Overview of the Design and Application of Photothermal Immunoassays.

Developing powerful immunoassays for sensitive and real-time detection of targets has always been a challenging task. Due to their advantages of direct readout, controllable sensing, and low background interference, photothermal immunoassays have become a type of new technology that can be used for various applications such as disease diagnosis, environmental monitoring, and food safety. By modification with antibodies, photothermal materials can induce temperature changes by converting light energy into heat, thereby reporting specific target recognition events. This article reviews the design and application of photothermal immunoassays based on different photothermal materials, including noble metal nanomaterials, carbon-based nanomaterials, two-dimensional nanomaterials, metal oxide and sulfide nanomaterials, Prussian blue nanoparticles, small organic molecules, polymers, etc. It pays special attention to the role of photothermal materials and the working principle of various immunoassays. Additionally, the challenges and prospects for future development of photothermal immunoassays are briefly discussed.

Aggregation-induced emission-based competitive immunoassays for "signal-on" detection of proteins with multifunctional metal-organic frameworks as signal tags.

An aggregation-induced emission (AIE)-based strategy was proposed for fluorescence immunoassays of protein biomarkers using Cu-based metal-organic frameworks (Cu-MOFs) to load recombinant targets and enzymes for dual signal amplification. The immunosensing platform was built based on the sequestration and consumption of the substrates of pyrophosphate (PPi) ions by Cu-MOFs and enzymatic catalysis. The negatively charged PPi could trigger the aggregation of positively charged tetraphenylethene (TPE)-substituted pyridinium salt nanoparticles (TPE-Py NPs) by electrostatic interactions, lighting up the fluorescence due to the AIE phenomenon. The consumption of PPi by the captured Cu-MOFs through the Cu2+-PPi chelation interaction and ALP-enzymatic hydrolysis depressed the aggregation of TPE-Py NPs. Capture of the tested targets in samples by the antibodies on the plate surface could prevent the attachment of target/ALP-loaded Cu-MOFs due to the competitive immunoreactions. The "signal-on" competitive immunoassay was applied for the detection of procalcitonin (PCT) as the model analyte with a linear range of 0.01-10 pg/mL and a detection limit down to 8 pg/mL. The conceptual integration of AIE with enzymatic and MOFs-based dual signal amplification endowed fluorescence immunoassays with high sensitivity and selectivity. The surface modification of Cu-MOFs with hexahistine (His6)-tagged recombinant proteins through metal coordination interactions should be evaluable for the design of novel biosensors.

Enhancing Biocatalysis through Chiral Supramolecular Scaffolds: Insights into the Structural Adaptability of Lipase.

How to maintain high catalytic activity and stability in the process of biocatalysis is crucial, inspiring strategies to construct an appropriate catalytic microenvironment. Considering the lipase's inherent chirality and the necessity for a delicate hydrophilic-hydrophobic equilibrium, we crafted a chiral, nonaqueous catalytic microenvironment via the in situ coassembly of Boc-FLFL-NHNH2 (Bfl) and lipase. Benefiting from the chirality and distinct Bfl-lipase interactions, the lipase@Bfl supramolecular hybrid amplifies biological functionalities and can serve as a versatile and highly efficient catalyst. Kinetic investigations and molecular docking simulations uncover the strong lipase-substrate affinity and lipase-Bfl interactions, explaining the enhanced biological effects, catalytic activity, and stability. Our study establishes a suitable microenvironment to address the chirality and hydrophobicity during catalysis and highlights the potential of artificial chiral scaffolds and catalytic medium for enhancing lipase activity.

Supramolecular Polymer Co-Assembled Multifunctional Chiral Hybrid Hydrogels with Adhesive, Self-Healing and Antibacterial Properties.

Amino acid-derived self-assembled nanofibers comprising supramolecular chiral hydrogels with unique physiochemical characteristics are highly demanded biomaterials for various biological applications. However, their narrow functionality often limits practical use, necessitating the development of biomaterials with multiple features within a single system. Herein, chiral co-assembled hybrid hydrogel systems termed LPH-EGCG and DPH-EGCG were constructed by co-assembling L/DPFEG gelators with epigallocatechin gallate (EGCG) followed by cross-linking with polyvinyl alcohol (PVA) and hyaluronic acid (HA). The developed hybrid hydrogels exhibit superior mechanical strength, self-healing capabilities, and adhesive properties, owing to synergistic non-covalent interactions. Integrating hydrophilic polymers enhances the system's capacity to demonstrate favorable swelling characteristics. Furthermore, the introduction of EGCG facilitated the hybrid gels to display notable antibacterial properties against both Gram-positive and Gram-negative bacterial strains, alongside showcasing strong antioxidant capabilities. In vitro investigation demonstrated enhanced cell adhesion and migration with the LPH-EGCG system in comparison to DPH-EGCG, thus emphasizing the promising prospects of these hybrid hydrogels in advanced tissue engineering applications.

