A photoelectrochemical biosensor for fibroblast-like synoviocyte cell using visible light-activated NCQDs sensitized-ZnO/CH 3 NH 3 PbI 3 heterojunction

Carbon Quantum Dots in Biomedical Applications: Advances, Challenges, and Future Prospects

Carbon quantum dots (CQDs) represent a rapidly emerging class of nanomaterials with significant potential in biomedical applications due to their tunable fluorescence, high biocompatibility, and versatile functionalization. This review focuses on the recent progress in utilizing CQDs for drug delivery, bioimaging, biosensing, and cancer therapy. With their unique optical properties, such as tunable fluorescence, high quantum yield, and photostability, CQDs enable precise bioimaging and sensitive biosensing. Their small size, biocompatibility, and ease of surface functionalization allow for the development of targeted drug delivery systems, enhancing therapeutic precision and minimizing side effects. In cancer therapy, CQDs have shown potential in photodynamic and photothermal treatments by generating reactive oxygen species under light exposure, selectively targeting cancer cells while sparing healthy tissues. Furthermore, CQDs’ ability to penetrate biological barriers including the blood–brain barrier opens new possibilities for delivering therapeutic agents to hard‐to‐reach areas, such as tumors or diseased tissues. However, challenges such as optimizing synthesis, ensuring long‐term stability, and addressing safety concerns in biological environments remain critical hurdles. This review discusses current efforts to overcome these barriers and improve CQD performance in clinical settings, including scalable production methods and enhanced biocompatibility. As research progresses, CQDs are expected to play an important role in improving healthcare by offering more targeted treatment options and contributing to advancements in personalized medicine.

Nanomaterials in the treatment and diagnosis of rheumatoid arthritis: Advanced approaches

Rheumatoid arthritis (RA), a chronic inflammatory condition that affects persons between the ages of 20 and 40, causes synovium inflammation, cartilage loss, and joint discomfort as some of its symptoms. Diagnostic techniques for RA have traditionally been split into two main categories: imaging and serological tests. However, significant issues are associated with both of these methods. Imaging methods are costly and only helpful in people with obvious symptoms, while serological assays are time-consuming and require specialist knowledge. The drawbacks of these traditional techniques have led to the development of novel diagnostic approaches. The unique properties of nanomaterials make them well-suited as biosensors. Their compact dimensions are frequently cited for their outstanding performance, and their positive impact on the signal-to-noise ratio accounts for their capacity to detect biomarkers at low detection limits, with excellent repeatability and a robust dynamic range. In this review, we discuss the use of nanomaterials in RA theranostics. Scientists have recently synthesized, characterized, and modified nanomaterials and biomarkers commonly used to enhance RA diagnosis and therapy capabilities. We hope to provide scientists with the promising potential that nanomaterials hold for future theranostics and offer suggestions on further improving nanomaterials as biosensors, particularly for detecting autoimmune disorders.

Carbon-based photoelectrochemical sensors: recent developments and future prospects

Owing to the considerable potential of photoelectrochemical (PEC) sensors, they have gained significant attention in the analysis of biological, environmental, and food markers. However, the limited charge mass transfer efficiency and rapid recombination of electron hole pairs have become obstacles in the development of PEC sensors. In this case, considering the unique advantages of carbon-based materials, they can be used as photosensitizers, supporting materials and conductive substrates and coupled with semiconductors to prepare composite materials, solving the above problems. In addition, there are many types of carbon materials, which can have semiconductor properties and form heterojunctions after coupling with semiconductors, effectively promoting the separation of electron hole pairs. Herein, we aimed to provide a comprehensive analysis of reports on carbon-based PEC sensors by introducing their research and application status and discussing future development trends in this field. In particular, the types and performance improvement strategies of carbon-based electrodes and the working principles of carbon-based PEC sensors are explained. Furthermore, the applications of carbon-based photoelectric sensors in environmental monitoring, biomedicine, and food detection are highlighted. Finally, the current limitations in the research on carbon-based PEC sensors are emphasized and the need to enhance the sensitivity and selectivity through material modification, structural design, improved device performance, and other strategies are emphasized.

