Modular Design of Peptide- or DNA-Modified AIEgen Probes for Biosensing Applications

A Self-Powered Biochemical Sensor for Intelligent Agriculture Enabled by Signal Enhanced Triboelectric Nanogenerator

Precise agriculture based on intelligent agriculture plays a significant role in sustainable development. The agricultural Internet of Things (IoTs) is a crucial foundation for intelligent agriculture. However, the development of agricultural IoTs has led to exponential growth in various sensors, posing a major challenge in achieving long-term stable power supply for these distributed sensors. Introducing a self-powered active biochemical sensor can help, but current sensors have poor sensitivity and specificity making this application challenging. To overcome this limitation, a triboelectric nanogenerator (TENG)-based self-powered active urea sensor which demonstrates high sensitivity and specificity is developed. This device achieves signal enhancement by introducing a volume effect to enhance the utilization of charges through a novel dual-electrode structure, and improves the specificity of urea detection by utilizing an enzyme-catalyzed reaction. The device is successfully used to monitor the variation of urea concentration during crop growth with concentrations as low as 4 µm, without being significantly affected by common fertilizers such as potassium chloride or ammonium dihydrogen phosphate. This is the first self-powered active biochemical sensor capable of highly specific and highly sensitive fertilizer detection, pointing toward a new direction for developing self-powered active biochemical sensor systems within sustainable development-oriented agricultural IoTs.

A Universal and Programmable Platform based on Fluorescent Peptide-Conjugated Probes for Detection of Proteins in Organelles of Living Cells

Realizing protein analysis in organelles of living cells is of great significance for developing diagnostic and therapeutic methods of diseases. Fluorescent-labeled antibodies with well imaging performance and high affinity are classical biochemical tools for protein analysis, while due to the inability to effectively enter into cells, not to mention organelles and the uncontrollable reaction sites that might cause antibodies inactivation when chemically modification, they are hard to apply to living cells. Inspired by the structure of fluorescent-labeled antibodies, we designed as a universal detection platform that was based on the peptide-conjugated probes (PCPs) and consisted of three parts: a) a rotor type fluorescent molecular scaffold for conjugation and signal output; b) the cell penetration protein recognition unit; c) the subcellular organelle targeting unit. In living cells, PCPs could firstly localize at organelles and then proceed protein specific recognition, thus jointly leading to the restriction of twisted intramolecular charge transfer and activation of fluorescence signal. As a proof-of-concept, six different proteins in three typical intracellular organelles could be detected by our platform through simply replacing the recognition sequence of proteins and matching organelle targeting units. The position and intensity of fluorescence signals demonstrated specificity of PCPs and universality of the platform.

Tuning Molecular Motion Enhances Intrinsic Fluorescence in Peptide Amphiphile Nanofibers

Peptide amphiphiles (PAs) are highly tunable molecules that were recently found to exhibit aggregation-induced emission (AIE) when they self-assemble into nanofibers. Here, we leverage decades of molecular design and self-assembly study of PAs to strategically tune their molecular motion within nanofibers to enhance AIE, making them a highly useful platform for applications such as sensing, bioimaging, or materials property characterization. Since AIE increases when aggregated molecules are rigidly and closely packed, we altered the four most closely packed amino acids nearest to the hydrophobic core by varying the order and composition of glycine, alanine, and valine pairs. Of the six PA designs studied, C16VVAAK2 had the highest quantum yield at 0.17, which is a more than 10-fold increase from other PA designs including the very similar C16AAVVK2, highlighting the importance of precise amino acid placement to anchor rigidity closest to the core. We also altered temperature to increase AIE. C16VVAAK2 exhibited an additional 4-fold increase in maximum fluorescence intensity when the temperature was raised from 5 to 65 °C. As the temperature increased, the secondary structure transitioned from β-sheet to random coil, indicating that further packing an already aligned molecular system makes it even more readily able to transfer energy between the electron-rich amides. This work both unveils a highly fluorescent AIE PA system design and sheds insights into the molecular orientation and packing design traits that can significantly enhance AIE in self-assembling systems.

A Single Set of Well-Designed Aptamer Probes for Reliable On-site Qualitative and Ultra-Sensitive Quantitative Detection

Aptamer-based probes are pivotal components in various sensing strategies, owing to their exceptional specificity and versatile programmable structure. Nevertheless, numerous aptamer-based probes usually offer only a single function, limiting their capacity to meet the diverse requirements of multi-faceted sensing systems. Here, we introduced supersandwich DNA probes (SSW-DNA), designed and modified on the outer surface of nanochannels with hydrophobic inner walls, enabling dual functionality: qualitative detection for on-site analysis and quantitative detection for precise analysis. The fragmented DNAs resulting from the target recognition, are subsequently identified through lateral flow assays, enabling robust on-site qualitative detection of microcystin-LR with an impressively low limit of detection (LOD) at 0.01 μg/L. Meanwhile, the nanochannels enable highly sensitive quantification of microcystin-LR through the current analysis, achieving an exceptionally low LOD at 2.5×10-7  μg/L, with a broad dynamic range spanning from 1×10-6 to 1×102  μg/L. Furthermore, the process of target recognition introduces just a single potential error propagation, which reduces the overall risk of errors during the entire qualitative and quantitative detection process. This sensing strategy broadens the scope of applications for aptamer-based composite probes, holding promising implications across diverse fields, such as medical diagnosis, food safety, and environmental protection.

Aggregation-Induced Emission Luminogens: A New Possibility for Efficient Visualization of RNA in Plants

RNAs play important roles in regulating biological growth and development. Advancements in RNA-imaging techniques are expanding our understanding of their function. Several common RNA-labeling methods in plants have pros and cons. Simultaneously, plants' spontaneously fluorescent substances interfere with the effectiveness of RNA bioimaging. New technologies need to be introduced into plant RNA luminescence. Aggregation-induced emission luminogens (AIEgens), due to their luminescent properties, tunable molecular size, high fluorescence intensity, good photostability, and low cell toxicity, have been widely applied in the animal and medical fields. The application of this technology in plants is still at an early stage. The development of AIEgens provides more options for RNA labeling. Click chemistry provides ideas for modifying AIEgens into RNA molecules. The CRISPR/Cas13a-mediated targeting system provides a guarantee of precise RNA modification. The liquid-liquid phase separation in plant cells creates conditions for the enrichment and luminescence of AIEgens. The only thing that needs to be looked for is a specific enzyme that uses AIEgens as a substrate and modifies AIEgens onto target RNA via a click chemical reaction. With the development and progress of artificial intelligence and synthetic biology, it may soon be possible to artificially synthesize or discover such an enzyme.