Optical Bioassays Based on the Signal Amplification of Redox Cycling.

Optical bioassays are challenged by the growing requirements of sensitivity and simplicity. Recent developments in the combination of redox cycling with different optical methods for signal amplification have proven to have tremendous potential for improving analytical performances. In this review, we summarized the advances in optical bioassays based on the signal amplification of redox cycling, including colorimetry, fluorescence, surface-enhanced Raman scattering, chemiluminescence, and electrochemiluminescence. Furthermore, this review highlighted the general principles to effectively couple redox cycling with optical bioassays, and particular attention was focused on current challenges and future opportunities.

Overview on the Development of Electrochemical Immunosensors by the Signal Amplification of Enzyme- or Nanozyme-Based Catalysis Plus Redox Cycling.

Enzyme-linked electrochemical immunosensors have attracted considerable attention for the sensitive and selective detection of various targets in clinical diagnosis, food quality control, and environmental analysis. In order to improve the performances of conventional immunoassays, significant efforts have been made to couple enzyme-linked or nanozyme-based catalysis and redox cycling for signal amplification. The current review summarizes the recent advances in the development of enzyme- or nanozyme-based electrochemical immunosensors with redox cycling for signal amplification. The special features of redox cycling reactions and their synergistic functions in signal amplification are discussed. Additionally, the current challenges and future directions of enzyme- or nanozyme-based electrochemical immunosensors with redox cycling are addressed.

Assessing safety and efficacy of microscopic and laparoscopic varicocoelectomy for varicocoele treatment: A comparative cohort study.

BACKGROUND: Surgical is appropriate for 35-40% of varicocoele-induced infertility. This comparative observational study presents a comparative assessment of microscopic or laparoscopic varicocoelectomy (grade II varicocoele; n = 132 cases). METHODS: Sperm count, density, total motility, and forward motility rate (preoperative and postoperative 6 months), operation duration, pain at 1 month, testicular atrophy (by scrotal ultrasound at 3 months), recurrence (angiography at 6 months), and scrotal edema (at 12 months) were measured. RESULTS: The preoperative semen parameters were comparable between groups (P > 0.05), as were certain postoperative results (total sperm count [median 162 (range 100-242) compared with median 182 (range 84-253)]; sperm density [median 47 (range 38-83) compared with median 42 (range 27-88)]; forward motility (37.18 ± 4.14 compared with 34.13 ± 7.79); P > 0.05). However, sperm motility was higher in the microscope group (52.79 ± 8.21 compared with 46.64 ± 10.04; t = 2.304, P = 0.040). Within the microscope group, postoperative sperm density [median 47 (range 38-83)], total sperm motility (53.79 ± 8.25), and forward motility sperm rate (37.19 ± 4.14) demonstrated significant improvements compared with preoperative values (Z = -2.679, P = 0.005; t = -4.548, P < 0.001; t = -5.029, P < 0.001). In contrast, the postoperative forward motility sperm rate (34.13 ± 7.78) displayed substantial improvements compared with preoperative values (27.74 ± 14.42) within the laparoscopic group (t = -3.895, P = 0.001). Testicular atrophy occurred in neither group. CONCLUSIONS: Microscopic varicocoelectomy may be safer and more effective.

Aggregation-induced emission for the detection of peptide ligases with improving ligation efficiency.

BACKGROUND: Monitoring peptide ligase activity is of great significance for biological research, medical diagnosis, and drug discovery. The current methods for the detection of peptide ligases suffer from the limitations of high background signal, elaborate design of substrate, and high reversibility of ligation reaction. In this work, we proposed a simple and sensitive method for ligase detection with reducing ligation reversibility on the basis of aggregation-induced emission (AIE) mechanism. RESULTS: The peptide probes labeled with AIE luminogens (AIEgens) were water-soluble and emitted weak fluorescence. After ligation reaction, the enzymatic products with AIEgens showed high hydrophobicity and could readily assembly into aggregates, thus lighting up the fluorescence. More interestingly, the formation of aggregates pushed the equilibrium to the generation of the desired ligation products, thus improving the catalytic efficiency by driving the reaction towards completion. The ligation reaction conversion rate (>80 %) is significantly higher than that without blocking the reversibility with additional treatment. With sortase A (SrtA) as the analyte example, the detection limit of this method was found to be 0.01 nM with a linear range of 0-50 nM. The system was applied to evaluate the inhibition efficiency of berberine chloride and quercetin and determine the activity of SrtA in serum, lysate and Staphylococcus aureus with satisfactory results. SIGNIFICANCE: This study indicated that the ligation efficiency and detection sensitivity can be improved by reducing ligation reversibility through AIE phenomenon. The proposed strategy could be used for the detection of other peptide ligases by adopting sequence-specific peptide substrates.