Nanomedicines targeting activated immune cells and effector cells for rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovial inflammation and inflammatory cellular infiltration. Functional cells in the RA microenvironment (RAM) are composed of activated immune cells and effector cells. Activated immune cells, including macrophages, neutrophils, and T cells, can induce RA. Effector cells, including synoviocytes, osteoclasts, and chondrocytes, receiving inflammatory stimuli, exacerbate RA. These functional cells, often associated with the upregulation of surface-specific receptor proteins and significant homing effects, can secrete pro-inflammatory factors and interfere with each other, thereby jointly promoting the progression of RA. Recently, some nanomedicines have alleviated RA by targeting and modulating functional cells with ligand modifications, while other nanoparticles whose surfaces are camouflaged by membranes or extracellular vesicles (EVs) of these functional cells target and attack the lesion site for RA treatment. When ligand-modified nanomaterials target specific functional cells to treat RA, the functional cells are subjected to attack, much like the intended targets. When functional cell membranes or EVs are modified onto nanomaterials to deliver drugs for RA treatment, functional cells become the attackers, similar to arrows. This study summarized how diversified functional cells serve as targets or arrows by engineered nanoparticles to treat RA. Moreover, the key challenges in preparing nanomaterials and their stability, long-term efficacy, safety, and future clinical patient compliance have been discussed here.

Nanotechnology's frontier in combatting infectious and inflammatory diseases: prevention and treatment

Inflammation-associated diseases encompass a range of infectious diseases and non-infectious inflammatory diseases, which continuously pose one of the most serious threats to human health, attributed to factors such as the emergence of new pathogens, increasing drug resistance, changes in living environments and lifestyles, and the aging population. Despite rapid advancements in mechanistic research and drug development for these diseases, current treatments often have limited efficacy and notable side effects, necessitating the development of more effective and targeted anti-inflammatory therapies. In recent years, the rapid development of nanotechnology has provided crucial technological support for the prevention, treatment, and detection of inflammation-associated diseases. Various types of nanoparticles (NPs) play significant roles, serving as vaccine vehicles to enhance immunogenicity and as drug carriers to improve targeting and bioavailability. NPs can also directly combat pathogens and inflammation. In addition, nanotechnology has facilitated the development of biosensors for pathogen detection and imaging techniques for inflammatory diseases. This review categorizes and characterizes different types of NPs, summarizes their applications in the prevention, treatment, and detection of infectious and inflammatory diseases. It also discusses the challenges associated with clinical translation in this field and explores the latest developments and prospects. In conclusion, nanotechnology opens up new possibilities for the comprehensive management of infectious and inflammatory diseases.

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.

Competitive Displacement Triggering DBP Photoelectrochemical Aptasensor via Cetyltrimethylammonium Bromide Bridging Aptamer and Perovskite

Here, a label-free perovskite-based photoelectrochemical (PEC) aptasensor was rationally designed for the displacement assay of dibutyl phthalate (DBP), a well-known endocrine disruptor, with the aid of cetyltrimethylammonium bromide (CTAB). In this method, CTAB significantly enhanced the PEC response and humidity resistance of the CH₃NH₃PbI₃ perovskite by forming a protecting layer and passivating the X- and A-sites vacancies of CH₃NH₃PbI₃. In addition, CTAB facilitated the immobilization of an aptamer through van der Waals and hydrophobicity forces, as well as the electrostatic interactions between the phosphate group of the aptamer and the cationic group of CTAB. When exposed to DBP in the affinity solution, the DBP aptamer was released from the electrode because the affinity between DBP and its aptamer competes with the interaction of the aptamer and CTAB. The displacement of the aptamer from the perovskite surface relieves the block effect and thus enhances the photoelectric signal of perovskite. By virtue of the good photoelectrochemical characters of CH₃NH₃PbI₃ and the specific recognition ability of aptamer, the linear range of the PEC sensor was 1.0 × 10^-13 to 1.0 × 10^-8 M and the detection and quantification limits were down to 2.5 × 10^-14 and 8.2 × 10^-14 M (S/N = 3), respectively. This work offers a novel strategy for designing aptasensors for the detection of various targets and exhibits the marvelous potential of organic-inorganic perovskite in the field of PEC analysis.