Solvent directed morphogenesis of a peptidic-benzimidazolium dipodal receptor: ratiometric detection and catalytic degradation of ochratoxin A

Ochratoxin A (OTA) is the most abundant and harmful toxin found in agriculture and processed food. The environment and human health are both harmed by this mycotoxin. As a result, in various scenarios, selective detection and biodegradation of ochratoxin A are essential. The current study reveals the morphogenesis of a peptidic-benzimidazolium dipodal receptor (SS4) and its application as a catalytic and sensing unit for the detection and degradation of OTA in an aqueous medium. Initially, a facile and scalable method was executed to synthesize SS4, and solvent-directed morphogenesis were examined under SEM analysis. Consequently, molecular recognition properties of self-assembled architectures were explored using UV-visible absorption, fluorescence spectroscopy, and atomic force microscopy (AFM). The designed probe showed a ratiometric response for OTA and served as a catalytic unit for the degradation of OTA at a short interval of 25 min. The biodegradation pathway for OTA was accomplished using LC-MS analysis. Furthermore, the reliability of the developed method was checked by determining the spiked concentrations of the OTA in cereals and wine samples. The results obtained are in good agreement with the % recovery and RSD values. The present work provides a robust, selective, and sensitive method of detection and degradation for OTA.

Genosensor on-chip paper for point of care detection: A review of biomedical analysis and food safety application

Over the last decade, paper-based biosensing has attracted considerable attention in numerous fields due to several advantages of them. To elaborate, using paper as a substrate of sensing approaches can be considered an affordable sensing approach owing to low cost of paper, and alongside that, the ability to operate without requiring external equipment. In many cases, cost-effective fabrication techniques such as screen printed and drop casting can be supposed as other benefits of these platforms. Despite the portability and affordability of paper-based assay, two important limitations including sensitivity and selectivity can decrease the application of these sensing approaches. Initially, decoration of paper substrate with nanomaterials (NMs) can improve the properties of paper due to high surface area and conductivity of them. Secondly, the presence of bioreceptors can provide a selective detection platform. Among different bioreceptors, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) can play a significant role. From this perspective, paper-based biosensors can be used for the detection of various gens which related to biomedical or food safety. In this review, we attempted to summarize recent trends and applications of paper-based genosensor, along with critical arguments in terms of NMs role in signal amplification. Furthermore, the lack of paper-based genosensors in field the of biomedical and food safety will be discussed in the following.

Fluorogenic Hyaluronan Nanogels Track Individual Early Protein Aggregates Originated under Oxidative Stress

Proteins are broadly versatile biochemical materials, whose functionality is tightly related to their folding state. Native folding can be lost to yield misfolded conformations, often leading to formation of protein oligomers, aggregates, and biomolecular phase condensates. The fluorogenic hyaluronan HA-RB, a nonsulfonated glycosaminoglycan with a combination of polyanionic character and of hydrophobic spots due to rhodamine B dyes, binds to early aggregates of the model protein cytoplasmic glyceraldehyde-3-phosphate dehydrogenase 1 from Arabidopsis thaliana (AtGAPC1) since the very onset of the oligomeric phase, making them brightly fluorescent. This initial step of aggregation has, until now, remained elusive with other fluorescence- or scattering-based techniques. The information gathered from nanotracking (via light-sheet fluorescence microscopy) and from FCS in a confocal microscope converges to highlight the ability of HA-RB to bind protein aggregates from the very early steps of aggregation and with high affinity. Altogether, this fluorescence-based approach allows one to monitor and track individual early AtGAPC1 aggregates in the size range from 10 to 100 nm with high time (∼10-2 s) and space (∼250 nm) resolution.

Biomimetic Structural Proteins: Modular Assembly and High Mechanical Performance

Protein-based biomaterials attract growing interests due to their encoded and programmable robust mechanical properties, superelasticity, plasticity, shape adaptability, excellent interfacial behavior, etc., derived from sequence-guided backbone structures, particularly compared to chemically synthetic counterparts in materials science and biomedical engineering. For example, protein materials have been successfully fabricated as (1) artificial implants (man-made tendons, cartilages, or dental tissues), due to programmable chemistry and biocompatibility; (2) smart biodevices with temperature/light-response and self-healing effects; and (3) impact resistance materials having great mechanical performance due to biomimetics. However, the existing method of regenerating protein materials from natural sources has two critical issues, low yield and structural damage, making it unable to meet demands. Therefore, it is crucial to develop an alternative strategy for fabricating protein materials. Heterologous expression of natural proteins with a modular assembly approach is an effective strategy for material preparation. Standardized, easy-to-assemble protein modules with specific structures and functions are developed through experimental and computational tools based on natural functional protein sequences. Through recombination and heterologous expression, these artificial protein modules become keys to material fabrication. Undergoing an assembly process similar to supramolecular self-assembly of proteins in cells, biomimetic modules can be fabricated for formation of macroscopic materials such as fibers and adhesives. This strategy inspired by synthetic biology and supramolecular chemistry is important for improving target protein yields and assembly integrity. It also preserves and optimizes the mechanical functions of structural proteins, accelerating the design and fabrication of artificial protein materials.In this Account, we overview recent studies on fabricating biomimetic protein materials to elucidate the concept of modular assembly. We discuss the design of biomimetic structural proteins at the molecular level, providing a wealth of details determining the bulk properties of materials. Additinally, we describe the modular self-assembly and assembly driven by inducing molecules, and mechanical properties and applications of resulting fibers. We used these strategies to develop fiber materials with high tensile strength, high toughness, and properties such as anti-icing and high-temperature resistance. We also extended this approach to design protein-based adhesives with ultra-strong adhesion, biocompatibility, and biodegradability for surgical applications such as wound sealing and healing. Other protein materials, including films and hydrogels, have been developed through chemical assembly routes. Finally, we describe exploiting synthetic biology and chemistry to overcome bottlenecks in structural protein modular design, biosynthesis, and material assembly and our perspectives for future development in structural biomaterials.

Molecular Design Strategy of Protein Isoform-Specific Fluorescent Probes by Considering Molecule in Its Entirety

Generally, different isoforms of proteins exert separate biological functions. However, due to similar structures and identical catalysis functions, distinguishing isoforms is challenging. Summarizing a molecular design strategy has great significance in developing a protein-specific fluorescent probe. Usually, recognition of a group was deemed to be the key to a protein isoform-specific response. However, some novel literature reported that fluorophore could play a vital role in the protein isoform-specific response. It means that any part of the fluorescent probe could affect the detected properties. In this work, we report the generation of the first probe to specifically recognize HexA(β-N-acetylhexosaminidase A), Hex-C4, by adjusting the length of the linker. Hex-C4 exhibits specific recognition of HexA both in vitro and in living cells. The integration of the fluorescent spectrum and the MD (molecular dynamics) results provide two factors for the molecular design of isoform-specific fluorescent probes. One is the interaction between tetraphenyl ethylene (AIE fluorogen) and amino acid residues, and the other is the interaction between amino acid residues and the binding group. In this work, a powerful tool to detect HexA in living cells is reported for the first time. Further, a workable molecular design strategy for protein isoform-specific fluorescent probes is summarized.

