this work provides a dopamine sensor with a practical application prospect.

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.

Carbon dots for specific "off-on" sensing of Co2+ and EDTA for in vivo bioimaging

Fluorescent carbon dots (CDs) were hydrothermally synthesized from a mixture of frozen tofu, ethylenediamine and phosphoric acid in an efficient 64% yield. The resulting CDs exhibit good water solubility, low cytotoxicity, high stability, and excellent biocompatibility. The CDs selectively and sensitively detect Co²⁺ through fluorescent quenching with a detection limit of 58 nM. Fluorescence can be restored through the introduction of EDTA, and this phenomenon can be used to quantify EDTA in solution with a detection limit of 98 nM. As both analytes are detected by the same CD platform, this is an "off-on" fluorescence sensor for Co²⁺ and EDTA. The technique's robustness for real-world samples was illustrated by quantifying cobalt in tap water and EDTA in contact lens solution. The CDs were also evaluated for in vivo imaging as they show low cytotoxicity and excellent cellular uptake. In a zebrafish model, the CDs are rapidly adsorbed from the intestine into the liver, and are essentially cleared from the body in 24 h with no appreciable bioaccumulation. Their simple and efficient synthesis, combined with excellent physical and chemical performance, renders these CDs attractive candidates for theranostic applications in targeted "smart" drug delivery and bioimaging.

Advances in inorganic-based colloidal nanovehicles functionalized for nitric oxide delivery

Nitric oxide (NO) is an important pharmaceutical agent of considerable therapeutic interest ascribed to its vasodilative, tumoricidal and antibacterial effects. Rapid development of functional nanomaterials has provided opportunities for us to achieve controllable exogenous delivery of NO. In the current review, a variety of functionalized colloidal nanovehicles that have been developed to date for nitric oxide delivery are reported. Specifically, we focus on inorganic nanomaterials such as semiconductor quantum dots, silica nanoparticles, upconversion nanomaterials, carbon/graphene nanodots, gold nanoparticles, iron oxide nanoparticles as the functional or/and supporting materials to carry NO donors. N-diazeniumdiolates, S-nitrosothiols, nitrosyl metal complexes and organic nitrates as main types of NO donors have their own unique properties and molecular structures. Conjugating the NO donors of different forms with appropriate nanomaterials results in NO delivery nanovehicles capable of releasing NO in a dose-controllable or/and on-demand manner. We also consider the therapeutic applications of those NO delivery nanovehicles, especially their applications for cancer therapy. In the end, we discuss possible future directions for developing exogenous NO delivery systems with more desired structure and improved performance. This review aims to offer the readers an overall view of the advances in functionalized colloidal nanovehicles for NO delivery. It will be attractive to scientists and researchers in the areas of material science, nanotechnology, biomedical engineering, chemical biology, etc.

Recent advances in nanoscale materials for antibody-based cancer theranostics

The quest for advanced management tools or options of various cancers has been on the rise to efficiently reduce their risks of mortality without the demerits of conventional treatments (e.g., undesirable side effects of the medications on non-target tissues, non-targeted distribution, slow clearance of the administered drugs, and the development of drug resistance over the duration of therapy). In this context, nanomaterials-antibody conjugates can offer numerous advantages in the development of cancer theranostics over conventional delivery systems (e.g., highly specific and enhanced biodistribution of the drug in targeted tissues, prolonged systemic circulation, low toxicity, and minimally invasive molecular imaging). This review comprehensively discusses and evaluates recent advances in the application of nanomaterial-antibody bioconjugates for cancer theranostics for the further advancement in the control of diverse cancerous diseases. Further, discussion is expanded to cover the various challenges and limitations associated with the design and development of nanomaterial-antibody conjugates applicable towards better management of cancer.