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.

A one-step hydrothermal route to fabricate a ZnO nanorod/3D graphene aerogel-sensitized structure with enhanced photoelectrochemistry performance and self-powered photoelectrochemical biosensing of parathion-methyl

A facile one-pot hydrothermal method for fabricating ZnO/GAs was developed. And a novel self-powered PEC biosensor was constructed based on the ZnO/GAs with the amplification of thiocholine for the detection of parathion-methyl.

Carbon source self-heating: ultrafast, energy-efficient and room temperature synthesis of highly fluorescent N, S-codoped carbon dots for quantitative detection of Fe(iii) ions in biological samples

In recent years, photoluminescent (PL) carbon dots (CDs) have attracted enormous attention because of their many fascinating properties. However, the traditional synthesis routes of PL CDs usually suffer from relatively low quantum yields (QYs) and require complicated operation processes as well as lots of externally supplied energy. Herein, we report a room temperature, green, ultrafast and energy-efficient route for large scale synthesis of highly PL N, S-codoped CDs without any external energy supply. The N, S-codoped CDs are prepared through a novel carbon source self-heating strategy, using the sole precursor tetraethylenepentamine (TEPA) simultaneously as the carbon, nitrogen and heat source, triggered by the heat initiator sodium persulfate (Na2S2O8). The large amount of heat released from Na2S2O8-triggered oxidation of TEPA could effectively promote the spontaneous polymerization and carbonization of TEPA precursors themselves as well as the in situ co-doping of sulfur, which had marked synergistic effects on the fluorescence enhancement of CDs, eventually leading to the high-yield (58.0%) preparation of highly fluorescent N, S-codoped CDs (QY 26.4%) at room temperature within 2 min. Moreover, the fluorescence of N, S-codoped CDs could be selectively quenched by Fe3+ ions in the presence of EDTA, in an ultra-wide range of 0.2-600 μM, with a detection limit of 0.10 μM. Ultimately, the fluorescent nanoprobe was successfully used for the quantitative detection of Fe3+ in human serum samples, indicating its great potential for sensing and biomedical applications.

Detection signal amplification strategies at nanomaterial-based photoelectrochemical biosensors

This review focusses on unique material modification and signal amplification strategies reported in developing photoelectrochemical biosensors with utmost sensitivity and selectivity.

A procalcitonin photoelectrochemical immunosensor: NCQDs and Sb2S3 co-sensitized hydrangea-shaped WO3 as a matrix through a layer-by-layer assembly

Electron-transfer mechanism of a PEC immunosensor based on WO₃/NCQDs/Sb₂S₃ composites in PBS electrolytes containing AA.

Recent developments of photoelectrochemical biosensors for food analysis

Recent developments of photoelectrochemical biosensors for food analysis are summarized and the future prospects in this field are discussed.

A sensitive photoelectrochemical assay of miRNA-155 based on a CdSe QDs//NPC-ZnO polyhedra photocurrent-direction switching system and target-triggered strand displacement amplification strategy

A new photoelectrochemical biosensor based on a CdSe QD//NPC-ZnO polyhedra photocurrent-direction switching system and a target-triggered strand displacement amplification strategy was developed for the detection of miRNA-155.

Photoelectrochemical immunoassay of aflatoxin B1 in foodstuff based on amorphous TiO2 and CsPbBr3 perovskite nanocrystals

A split-type photoelectrochemical immunoassay was designed to detect AFB₁ in foodstuffs using amorphous TiO₂ and CsPbBr₃ perovskite nanocrystals.

CsPbBr3 perovskite quantum dots/ZnO inverse opal electrodes: photoelectrochemical sensing for dihydronicotinamide adenine dinucleotide under visible irradiation

All-inorganic perovskite quantum dots (PQDs) have attracted tremendous attention due to their extraordinary optical properties, especially CsPbBr₃ QDs with their high stability and photoluminescence efficiency.