Self-assembled super-small AIEgen nanoprobe for highly sensitive and selective detection of protamine and trypsin

Amphiphilic aggregation-induced emission (AIE) molecules show superior potential for fabricating novel ultrasmall nanoprobes. Here, an anionic dipyridyl tetraphenylethene (TPE) derivative is rationally designed and a super-small self-assembled AIEgen nanoprobe (TPE-2Py-SO₃NaNPs, ca. 2.48 nm) is thus conveniently constructed for the supersensitive detection of protamine and trypsin. In HEPES/DMSO solution (8 : 2, v/v, pH = 7.4), negatively charged TPE-2Py-SO₃NaNPs exhibited an AIE effect in the presence of positively charged protamine, presenting a fluorescence enhancement at 498 nm together with a large Stokes shift of 150 nm and a low detection limit of 8.0 ng mL^-1. In addition, the in situ formed TPE-2Py-SO₃Na/protamine nanocomposite can be dissociated by trypsin due to the highly selective degradation of protamine via enzymatic hydrolysis, achieving a detection limit for trypsin as low as 5.0 ng mL^-1.

Smartphone conducted DNA portable quantitative detection platform based on photonic crystals chip and magnetic nanoparticles

It is of great significance to develop a highly sensitive and intuitive virus detection tool. A portable platform is constructed for quantitative detection of viral DNA based on the principle of fluorescence resonance energy transfer (FRET) between upconversion nanoparticles (UCNPs) and graphene oxide nanosheets (GOs) in this work. To implement a high sensitivity and low detection limit, GOs are modified by magnetic nanoparticles to prepare magnetic graphene oxide nanosheets (MGOs). Among them, the application of MGOs can not only eliminate the background interference, but also amplify the fluorescence intensity to a certain extent. Whereafter, a simple carrier chip based on photonic crystals (PCs) is introduced to realize a visual solid-phase detection, which also amplifies the luminescence intensity of the detection system. Finally, under the application of the 3D printed accessory and smartphone program of red-green-blue (RGB) evaluation, the portable detection can be completed simply and accurately. In a word, this work proposes a portable DNA biosensor with the triple functions of quantification, visualization and real-time detection can be used as a high-quality viral detection strategy and clinical diagnosis method.

AIEE-Active Flavones as a Promising Tool for the Real-Time Tracking of Uptake and Distribution in Live Zebrafish

In recent years, aggregation-induced emission enhancement (AIEE) molecules have shown great potential for applications in the fields of bio-detection, imaging, optoelectronic devices, and chemical sensing. Based on our previous studies, we investigated the fluorescence properties of six flavonoids and confirmed that compounds 1-3 have good aggregation-induced emission enhancement (AIEE) properties through a series of spectroscopic experiments. Compounds with AIEE properties have addressed the limitation imposed by the aggregation-caused quenching (ACQ) of classic organic dyes owing to their strong fluorescence emission and high quantum yield. Based on their excellent fluorescence properties, we evaluated their performance in the cell and we found that they could label mitochondria specifically by comparing their Pearson correlation coefficients (R) with Mito Tracker Red and Lyso-Tracker Red. This suggests their future application in mitochondrial imaging. Furthermore, studies of uptake and distribution characterization in 48 hpf zebrafish larvae revealed their potential for monitoring real-time drug behavior. The uptake of compounds by larvae varies significantly across different time cycles (between uptake and utilization in the tissue). This observation has important implications for the development of visualization techniques for pharmacokinetic processes and can enable real-time feedback. More interestingly, according to the data presented, tested compounds aggregated in the liver and intestine of 168 hpf larvae. This finding suggests that they could potentially be used for monitoring and diagnosing liver and intestinal diseases.

Spatial Confinement of Single-Drop System to Enhance Aggregation-Induced Emission for Detection of MicroRNAs

Due to high incidence, poor prognosis, and easy transformation into pancreatic cancer (PC) with high mortality, early diagnosis and prevention of acute pancreatitis (AP) have become significant research focuses. In this work, we proposed a magnetic single-drop microextraction (SDME) system with spatial confinement to enhance the aggregation-induced emission (AIE) effect for simultaneous fluorescence detection of miRNA-155 (associated with AP) and miRNA-196a (associated with PC). The target miRNAs were selectively recognized by the hairpin probe and triggered the DNA amplification reaction; then, the DNA strands with two independent probes of G-quadruplex/TAIN and Cy5 were constructed on the surfaces of the magnetic beads. The SDME process, in which a drop containing the fluorescence probes was formed at the tip of the magnetic microextraction rod rapidly within 10 s, was performed by magnetic extraction. In this way, G-quadruplex/TAIN was enriched owing to the spatial confinement of the single-drop system, and the fluorescence signal given off (by G-quadruplex/TAIN) was highly enhanced (AIE effect). This was detected directly by fluorescence spectrophotometry. The approach achieved low limits of detection of 2.1 aM for miRNA-196a and 8.1 aM for miRNA-155 and wide linear ranges from 10 aM to 10 nM for miRNA-196a and from 25 aM to 10 nM for miRNA-155. This novel method was applied to the fluorescence detection of miRNAs in human serum samples. High relative recoveries from 95.6% to 104.8% were obtained.

Platelet membrane camouflaged AIEgen-mediated photodynamic therapy improves the effectiveness of anti-PD-L1 immunotherapy in large-burden tumors

Although immunotherapy has achieved recent clinical success in antitumor therapy, it is less effective for solid tumors with large burdens. To overcome this challenge, herein, we report a new strategy based on platelet membrane-camouflaged aggregation-induced emission (AIE) luminogen (Plt-M@P) combined with the anti-programmed death ligand 1 (anti-PD-L1) for tumoral photodynamic-immunotherapy. Plt-M@P is prepared by using poly lactic-co-glycolic acid (PLGA)/PF3-PPh₃ complex as a nanocore, and then by co-extrusion with platelet membranes. PF3-PPh₃ is an AIE-active conjugated polyelectrolyte with photosensitizing capability for photodynamic therapy (PDT). Plt-M@P exhibits superior tumor targeting capacity in vivo. When applied in small tumor-bearing (~40 mm³) mice, Plt-M@P-mediated PDT significantly inhibits tumor growth. In tumor models with large burdens (~200 mm³), using Plt-M@P-mediated PDT or anti-PD-L1 alone is less effective, but the combination of both is effective in inhibiting tumor growth. Importantly, this combination therapy has good biocompatibility, as demonstrated by the absence of damage to the major organs, especially the reproductive system. In conclusion, we show that Plt-M@P-mediated PDT can improve anti-PD-L1 immunotherapy by enhancing antitumor effects, providing a promising strategy for the treatment of tumors with large burdens.