Current trends in pyrrole and porphyrin-derived nanoscale materials for biomedical applications

This article is written to provide an up-to-date review of pyrrole-based biomedical materials. Porphyrins and other tetrapyrrolic molecules possess unique magnetic, optical and other photophysical properties that make them useful for bioimaging and therapy. This review touches briefly on some of the synthetic strategies to obtain porphyrin- and tetrapyrrole-based nanoparticles, as well as the variety of applications in which crosslinked, self-assembled, porphyrin-coated and other nanoparticles are utilized. We explore examples of these nanoparticles' applications in photothermal therapy, drug delivery, photodynamic therapy, stimuli response, fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, computed tomography and positron emission tomography. We anticipate that this review will provide a comprehensive summary of pyrrole-derived nanoparticles and provide a guideline for their further development.

Facile Preparation of Phthalocyanine-Based Nanodots for Photoacoustic Imaging and Photothermal Cancer Therapy In Vivo

The development of near-infrared (NIR)-absorbing nanoagents for personalized multifunctional phototheranostics has attracted considerable attention in the past decade. Recently, the organic nanomaterials with good biosafety are considered as promising phototheranostic agents, while their facile synthesis remains challenging. Inspired by the preparation of carbon nanodots, we fabricate the NIR-absorbing phthalocyanine-based nanodots (ZnPc-NDs) using a facile method for multifunctional phototheranostics. The significant aggregation of phthalocyanines in nanodots induces a complete fluorescence quenching, which affords a high photothermal conversion efficiency (η = 45.7%). The ZnPc-NDs disperse very well in water media with an average diameter around 80 nm. Further conjugation of biotin on the surface of ZnPc-NDs affords tumor-targeting phthalocyanine nanodots (ZnPc-BT). The ZnPc-BT are demonstrated with favorable biocompatibility, intense photoacoustic signals, high tumor accumulation, and effective tumor suppression in vivo. This Article provides a new insight for further developing nanomedicines with imaging and therapeutic functions to treat cancers precisely and effectively.

Photonic Carbon Dots as an Emerging Nanoagent for Biomedical and Healthcare Applications

As a class of carbon-based nanomaterials, carbon dots (CDs) have attracted enormous attention because of their tunable optical and physicochemical properties, such as absorptivity and photoluminescence from ultraviolet to near-infrared, high photostability, biocompatibility, and aqueous dispersity. These characteristics make CDs a promising alternative photonic nanoagent to conventional fluorophores in disease diagnosis, treatment, and healthcare managements. This review describes the fundamental photophysical properties of CDs and highlights their recent applications to bioimaging, photomedicine (e.g., photodynamic/photothermal therapies), biosensors, and healthcare devices. We discuss current challenges and future prospects of photonic CDs to give an insight into developing vibrant fields of CD-based biomedicine and healthcare.

A Simple Strategy to Fabricate Phthalocyanine-Encapsulated Nanodots for Magnetic Resonance Imaging and Antitumor Phototherapy

Photothermal agents can transfer the absorbed light to heat energy, offering a noninvasive and controllable method to kill tumor cells and tissues. Here, we develop a simple and high-output strategy to prepare photothermal nanodots (MnPc-NDs) by the self-assembly and carbonization of manganese phthalocyanine. The aggregation of phthalocyanine molecules in the nanodots induces an efficient photothermal conversion. Thanks to the high thermal stability of phthalocyanine, the macrocycle is well preserved in the core of nanodots under the controlled hydrothermal temperature. Moreover, the as-prepared MnPc-NDs disperse well in aqueous solution with an average nanoscale size around 60 nm. The intense absorption in near-infrared (NIR) region, along with efficient reactive oxygen generation, high photothermal conversion efficiency (η = 59.8%), and excellent magnetic resonance contrast performances of MnPc-NDs endow them with great potential for MRI-guided cancer phototherapy. Therefore, the contribution provides a facile way to develop theranostic MnPc-NDs for precise and efficient cancer imaging and therapy.