Photoelectrochemical immunosensor for methylated RNA detection based on g-C3N4/CdS quantum dots heterojunction and Phos-tag-biotin

N⁶-methyladenosine (m⁶A) is an enigmatic and abundant internal modification in eukaryotic messenger RNA (mRNA), which could affect various aspects of RNA metabolism and mRNA translation. Herein, a novel photoelectrochemical (PEC) immunosensor was constructed for m⁶A detection based on the inhibition of Cu²⁺ to the photoactivity of g-C₃N₄/CdS quantum dots (g-C₃N₄/CdS) heterojunction, where g-C₃N₄/CdS heterojunction was used as photoactive material, anti-m⁶A antibody as recognition unit for m⁶A-containing RNA, Phos-tag-biotin as link unit and avidin functionalized CuO as PEC signal indicator. When CuO was captured on electrode through biotin-avidin affinity reaction and then treated with HCl, Cu²⁺ could be released and Cu_xS would be formed based on the selective interaction between CdS and Cu²⁺, leading the photocurrent obviously decreased. Under the optimal detection conditions, the PEC biosensor displayed a linear range of 0.01-10nM and a low detection limit of 3.53 pM for methylated RNA determination. Furthermore, the developed method could also be used to detect the expression level of m⁶A methylated RNA in serum samples of breast cancer patient before and after operative treatment. The proposed assay strategy has a great potential for detecting the expression methylation level of RNA in real sample.

Quantum-dots-based photoelectrochemical bioanalysis highlighted with recent examples

Photoelectrochemical (PEC) bioanalysis is a newly developed methodology that provides an exquisite route for innovative biomolecular detection. Quantum dots (QDs) are semiconductor nanocrystals with unique photophysical properties that have attracted tremendous attentions among the analytical community. QDs-based PEC bioanalysis comprises an important research hotspot in the field of PEC bioanalysis due to its combined advantages and potentials. Currently, it has ignited increasing interests as demonstrated by increased research papers. This review aims to cover the most recent advances in this field. With the discussion of recent examples of QDs-PEC bioanalysis from the literatures, special emphasis will be placed on work reporting on fundamental advances in the signaling strategies of QDs-based PEC bioanalysis from 2013 to now. Future prospects in this field are also discussed.

Recent advances in the use of quantum dots for photoelectrochemical bioanalysis

Photoelectrochemical (PEC) bioanalysis is a newly developed technique for innovative biomolecular detection. Quantum dots (QDs) with unique photophysical properties are key components in realization of various exquisite PEC bioanalyses. Particularly, significant progress has been made in the QD-based PEC bioanalysis. In this work, we briefly summarize the most recent and important developments in the use of traditional and newly emerging QDs for novel PEC bioanalytical applications. The future prospects in this dynamic field are also highlighted.

Ultrasensitive photoelectrochemical aptasensing of miR-155 using efficient and stable CH3NH3PbI3 quantum dots sensitized ZnO nanosheets as light harvester

An ultrasensitive photoelectrochemical (PEC) aptasensor based on a novel signal amplification strategy was developed for the quantitative determination of microRNA (miR)-155. CH3NH3PbI3 quantum dots (QDs) functionalized ZnO nanosheets (NSs) were employed as the light harvester. Owing to the synergetic effect between CH3NH3PbI3 QDs and ZnO NSs, ZnO@CH3NH3PbI3 can provide an obviously increasing PEC signal by forming the heterojunction. Due to the larger steric hindrance, the sensitive decrease of the PEC signal can be achieved by the specific recognition between the primers and ssDNA of miR-155. In this sense, this developed aptasensor can achieve a high sensitivity (especially in the presence of the low concentrations of miR-155) and a wide detection range (0.01fmol/L to 20,000pmol/L). Under the optimal conditions, the proposed aptasensor offered an ultrasensitive and specific determination of miR-155 down to 0.005fmol/L. This aptassay method would open up a new promising platform at ultralow levels for early diagnose of different miRNA.

Enhanced photoelectrochemical cytosensing of fibroblast-like synoviocyte cells based on visible light-activated ox-GQDs and carboxylated g-C3N4 sensitized TiO2 nanorods

Scheme A: Schematic illustration of the PEC cytosensor fabrication process, B: schematic illustration of the energy level diagram.