In Vivo Fluorescence Imaging-Guided Development of Near-Infrared AIEgens

In vivo fluorescence imaging has received extensive attention due to its distinguished advantages of excellent biosafety, high sensitivity, dual temporal-spatial resolution, real-time monitoring ability, and non-invasiveness. Aggregation-induced emission luminogens (AIEgens) with near-infrared (NIR) absorption and emission wavelengths are ideal candidate for in vivo fluorescence imaging for their large Stokes shift, high brightness and superior photostability. NIR emissive AIEgens provide deep tissue penetration depth as well as low interference from tissue autofluorescence. Here in this review, we summarize the molecular engineering strategies for constructing NIR AIEgens with high performances, including extending π-conjugation system and strengthen donor (D)-acceptor (A) interactions. Then the encapsulation strategies for increasing water solubility and biocompatibility of these NIR AIEgens are highlighted. Finally, the challenges and prospect of fabricating NIR AIEgens for in vivo fluorescence imaging are also discussed. We hope this review would provide some guidelines for further exploration of new NIR AIEgens.

A dual “turn-on” biosensor based on AIE effect and FRET for in situ detection of miR-125b biomarker in early Alzheimer's disease

MicroRNA-125b (miR-125b) is highly associated with synaptic dysfunction and tau hyperphosphorylation in the early pathogenesis of Alzheimer's disease (AD), making it a promising biomarker for early AD diagnosis. Hence, there is an urgent need for a reliable sensing platform to assist in situ miR-125b detection. In this work, we report a dual "turn-on" fluorescence biosensor based on the nanocomposite of aggregation-induced emission fluorogen (AIEgen)-labeled oligonucleotide (TPET-DNA) probes immobilized on the surface of cationic dextran modified molybdenum disulfide (TPET-DNA@Dex-MoS₂). In the presence of the target, TEPT-DNA can hybridize with miR-125b to form a DNA/RNA duplex, causing TPET-DNA to detach from the surface of Dex-MoS₂ that simultaneously activates the dual fluorescence enhancement processes: (1) recovery of TPET-DNA signal and (2) strong fluorescent emission from AIEgen triggered by restriction of the intramolecular rotation. The sensing performance of TPET-DNA@Dex-MoS₂ was demonstrated by detecting miR-125b in vitro with good sensitivity at the picomolar level and rapid response (≤1 h) without amplification procedures. Furthermore, our nanoprobes exhibited excellent imaging capabilities to aid real-time monitoring of the endogenous miR-125b in PC12 cells and brain tissues of mice AD model induced by local administration of okadaic acid (OA). The fluorescence signals of the nanoprobes indicated miR-125b was spatially associated with phosphorylated tau protein (p-tau) in vitro and in vivo. Therefore, TPET-DNA@Dex-MoS₂ could be a promising tool for in situ and real-time monitoring of the AD-related microRNAs and also provide mechanistic insight into the early prognosis of AD.

Fluorescence by self-assembly: autofluorescent peptide vesicles and fibers

A series of oxidized cysteinyl peptides ([P-Cys-X-OMe]₂; P = Boc or H; X = Trp or Glu) showed vesicular and fibrillar assemblies. The anatomy of the self-assembled vesicles from the water-soluble cystine peptide [Cys-Trp-OMe]₂ (1a) has been investigated by using various fluorescent probes such as ammonium 8-anilinonaphthalene-1-sulfonate, Nile Red and pyrene. The morphological characterization was carried out by fluorescence lifetime imaging microscopy (FLIM) and super resolution-structured illumination microscopy (SR-SIM) utilizing the autofluorescence of the vesicles stemming from the self-assembly. The self-assembled structures are also observed in solution as evident from the quantitative phase images obtained using a dual-mode digital holographic microscope (DHM) system. Present investigations show that the self-assembly is enthalpy- and entropy-driven in the aqueous medium. Based on the CD spectral studies, we proposed that 1a organizes into vesicles through the sequestration of indole units. We observed that the solutions of dipeptides 1a-b exhibit autofluorescence in the blue region upon excitation at a wavelength >350 nm. Detailed spectroscopic studies on the peptides lacking tryptophan 2a-b unequivocally showed that the autofluorescence stems exclusively from peptide aggregation. Our experimental results with appropriate controls revealed that the clustering of carbonyl chromophores is central to autofluorescence. Autofluorescence was also used to probe the vesicle formation without using any external fluorescent probe. To the best of our knowledge, this is the first report on autofluorescent vesicles formed by the spontaneous association of dipeptides. We also found that the vesicles formed by 1a can act as a host for guests like C₆₀. The biocompatibility and biodegradability of these peptides along with the autofluorescent nature and guest binding ability of peptide-based vesicles offer numerous applications in the biomedical area.

Fluorescence-Amplified Origami Microneedle Device for Quantitatively Monitoring Blood Glucose

Exploration of clinically acceptable blood glucose monitors has been engaging in the past decades, yet the ability to quantitatively detect blood glucose in a painless, accurate, and highly sensitive manner remains limited. Herein, a fluorescence-amplified origami microneedle (FAOM) device is described that integrates tubular DNA-origami nanostructures and glucose oxidase molecules into its inner network to quantitatively monitor blood glucose. The skin-attached FAOM device can collect glucose molecules in situ and transfer the input into a proton signal after the oxidase's catalysis. The proton-driven mechanical reconfiguration of DNA-origami tubes separates fluorescent molecules and their quenchers, eventually amplifying the glucose-correlated fluorescence signal. The function equation established on clinical examinees suggests that FAOM can report blood glucose in a highly sensitive and quantitative manner. In clinical blind tests, the FAOM achieves well-matched accuracy (98.70 ± 4.77%) compared with a commercial blood biochemical analyzer, fully meeting the requirements of accurate blood glucose monitoring. The FAOM device can be inserted into skin tissue in a trivially painful manner and with minimal leakage of DNA origami, substantially improving the tolerance and compliance of the blood glucose test.