A review: recent advances in preparations and applications of heteroatom-doped carbon quantum dots

Carbon quantum dots (CQDs) are widely used in optoelectronic catalysis, biological imaging, and ion probes owing to their low toxicity, stable photoluminescence, and ease of chemical modification. However, the low fluorescence yield and monochromatic fluorescence of CQDs limit their practical applications. This review summarizes the commonly used approaches for improving the fluorescence efficiency of CQDs doped with non-metallic (heteroatom) elements. Herein, three types of heteroatom-doped CQDs have been investigated: (1) CQDs doped with a single heteroatom; (2) CQDs doped with two heteroatoms; and (3) CQDs doped with three heteroatoms. The limitations and future perspectives of doped CQDs from the viewpoint of producing CQDs for specific applications, especially for bioimaging and light emitting diodes, have also been discussed herein.

Multifunctional nanomedicines for targeting epidermal growth factor receptor in colorectal cancer

Systemic administration of chemotherapeutics by nanocarriers (NCs) functionalized with targeting agents provides a localized accumulation of drugs in the target tissues and cells. Advanced nanoscaled medicaments can enter into the tumor microenvironment (TME) and overcome the uniquely dysregulated biological settings of TME, including highly pressurized tumor interstitial fluid in an acidic milieu. Such multimodal nanomedicines seem to be one of the most effective treatment modalities against solid tumors such as colorectal cancer (CRC). To progress and invade, cancer cells overexpress various oncogenes and molecular markers such as epidermal growth factor receptors (EGFRs), which can be exploited for targeted delivery of nanoscaled drug delivery systems (DDSs). In fact, to develop effective personalized multimodal nanomedicines, the type of solid tumor and status of the disease in each patient should be taken into consideration. While the development of such multimodal-targeted nanomedicines is largely dependent on the expression level of oncomarkers, the type of NCs and homing/imaging agents play key roles in terms of their efficient applications. In this review, we provide deep insights into the development of EGFR-targeting nanomedicines and discuss various types of nanoscale DDSs (e.g., organic and inorganic nanoparticles) for targeting of the EGFR-positive solid tumors such as CRC.

Bottom-up synthesis of nitrogen and oxygen co-decorated carbon quantum dots with enhanced DNA plasmid expression

In this paper, a bottom-up hydrothermal route is reported for the synthesis of oxygen and nitrogen co-decorated carbon quantum dots (CQDs) using ammonium hydrogen citrate (AHC) as a single precursor. DLS data approved the formation of 4.0 nm (average size) CQDs. XRD pattern shows the interlayer spacing (002) of 3.5 Å for CQDs, which is exactly the same as that of crystalline graphite. XPS and FTIR spectra verified the formation of oxygen and nitrogen functional groups on the CQDs surface. Co-decorated carboxyl, hydroxyl and amine groups on the CQDs surfaces make them as promising polyelectrolyte for gene delivery. Toxicity assay showed a survival rate of 70% under different incubation times and up to 500 μg/mL. The highly water-soluble, stable fluorescence and low toxic CQDs increased the gene expression of DNA plasmid in E. coli bacteria 4-fold more than the control group.

Sulforaphane-Conjugated Carbon Dots: A Versatile Nanosystem for Targeted Imaging and Inhibition of EGFR-Overexpressing Cancer Cells

Because of the demand for precision medicine, the investigatation on the application of carbon-dots-based nanosystems in the field of biomedicine is attracting more and more attention. Therefore, we have built a multifunctional nanosystem based on sulforaphane-conjugated carbon dots (SFN-CDs) with thiourea skeleton and applied for EGFR-overexpressing cancer cells targeted imaging and inhibiting. The SFN-CDs are formed by grafting sulforaphane on the amino-rich yellow fluorescent carbon dots, which have excellent optical stability and can be distinguished from normal cells for targeted imaging of cancer cells. The vitro toxicity experiments demonstrated that the SFN-CDs can effectively inhibit EGFR-overexpressing cancer cell proliferation at concentrations below 100 μg mL^-1. All these results validated that SFN-CDs nanoparticles with integration of diagnostic and therapeutic functions can be used as a potential nanodurg in early stage of cancer control. Moreover, this work provides useful insight into targeted nanoparticle design in the biological nanomedicine field.

