Dual-QDs ratios fluorescent probe for sensitive and stable detection of insulin

Aggregation-Induced Emission Luminogen: Role in Biopsy for Precision Medicine

Biopsy, including tissue and liquid biopsy, offers comprehensive and real-time physiological and pathological information for disease detection, diagnosis, and monitoring. Fluorescent probes are frequently selected to obtain adequate information on pathological processes in a rapid and minimally invasive manner based on their advantages for biopsy. However, conventional fluorescent probes have been found to show aggregation-caused quenching (ACQ) properties, impeding greater progresses in this area. Since the discovery of aggregation-induced emission luminogen (AIEgen) have promoted rapid advancements in molecular bionanomaterials owing to their unique properties, including high quantum yield (QY) and signal-to-noise ratio (SNR), etc. This review seeks to present the latest advances in AIEgen-based biofluorescent probes for biopsy in real or artificial samples, and also the key properties of these AIE probes. This review is divided into: (i) tissue biopsy based on smart AIEgens, (ii) blood sample biopsy based on smart AIEgens, (iii) urine sample biopsy based on smart AIEgens, (iv) saliva sample biopsy based on smart AIEgens, (v) biopsy of other liquid samples based on smart AIEgens, and (vi) perspectives and conclusion. This review could provide additional guidance to motivate interest and bolster more innovative ideas for further exploring the applications of various smart AIEgens in precision medicine.

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.

Nitrogen- and sulfur-doped graphene quantum dots for chemiluminescence

Graphene quantum dots (GQDs), as one of the most promising luminescent nanomaterials, have been receiving increasing attention in various applications. However, it is still a challenge to improve their chemiluminescence (CL) quantum efficiency. Herein, the CL emissions of nitrogen- and sulfur-doped GQDs (NS-GQDs), nitrogen-doped GQDs (N-GQDs) and undoped GQDs synthesized through one-pot high-temperature pyrolysis are investigated in their chemical reactions with bis(2-carbopentyloxy-3,5,6-trichlorophenyl) oxalate (CPPO) and hydrogen peroxide (H₂O₂). A bright blue emission, and yellowish green and yellowish white light from NS-GQDs, N-GQDs and GQDs can be observed, respectively, in the mixture solutions with CPPO and H₂O₂. For the first time, spooling CL spectroscopy was used to investigate the CL reaction mechanisms, illuminant decays and the absolute CL efficiencies of these three GQD systems. Compared with the same system of undoped GQDs, it has been found that the NS-GQDs not only present slower illuminant decay, but also display an absolute CL quantum efficiency of 0.01%, 5-fold enhancement, due to the increase in N and S doping for a well-defined band gap energy. Moreover, three peak wavelengths attributed to intrinsic emission at 425 nm, aggregation-induced emission (AIE) at 575 nm and S-doped emissive surface states at 820 nm are observed for the first time in the NS-GQD system. The CL spectrum of N-GQDs displays two emission peaks at 395 and 575 nm attributed to intrinsic emission and AIE, whereas the CL spectrum of undoped GQDs demonstrates 500 nm and 600 nm peak wavelengths attributed to core emission and AIE. Absolute CL quantum efficiencies from these emissions at these various peaks can be determined quantitatively. This study provides guidance on tuning the surface states of GQD for more conducive injection of electrons and holes, facilitating the production of CL emission, which is beneficial for promoting the development of optical, bioassay and energy conversion applications.

Noncancerous disease-targeting AIEgens

Noncancerous diseases include a wide plethora of medical conditions beyond cancer and are a major cause of mortality around the world. Despite progresses in clinical research, many puzzles about these diseases remain unanswered, and new therapies are continuously being sought. The evolution of bio-nanomedicine has enabled huge advancements in biosensing, diagnosis, bioimaging, and therapeutics. The recent development of aggregation-induced emission luminogens (AIEgens) has provided an impetus to the field of molecular bionanomaterials. Following aggregation, AIEgens show strong emission, overcoming the problems associated with the aggregation-caused quenching (ACQ) effect. They also have other unique properties, including low background interferences, high signal-to-noise ratios, photostability, and excellent biocompatibility, along with activatable aggregation-enhanced theranostic effects, which help them achieve excellent therapeutic effects as an one-for-all multimodal theranostic platform. This review provides a comprehensive overview of the overall progresses in AIEgen-based nanoplatforms for the detection, diagnosis, bioimaging, and bioimaging-guided treatment of noncancerous diseases. In addition, it details future perspectives and the potential clinical applications of these AIEgens in noncancerous diseases are also proposed. This review hopes to motivate further interest in this topic and promote ideation for the further exploration of more advanced AIEgens in a broad range of biomedical and clinical applications in patients with noncancerous diseases.

Label-free Aptasensor for the Ultrasensitive Detection of Insulin Via a Synergistic Fluorescent Turn-on Strategy Based on G-quadruplex and AIEgens

Insulin, the only hormone regulating blood glucose level, is strongly associated with diabetes and its complications. Specific recognition and ultrasensitive detection of insulin are of clinical significance for the early diagnosis and treatment of diabetes. Inspired by aggregation-induced emission, we presented a turn-on label-free fluorescence aptasensor for insulin detection. Quaternized tetraphenylethene salt was synthesized as the fluorescence probe. Guanine-rich aptamer IGA3 was selected as recognition element. Graphene oxide was chosen as the quencher. Under optimized conditions, the fluorescence aptasensor displayed a wide linear range (1.0 pM-1.0 μM) with a low limit of detection (0.42 pM). Furthermore, the aptasensor was successfully applied to detect insulin in human serum. Spiked recoveries were obtained in the range of 96.06%-104.26%. All these results demonstrated that the proposed approach has potential application in the clinical diagnostics of diabetes.

A homogeneous enzyme-free ratiometric immunoassay for the determination of C-peptide

In this study, a homogeneous enzyme-free ratiometric (HOMO- EF-RA) immunoassay was developed for the sensitive detection of C-peptide. In the immunoassay, there have been a miscible detection system by mixing with the fluorescent quantum dots conjugated antigen (QD-Ag conjugates) and the dylight dye conjugated antibody (DL-Ab conjugates). When connecting between Ag-QD conjugate and Ab-DL conjugate by specific recognition, the system emitted fluorescence resonant energy transfer (FRET). The target C-peptide can inhibit the connection and FRET formation between QD-Ag conjugates and DL-Ab conjugates, thus changing the dual fluorescence. By measuring the ratio dual fluorescence changes of the system, the content of C-peptide was evaluated without any enzyme used and multiple incubation and washing steps. This immunoassay realized the highly sensitive (as low as 0.12 ng mL^-1), selective and rapid (as less as 6 min) detection of C-peptide. Furthermore, the the simple and convenient immunoassay was applied successfully to the determination of C-peptide in real serum samples.