Protease-Responsive Potential-Tunable AIEgens for Cell Selective Imaging of TMPRSS2 and Accurate Inhibitor Screening

Transmembrane protease serine 2 (TMPRSS2) is a plasma membrane protease that activates both spike protein of coronaviruses for cell entry and oncogenic signaling pathways for tumor progression. TMPRSS2 inhibition can reduce cancer invasion and metastasis and partially prevent the entry of SARS-CoV-2 into host cells. Thus, there is an urgent need for both TMPRSS2-selective imaging and precise screening of TMPRSS2 inhibitors. Here, we report a TMPRSS2-responsive surface-potential-tunable peptide-conjugated probe (EGTP) with aggregation-induced emission (AIE) features for TMPRSS2 selective imaging and accurate inhibitor screening. The amphiphilic EGTP was constructed with tunable surface potential and responsive efficiency with TMPRSS2 and its inhibitor. The rational construction of AIE luminogens (AIEgens) with modular peptides indicated that the cleavage of EGTP led to a gradual aggregation with bright fluorescence in high TMPRSS2-expressing cells. This strategy may have value for selective detection of cancer cells, SARS-CoV-2-target cells, and screening of protease inhibitors.

Designs and Applications of Multi-stimuli Responsive FRET Processes in AIEgen-Functionalized and Bi-fluorophoric Supramolecular Materials

Materials capable of displaying strong ratiometric fluorescence with Förster resonance energy transfer (FRET) processes have attracted much research interest because of various chemosensor and biomedical applications. This review highlights several popular strategies in designing FRET-OFF/ON mechanisms of ratiometric fluorescence systems. In particular, the developments of organic and polymeric FRET materials featuring aggregation-induced emission-based luminogens (AIEgens), supramolecular assemblies, photochromic molecular switches and surfactant-induced AIE/FRET mechanisms are presented. AIEgens have been frequently employed as FRET donor and/or acceptor fluorophores to obtain enhanced ratiometric fluorescences in solution and solid states. Since AIE effects and FRET processes rely on controllable distances between fluorophores, many interesting fluorescent properties can be designed by regulating aggregation states in polymers and supramolecular systems. Photo-switchable fluorophores, such as spiropyran and diarylethene, provide drastic changes in fluorescence spectra upon photo-induced isomerizations, leading to photo-switching mechanisms to activate/deactivate FRET processes. Supramolecular assemblies offer versatile platforms to regulate responsive FRET processes effectively. In rotaxane structures, the donor-acceptor distance and FRET efficiency can be tuned by acid/base-controlled shuttling of the macrocycle component. The tunable supramolecular interactions are strongly influenced by external factors (such as pH values, temperatures, analytes, surfactants, UV-visible lights, etc.), which induce the assembly and disassembly of host-guest systems and thus their FRET-ON/FRET-OFF behavior. In addition, the changes in donor or acceptor fluorescence profiles upon detections of analytes can also sufficiently alter the FRET behavior and result in different ratiometric fluorescence outputs. The strategies and examples provided in this review offer the insights and toolkits for future FRET-based material developments.

Preparation of oxime compound lipid droplet-specifically labeled fluorescent probe and its application in cell imaging

Fluorescent probes can facilitate our further comprehension of the functional and physiological roles of LDs and thus promote the development of effective therapeutic approaches. Oxime compounds are widely used due to their good crystallinity and high reactivity. However, the majority oximes fluorescent probes are usually employed for the detection of HCIO, and the application of oximes in fluorescently labeled LD_S is poorly reported. In this paper, three kinds of LDs fluorescent probes (NAP-a, NAP-b and NAP-c) with D-π-A structure were synthesized by simple synthesis method with 1,8-naphthalimide as fluorescent matrix and oxime group as electron donor. These probes were highly sensitive to polarity, and possessed good photostability and low cytotoxicity. Co-staining experiments showed that these probes could target LDs and the fluorescence image was green. These probes NAP-a, NAP-b and NAP-c possessed high Pearson coefficient (HeLa cells: 0.91, 0.95, 0.86) and Manders coefficient (HeLa cells: 0.91, 0.96, 0.86) with Nile Red. Interestingly, the dynamic variations in their size, shape and distribution could be clearly observed in the oleic acid-treated cell model of LDs. Imaging of zebrafish was performed and green fluorescence was collected in zebrafish. These excellent properties make oxime compound fluorescent probes a promising fluorescent probes for studying LDs and metabolic diseases. This study opens up a new way for the preparation of LDs fluorescent probe.

Protease-Responsive Peptide-Conjugated Mitochondrial-Targeting AIEgens for Selective Imaging and Inhibition of SARS-CoV-2-Infected Cells

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a serious threat to human health and lacks an effective treatment. There is an urgent need for both real-time tracking and precise treatment of the SARS-CoV-2-infected cells to mitigate and ultimately prevent viral transmission. However, selective triggering and tracking of the therapeutic process in the infected cells remains challenging. Here, we report a main protease (Mpro)-responsive, mitochondrial-targeting, and modular-peptide-conjugated probe (PSGMR) for selective imaging and inhibition of SARS-CoV-2-infected cells via enzyme-instructed self-assembly and aggregation-induced emission (AIE) effect. The amphiphilic PSGMR was constructed with tunable structure and responsive efficiency and validated with recombinant proteins, cells transfected with Mpro plasmid or infected by SARS-CoV-2, and a Mpro inhibitor. By rational construction of AIE luminogen (AIEgen) with modular peptides and Mpro, we verified that the cleavage of PSGMR yielded gradual aggregation with bright fluorescence and enhanced cytotoxicity to induce mitochondrial interference of the infected cells. This strategy may have value for selective detection and treatment of SARS-CoV-2-infected cells.

Programmable design and self assembly of peptide conjugated AIEgens for biomedical applications

Aggregation-induced emission luminogens (AIEgens) possess enhanced fluorescence in highly aggregated states, thus enabling AIEgens as a promising module for highly emissive fluorescence biomaterials. So far, AIEgens-based nanomaterials and their hybrids have been reported for biomedical applications. Benefiting from the intrinsic biocompatibility and biofunction-editing properties of peptides, peptide-AIEgens hybrid biomaterials reveal unlimited possibilities including target capacity, specificity, stimuli-responsiveness, self-assembly, controllable structural transformation, etc.. In the last two decades, peptide-AIEgens hybrid nanomaterials with a unique design concept in aggregated states have achieved various biomedical applications such as biosensing, bioimaging, imaging-guided surgery, drug delivery and therapy. More recently, programmable design of peptide-AIEgens for in situ self-assembly provides a unique strategy for constructing intelligent entities with defined biological functions. In this review, we summarize the basic design principle of programmable peptide-AIEgens, structure-effect relationship and their unusual biomedical effects. Finally, an outlook and perspective toward future challenges and developments of peptide-AIEgens nanomaterials are concluded.