Carbon Nitride Dots: A Selective Bioimaging Nanomaterial

In contrast to the recent immense attention in carbon nitride quantum dots (CNQDs) as a heteroatom-doped carbon quantum dot (CQD), their biomedical applications have not been thoroughly investigated. Targeted cancer therapy is a prominently researched area in the biomedical field. Here, the ability of CNQDs as a selective bioimaging nanomaterial was investigated to assist targeted cancer therapy. CNQDs were first synthesized using four different precursor sets involving urea derivatives, and the characteristics were compared to select the best candidate material for bioapplications. Characterization techniques such as UV-vis, luminescence, X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy, and transmission electron microscopy were used. These CNQDs were analyzed in in vitro studies of bioimaging and labeling using pediatric glioma cells (SJGBM2) for possible selective biolabeling and nanodistribution inside the cell membrane. The in vitro cellular studies were conducted under long-wavelength emission without the interference of blue autofluorescence. Thus, excitation-dependent emission of CNQDs was proved to be advantageous. Importantly, CNQDs selectively entered SJGBM2 tumor cells, while it did not disperse into normal human embryonic kidney cells (HEK293). The distribution studies in the cell cytoplasm indicated that CNQDs dispersed into lysosomes within approximately 6 h after the incubation. The CNQDs exhibited great potential as a possible nanomaterial in selective bioimaging and drug delivery for targeted cancer therapy.

Ln(III) chelates-functionalized carbon quantum dots: Synthesis, optical studies and multimodal bioimaging applications

The carbon quantum dots termined with amine groups (CQDs-NH₂) were synthesized in one-pot hydrothermal method with citric acid as carbon source and branched polyethylenimine (BPEI) as passive agent, which was then covalently linked to 1, 4, 7, 10-tetraazacyclononane (DOTA) framework to yield CQDs-DOTA. The CQDs-DOTA provide excellent ligand scaffolds for the chelation of lanthanide ions, yielding the related complexes CQDs-DOTA-Ln (Ln = Eu, Tb, Yb and Gd). The successful preparation of CQDs-DOTA-Ln was validated by TEM, XRD, XPS, and FT-IR spectroscopy. The CQDs-DOTA-Ln (Ln = Eu, Tb and Yb) exhibited the characteristic emissions of related lanthanide ions, indicating the CQDs could sensitize the luminescence of lanthanide ions. Besides, the CQDs-DOTA-Gd could serve as an excellent T1-weighted MR imaging probe due to the chelation of paramagnetic Gd (III) ions and good hydrophilicity. The cytotoxicity of CQDs-DOTA-Ln was evaluated through MTT assay upon HeLa cells. The images from fluorescence microscopy further verified their applications in bioimaging in vitro. Due to the good biocompatibility, low toxicity, and high contrast efficiency, the CQDs-DOTA-Ln with Vis/NIR fluorescence and MR multi-modal imaging performance could be used as potential contrast agents for clinic applications.

Carbon Dots @ Platinum Porphyrin Composite as Theranostic Nanoagent for Efficient Photodynamic Cancer Therapy

Photosensitizers are light-sensitive molecules that are highly hydrophobic, which poses a challenge to their use for photodynamic therapy. Hence, considerable efforts have been made to develop carriers for the delivery of PSs. Herein, we synthesized a new theranostic nanoagent (CQDs@PtPor) through the electrostatic interaction between the tetraplatinated porphyrin complex (PtPor) and the negatively charged CQDs. The size and morphology of as-prepared CQDs and CQDs@PtPor were characterized by a series of methods, such as XRD, TEM, XPS, and FTIR spectroscopy. The CQDs@PtPor composite integrates the optical properties of CQDs and the anticancer function of porphyrin into a single unit. The spectral results suggested the effective resonance energy transfer from CQDs to PtPor in the CQDs@PtPor composite. Impressively, the CQDs@PtPor composite showed the stronger PDT effect than that of organic molecular PtPor, suggesting that CQDs@PtPor is advantageous over the conventional formulation, attributable to the enhanced efficiency of 1O2 production of PtPor by CQDs. Thus, this CQDs-based drug nanocarrier exhibited enhanced tumor-inhibition efficacy as well as low side effects in vitro, showing significant application potential in the cancer therapy.