Stimuli-responsive aggregation-induced emission of molecular probes by electrostatic and hydrophobic interactions: Effect of organic solvent content and application for probing of alkaline phosphatase activity.

We suggest that aggregation-induced emission (AIE) molecular probes with single charged/reactive group can exist in the formation of nanostructures but not monomers at extremely low organic solvent content. The nanoaggregates show good dispersivity and emit week emission. Stimuli-responsive assembly of nanoaggregates by electrostatic interactions can turn on the fluorescence, facilitating the design of biosensors with single-charged molecular probes as the AIE fluorogens. To prove the concept, tetraphenylethene-substituted pyridinium salt (TPE-Py) was used as the AIE fluorogen for probing of alkaline phosphatase (ALP) activity with pyrophosphate ion (PPi) as the enzyme substrate. The dynamic light scattering and transmission electron microscope experiments demonstrated that TPE-Py probes existed in aqueous solution at nanometer size and morphology. Stimuli such as the negatively charged PPi, citrate, ATP, ADP, NADP and DNA could trigger the aggregation of the positively charged TPE-Py nanoparticles, thus enhancing the fluorescence via AIE effect. ALP-enzymatic hydrolysis of PPi into two phosphate ions (Pi) limited the aggregation of TPE-Py nanoparticles. The strategy was used for the assay of ALP with a low detection limit (1 U/L) and wide linear range (1-200 U/L). We also investigated the effect of organic solvent content on the AIE process and found that high concentration of organic solvent can prevent the hydrophobic interaction between AIE molecules but show no essential influence on the electrostatic interaction-mediated assembly. The work should be evaluable for understanding AIE phenomenon and developing novel, simple and sensitive biosensors using a molecular probe with single charged/reactive group as the signal reporter.

Streptavidin-Conjugated DNA for the Boronate Affinity-Based Detection of Poly(ADP-Ribose) Polymerase-1 with Improved Sensitivity.

This work reports the development of a fluorescence method for the detection of poly(ADP-ribose) polymerase-1 (PARP1), in which a phenylboronic acid-modified fluorescein isothiocyanate dye (FITC-PBA) was used to recognize the formed poly(ADP-ribose) (PAR) polymer. The detection system was designed by conjugating recombinant streptavidin (rSA) with PARP1-specific double-stranded DNA (dsDNA) through streptavidin-biotin interaction. Capture of PARP1 via rSA-biotin-dsDNA allowed for the poly-ADP-ribosylation (PARylation) of both rSA and PARP1 in a homogeneous solution. The resulting rSA-biotin-dsDNA/PAR conjugates were then captured and separated via the commercialized nitrilotriacetic acid-nickel ion-modified magnetic bead (MB-NTA-Ni) through the interaction between NTA-Ni on MB surface and oligohistidine (His6) tag in rSA. The PAR polymer could capture the dye of FITC-PBA through the borate ester interaction between the boronic acid moiety in PBA and the cis-diol group in ribose, thus causing a decrease in fluorescence signal. The PARylation of streptavidin and the influence of steric hindrance on PARylation efficiency were confirmed using reasonable detection strategies. The method showed a wide linear range (0.01~20 U) and a low detection limit (0.01 U). This work should be valuable for the development of novel biosensors for the detection of poly(ADP-ribose) polymerases and diol-containing species.

Background-Quenched Aggregation-Induced Emission through Electrostatic Interactions for the Detection of Poly(ADP-ribose) Polymerase-1 Activity.