Near-Infrared-Emissive AIE Bioconjugates: Recent Advances and Perspectives

Near-infrared (NIR) fluorescence materials have exhibited formidable power in the field of biomedicine, benefiting from their merits of low autofluorescence background, reduced photon scattering, and deeper penetration depth. Fluorophores possessing planar conformation may confront the shortcomings of aggregation-caused quenching effects at the aggregate level. Fortunately, the concept of aggregation-induced emission (AIE) thoroughly reverses this dilemma. AIE bioconjugates referring to the combination of luminogens showing an AIE nature with biomolecules possessing specific functionalities are generated via the covalent conjugation between AIEgens and functional biological species, covering carbohydrates, peptides, proteins, DNA, and so on. This perfect integration breeds unique superiorities containing high brightness, good water solubility, versatile functionalities, and prominent biosafety. In this review, we summarize the recent progresses of NIR-emissive AIE bioconjugates focusing on their design principles and biomedical applications. Furthermore, a brief prospect of the challenges and opportunities of AIE bioconjugates for a wide range of biomedical applications is presented.

Supramolecular self-assembly mediated aggregation-induced emission of fluorene-derived cyanostilbenes: multifunctional probes for live cell-imaging

The first discovery of aggregation-induced emission (AIE), whereby luminogen aggregation plays a positive role in enhancing the light-emission efficiency, has piqued the interest of many researchers as it opens up a new avenue for the exploration of practically beneficial luminescent materials. Diverse AIE-active luminogens (or AIEgens) with tunable emission colours and very high quantum yields (up to unity) in the solid state have been extensively utilised in a broad range of fields including optoelectronics, energy and bioscience. In this article, we describe novel fluorene-based fluorogens that exhibit bright emission in the solid-state, mechanical stimuli-responsive optical properties and aggregation-induced emissive ability, and were able to modulate their donor and acceptor properties. The target compounds were synthesized by a Knoevenagel condensation followed by Suzuki cross-coupling reaction, which tends to result in good yields. The target cyanostilbenes (4a-4d) show different reversibly switched states with high contrast through morphology modulation and demonstrate solvatochromic, vapochromic, and AIE properties. These results strongly suggest that compound 4d has better properties than the other derivatives (4a-c) due to the presence of extended donor-acceptor ability. Moreover, density-functional theory (DFT) calculations strongly support the UV-Vis and fluorescence spectral studies. The formation of nano-flakes and cuboid-shaped nanocrystals was further confirmed by FE-SEM and AFM studies. The synthesized compound 4d displayed very bright emission in the solid state and in the aggregate state as compared with the other derivatives (4a-4c). These results might be due to the presence of high-color contrast, which is an advantage for elucidation and overcomes the challenges exhibited in live-cell imaging applications. Moreover, an MTT assay on live A549 cells incubated with the target compound (4d) showed very low cytotoxicity even at high concentrations.

Structure of Self-assembled Peptide Determines the Activity of Aggregation-Induced Emission Luminogen-Peptide Conjugate for Detecting Alkaline Phosphatase

The unique property of turning on their fluorescence after aggregation or assembly makes aggregation-induced emission luminogens (AIEgens) ideal luminescent molecules for the construction of self-assembled peptide-based nanoprobes. However, the characteristic highly twisted or propeller-shaped molecular conformation of AIEgens tends to prevent the assembly of AIEgen-peptides. Here, we show that (i) the distance between tetraphenylethene (TPE) and assembled peptides should not be too far (less than five glycines), otherwise the self-assembly of peptides cannot limit the intramolecular rotation of conjugated TPE and the luminous efficiency of TPE-peptide to alkaline phosphatase (ALP) will decrease; (ii) properly increasing the number of amino acids with self-assembly ability (three phenylalanines) can improve their ALP-responsive self-assembly and luminescence ability; (iii) the strategy of co-assembly with a non-AIEgen-capped self-assembled peptide is a simple and effective way to realize the efficient assembly and luminescence of AIEgen-peptides; and (iv) the hydrophilic and hydrophobic balance of the probe should always be considered in the construction of an efficient AIEgen-peptide probe. In addition, AIEgen-peptide probes show good selectivity and sensitivity for ALP detection both in vitro and in live bacteria. These insights illustrated here are crucial for guiding the design of AIEgen-conjugated supramolecular materials, especially for the construction of AIEgen-peptides, for enzymes detection, biomarker imaging, diseases therapy, and other biomedical fields.

A fluorene based probe: Synthesis and "turn-on" water sensitivity of the in-situ formed Cu2+ complex: Application in bio-imaging

A new fluorene based probe (FTH) has been evaluated for its photo-physical properties in solution as well as in the aggregated state/viscous environment. Addition of a poor solvent (water) to the solution of the probe in a good (acetonitrile) solvent significantly enhanced the otherwise weak emission due to aggregation induced emission (AIE). The emission enhancement is also related to the increase in viscosity of the solution, leading to the restricted intramolecular rotation of the peripheral (phenyl) groups. Interestingly, the emission behaviour of the non-emissive in-situ formed Cu²⁺ complex is drastically modulated in the presence of water. The solution of the putative Cu²⁺ complex of the probe turns highly emissive (yellow colour) upon addition of a small fraction of water (up to 7.6 wt %), but the yellow emission diminishes upon increasing higher water fraction. We propose that the initially formed Cu²⁺ complex undergoes hydrolysis in the presence of higher water content releasing the free amine possessing the diaryl amino rotors thus rendering the solution non-emissive. Thus the current probe being reported herein discloses its potential to generate trace water sensitive turn-on Cu²⁺ complex. Additionally, the bio-imaging potential of FTH for live cancer cells and its sensitivity towards intracellular presence of Cu²⁺ ions has been demonstrated.

Dramatic Emission Enhancement of Aggregation-Induced Emission Luminogens by Dynamic Metal Coordination Bonds and Anti-Heavy-Atom Effect

Restriction of intramolecular motions of AIEgens is greatly intensified by introducing dynamic metal coordination bonds to achieve dramatic fluorescence enhancement, which provides a simple and effective way to dramatically improve...

Novel Pyrazine-Bridged D-A-D Type Charge Neutral Probe for Membrane Permeable Long-Term Live Cell Imaging

A novel donor-acceptor-donor (D-A-D) type compound containing pyrazine as the acceptor and triphenylamine as the donor has been designed and synthesized. The photophysical properties and biocompatibility of this probe, namely (OMeTPA)2-Pyr for live cell imaging were systematically investigated, with observed large Stokes shifts, high photostability, and low cytotoxicity. Furthermore, we demonstrated that (OMeTPA)2-Pyr could permeate live cell membranes for labeling. The proposed mechanism of this probe was the binding and shafting through membrane integral transport proteins by electrostatic and hydrophobic interactions. These salient and novel findings can facilitate the strategic design of new pyrazine-fused charge-neutral molecular platforms as fluorescent probes, for long-term in situ dynamic monitoring in live cells.

Tunning Intermolecular Interaction of Peptide-Conjugated AIEgen in Nano-Confined Space for Quantitative Detection of Tumor Marker Secreted from Cells

Determining the expression level of biomarkers is crucial for disease diagnosis. However, the low abundance of biomarkers in the early stage makes the detection extremely difficult by traditional aggregation-induced emission (AIE)-based fluorescent probes. Here, by tuning the intermolecular interaction, a two steps-based MP/NPs-SLIPS sensing system is designed for ultrasensitive detection of the tumor marker matrix metalloproteinase-2 (MMP-2). During the sensing process, aggregation of AIE residual could be intensified through the electrostatic absorption by negatively charged nanoparticles (NPs), as well as the confined space formed by the self-assembly of NPs to photonic crystals (PCs) on slippery lubricant-infused porous substrates (SLIPS). The fluorescent signals obviously increased with a strengthened aggregation degree, which contributes to improved sensitivity. Thus, the limit of detection is decreased to 3.7 ng/mL for MP/NPs-SLIPS sensing system, which could be used for detecting the MMP-2 secreted by tumor cells directly. This strategy also demonstrated its potential applications as high-throughput detection devices and will be of significance for the ultrasensitive analysis of biomarkers.

Aggregation-Induced Emission Luminogens with Photoresponsive Behaviors for Biomedical Applications

Fluorescent biomedical materials can visualize subcellular structures and therapy processes in vivo. The aggregation-induced emission (AIE) phenomenon helps suppress the quenching effect in the aggregated state suffered by conventional fluorescent materials, thereby contributing to design strategies for fluorescent biomedical materials. Photoresponsive biomedical materials have attracted attention because of the inherent advantages of light; i.e., remote control, high spatial and temporal resolution, and environmentally friendly characteristics, and their combination with AIE facilitates development of fluorescent molecules with efficient photochemical reactions upon light irradiation. In this review, organic compounds with AIE features for biomedical applications and design strategies for photoresponsive AIE luminogens (AIEgens) are first summarized briefly. Applications are then reviewed, with the employment of photoresponsive and AIE-active molecules for photoactivation imaging, super-resolution imaging, light-induced drug delivery, photodynamic therapy with photochromic behavior, and bacterial targeting and killing being discussed at length. Finally, the future outlook for AIEgens is considered with the aim of stimulating innovative work for further development of this field.

AIEgen-Based Lifetime-Probes for Precise Furin Quantification and Identification of Cell Subtypes

Biochemical sensing probes based on aggregation-induced-emission luminogens (AIEgens) are widely used in biological imaging and therapy, chemical sensing, and material sciences. However, it is still a great challenge to quantify the targets through fluorescence intensity of AIEgen probes due to their undesirable aggregations. Here, a PyTPA-ZGO probe with three lifetime signals for precise quantification of furin is constructed: the lifetime signal 1 and signal 2 comes from AIEgen PyTPA-P (τ_Pn ) and inorganic nanoparticles Zn₂ GeO₄ :Mn²⁺ -NH₂ (τ_Zn ), respectively, while the lifetime signal 3 is marked as the composite dual-lifetime signal (CDLS_n , C D L S n = τ Z n τ P n ). In contrast, the fluorescence intensity signal of PyTPA-P shows defectively quantitative performance. Furthermore, it is found that the CDLS_n exhibits higher significant differences than the two other lifetime signals (τ_Pn and τ_Zn ) thanks to its wide range between the maximum and minimum signal values and small standard deviation. Therefore, CDLS_n is further used to accurately identify cell subtypes based on the specific concentration of furin in each subtype. The lifetime criterion can realize precise quantification, and it should be a promising direction of AIEgen-based quantitative analysis in the future.

Triboelectric Nanogenerator-Based Sensor Systems for Chemical or Biological Detection

The rapid advances in the Internet of things and wearable devices have created a massive platform for sensor systems that detect chemical or biological agents. The accelerated development of these devices in recent years has simultaneously aggravated the power supply problems. Triboelectric nanogenerators (TENGs) represent a thriving renewable energy technology with the potential to revolutionize this field. In this review, the significance of TENG-based sensor systems in chemical or biological detection from the perspective of the development of power supply for biochemical sensors is discussed. Further, a range of TENGs are classified according to their roles as power supplies and/or self-powered active sensors. The TENG powered sensor systems are further discussed on the basis of their framework and applications. The working principles and structures of different TENG-based self-powered active sensors are presented, along with the classification of the sensors based on these factors. In addition, some representative applications are introduced, and the corresponding challenges are discussed. Finally, some perspectives for the future innovations of TENG-based sensor systems for chemical/biological detection are discussed.

Boosting Photoacoustic Effect via Intramolecular Motions Amplifying Thermal-to-Acoustic Conversion Efficiency for Adaptive Image-Guided Cancer Surgery

Photoacoustic (PA) imaging emerges as a promising technique for biomedical applications. The development of new strategies to boost PA conversion without depressing other properties (e.g., fluorescence) is highly desirable for multifunctional imaging but difficult to realize. Here, we report a new phenomenon that active intramolecular motions could promote PA signal by specifically increasing thermal-to-acoustic conversion efficiency. The compound with intense intramolecular motion exhibits amplified PA signal by elevating thermal-to-acoustic conversion, and the fluorescence also increases due to aggregation-induced emission signature. The simultaneously high PA and fluorescence brightness of TPA-TQ3 NPs enable precise image-guided surgery. The preoperative fluorescence and PA imaging are capable of locating orthotopic breast tumor in a high-contrast manner, and the intraoperative fluorescence imaging delineates tiny residual tumors. This study highlights a new design guideline of intramolecular motion amplifying PA effect.

Rational design of pyrrole derivatives with aggregation-induced phosphorescence characteristics for time-resolved and two-photon luminescence imaging

Pure organic room-temperature phosphorescent (RTP) materials have been suggested to be promising bioimaging materials due to their good biocompatibility and long emission lifetime. Herein, we report a class of RTP materials. These materials are developed through the simple introduction of an aromatic carbonyl to a tetraphenylpyrrole molecule and also exhibit aggregation-induced emission (AIE) properties. These molecules show non-emission in solution and purely phosphorescent emission in the aggregated state, which are desirable properties for biological imaging. Highly crystalline nanoparticles can be easily fabricated with a long emission lifetime (20 μs), which eliminate background fluorescence interference from cells and tissues. The prepared nanoparticles demonstrate two-photon absorption characteristics and can be excited by near infrared (NIR) light, making them promising materials for deep-tissue optical imaging. This integrated aggregation-induced phosphorescence (AIP) strategy diversifies the existing pool of bioimaging agents to inspire the development of bioprobes in the future.

DNA-templated control of chirality and efficient energy transport in supramolecular DNA architectures with aggregation-induced emission

Two conjugates of tetraphenylethylene with d-2′-deoxyuridine (1d) and l-2′-deoxyuridine (1l) were synthesized to construct new supramolecular DNA-architectures by self-assembly. The non-templated assemblies of 1d and 1l show strong aggregation-induced emission and their chirality is exclusively controlled by the configuration of their sugar part. In contrast, the chirality of the DNA-templated assemblies is governed by the configuration of the DNA, and there is no configuration-selective binding of 1d to d-A₂₀ and 1l to l-A₂₀. The quantum yield of the assembly of 1d along the single-stranded DNA A₂₀ is 0.40; approximately every second available binding site on the DNA template is occupied by 1d. The strong aggregation-induced emission of these DNA architectures can be efficiently quenched and the excitation energy can be transported to Atto dyes at the 5′-terminus. A multistep energy transport “hopping” precedes the final energy transfer to the terminal acceptor. The building block 1d promotes this energy transport as stepping stones. This was elucidated by reference DNA double strands in which 1d was covalently incorporated at two distinct sites in the sequences, one near the Atto dye, and one farther away. This new type of completely self-assembled supramolecular DNA architecture is hierarchically ordered and the DNA template controls not only the binding but also the energy transport properties. The high intensity of the aggregation-induced emission and the excellent energy transport properties make these DNA-based materials promising candidates for optoelectronic applications.

DNA architectures with tetraphenylethylene are assembled in a non-covalent way. The strong aggregation-induced emission of the chromophores is quenched and the energy is transported to Atto dyes by a multistep energy “hopping”.

Two-Color Visualization of Cholesterol Fluctuation in Plasma Membranes by Spatial Distribution-Controllable Single Fluorescent Probes

Visualizing cholesterol (CL) fluctuation in plasma membranes is a crucially important yet challenging task in cell biology. Here, we proposed a new imaging strategy based on permeability changes of plasma membranes triggered by different CL contents to result in controllable spatial distribution of single fluorescent probes (SF-probes) in subcellular organelles. Three spatial distribution-controllable SF-probes (PMM-Me, PMM-Et, and PMM-Bu) for imaging CL fluctuation in plasma membranes were rationally developed. These SF-probes target plasma membranes and mitochondria at normal CL levels, while they display solely staining in plasma membranes and mitochondria at increased and decreased CL levels, respectively. These polarity-sensitive probes also show distinct emission colors with fluorescence peaks of 575 and 620 nm in plasma membranes and mitochondria, respectively. Thus, the CL fluctuation in plasma membranes can be clearly visualized by means of the spatially distributed and two-color emissive SF-probes.

Aggregation-induced emission luminogens reveal cell cycle-dependent telomerase activity in cancer cells

Telomerase acts as an important biomarker for tumor identification, and synthesizes telomeric repeats at the end of chromosome telomeres during the replicative phase of the cell cycle; thus, the expression level of telomerase changes as the cell cycle progresses. TERT mRNA expression and telomerase activity were significantly increased in over 80% of human cancers from tissue specimens. Although many efforts have been made in detecting the activity of TERT mRNA and active telomerase, the heterogeneous behavior of the cell cycle was overlooked, which might affect the accuracy of the detection results. Herein, the AIEgen-based biosensing systems of PyTPA-DNA and Silole-R were developed to detect the cellular level of TERT mRNA and telomerase in different cell cycles. As a result, the fluorescence signal of cancer cells gradually increased from G0/G1, G1/S to S phase. In contrast, both cancer cells arrested at G2/M phase and normal cells exhibited negligible fluorescence intensities. Compared to normal tissues, malignant tumor samples demonstrated a significant turn-on fluorescence signal. Furthermore, the transcriptomics profiling revealed that tumor biomarkers changed as the cell cycle progressed and biomarkers of CA9, TK1 and EGFR were more abundantly expressed at early S stage. In this vein, our study presented advanced biosensing tools for more accurate analysis of the cell-cycle-dependent activity of TERT mRNA and active telomerase in clinical tissue samples.

Trapping endoplasmic reticulum with amphiphilic AIE-active sensor via specific interaction of ATP-sensitive potassium (KATP)

The current aggregation-induced emission luminogens (AIEgens) sometimes suffer from poor targeting selectivity due to undesirable aggregation in the hydrophilic biosystem with 'always-on' fluorescence or unspecific aggregation in the lipophilic organelle with prematurely activated fluorescence. Herein, we report an unprecedented 'amphiphilic AIEgen' sensor QM-SO3-ER based on the AIE building block of quinoline-malononitrile (QM). The introduced hydrophilic sulfonate group can well control the specific solubility in a hydrophilic system with desirable initial 'fluorescence-off' state. Moreover, the incorporated p-toluenesulfonamide group plays two roles: enhancing the lipophilic dispersity, and behaving as binding receptor to the adenosine triphosphate (ATP)-sensitive potassium (KATP) on the endoplasmic reticulum (ER) membrane to generate the docking assay confinement effect with targetable AIE signal. The amphiphilic AIEgen has for the first time settled down the predicament of unexpected 'always-on' fluorescence in the aqueous system and the untargetable aggregation signal in the lipophilic organelle before binding to ER, thus successfully overcoming the bottleneck of AIEgens' targetability.

Two-Photon Near-Infrared AIE Luminogens as Multifunctional Gene Carriers for Cancer Theranostics

Construction of multifunctional nonviral gene vectors to execute defined tasks holds great potential for the precise and effective treatment of gene-associated diseases. Herein, we have developed four large π-conjugation triphenylamine derivatives bearing two polar [12]aneN₃ heads and a lipophilic tail for applications in gene delivery, one/two-photon-triggered near-infrared (NIR) fluorescence bioimaging, and combined photodynamic therapy (PDT) and gene therapy of cancer. These compounds possess typical NIR aggregation-induced emission characteristics, mega Stokes shifts, strong two-photon excitation fluorescence, and excellent DNA condensation abilities. Among them, vector 4 with a tail of n-hexadecane realized a transfection efficiency as high as 6.7 times that of the commercial transfection agent Lipofectamine 2000 in HEK293T cell lines. Using vector 4 as an example, transfection process tracking and ex vivo/in vivo tumoral imaging and retention with high resolution, high brightness, deep tissue penetration, and good biosafety were demonstrated. In addition, efficient singlet oxygen (¹O₂) generation by the DNA complex formed by vector 4 (4/DNA) resulted in effective PDT. Combined with anticancer gene therapy, collaborative cancer treatment with a dramatically enhanced cancer cell-killing effect was achieved. The development of this "three birds, one stone" approach suggests a new and promising strategy for better cancer treatment and real-time tracking of gene delivery.