Poly(ADP-ribose) polymerase-1 (PARP1) is a potential biomarker and therapeutic target for cancers that can catalyze the poly-ADP-ribosylation of nicotinamide adenine dinucleotide (NAD+) onto the acceptor proteins to form long poly(ADP-ribose) (PAR) polymers. Through integration with aggregation-induced emission (AIE), a background-quenched strategy for the detection of PARP1 activity was designed. In the absence of PARP1, the background signal caused by the electrostatic interactions between quencher-labeled PARP1-specitic DNA and tetraphenylethene-substituted pyridinium salt (TPE-Py, a positively charged AIE fluorogen) was low due to the fluorescence resonance energy transfer effect. After poly-ADP-ribosylation, the TPE-Py fluorogens were recruited by the negatively charged PAR polymers to form larger aggregates through electrostatic interactions, thus enhancing the emission. The detection limit of this method for PARP1 detection was found to be 0.006 U with a linear range of 0.01~2 U. The strategy was used to evaluate the inhibition efficiency of inhibitors and the activity of PARP1 in breast cancer cells with satisfactory results, thus showing great potential for clinical diagnostic and therapeutic monitoring.

Three-electrode germanium-on-silicon avalanche photodiode array.

In this Letter, we report a bridge-connected three-electrode germanium-on-silicon (Ge-on-Si) avalanche photodiode (APD) array compatible with the complementary metal-oxide semiconductor (CMOS) process. In addition to the two electrodes on the Si substrate, a third electrode is designed for Ge. A single three-electrode APD was tested and analyzed. By applying a positive voltage on the Ge electrode, the dark current of the device can be reduced, and yet the response of the device can be increased. Under a dark current of 100 nA, as the voltage on Ge increases from 0 V to 15 V, the light responsivity is increased from 0.6 A/W to 1.17 A/W. We report, for the first time to the best of our knowledge, the near-infrared imaging properties of an array of three-electrode Ge-on-Si APDs. Experiments show that the device can be used for LiDAR imaging and low-light detection.

Mxene-Based Supramolecular Composite Hydrogels for Antioxidant and Photothermal Antibacterial Activities.

Bacterial infections and oxidative damage caused by various reactive oxygen species (ROS) pose a significant threat to human health. It is highly desirable to find an ideal biomaterial system with broad spectrum antibacterial and antioxidant capabilities. A new supramolecular antibacterial and antioxidant composite hydrogel made of chiral L-phenylalanine-derivative (LPFEG) as matrix and Mxene (Ti3 C2 Tx ) as filler material is presented. The noncovalent interactions (H-bonding and π-π interactions) in between LPFEG and Mxene and the inversion of LPFEG chirality are verified by Fourier transform infrared and circular dichroism spectroscopy. The composite hydrogels show improved mechanical properties revealed by rheological analysis. The composite hydrogel system exhibits photothermal conversion efficiency (40.79%), which enables effective photothermal broad-spectrum antibacterial activities against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria. Furthermore, the Mxene also enables the composite hydrogel to exhibit excellent antioxidant activity by efficiently scavenging free radicals like DPPH•, ABTS•+, and •OH. These results indicate that the Mxene-based chiral supramolecular composite hydrogel, with improved rheological, antibacterial, and antioxidant properties has a great potential for biomedical applications.

Development and validation of the Chinese version of the self-management support scale for kidney transplant recipients.

BACKGROUND: Providing self-management support to kidney transplant recipients is essential. However, a scale to identify the self-management support they have received is lacking. The purpose of this study is to develop a Self-management Support Scale for Kidney Transplant Recipients (SMSSKTR) and test its psychometric properties. METHODS: This is an instrument development and validation study, which has a three-stage cross-sectional design. In Stage 1, a preliminary item pool was formed using a literature review, semi-structured interviews, and the Delphi method. In Stage 2, six experts were invited to assess content validity. A convenience sample of 313 participants was used to explore the factor structure by using exploratory factor analysis. The test-retest reliability was assessed using the intra-class correlation coefficient (ICC). In Stage 3, two hundred and sixty-five participants were recruited to validate the factor structure by using confirmatory factor analysis. Convergent validity was examined using Spearman's correlation coefficient. Cronbach's alpha coefficient and corrected item-total correlation coefficient were used to test the reliability of the entire scale and its dimensions. The study was reported according to the STARD and GRRAS checklists. RESULTS: An initial 40-item scale was developed in Stage 1. In Stage 2, three factors with 22 items emerged from the exploratory factor analysis: instrumental support, psychosocial support, and relational support. The content validity index of the scale was 0.97. The intra-class correlation coefficient for the entire scale and the subscales were 0.915, 0.771, 0.896, and 0.832, respectively. In Stage 3, the confirmatory factor analysis indicated that the three-factor model had a good fit. The score of the scale was positively associated with that of the Self-Management Scale of Renal Transplant Recipients (r = 0.532). Cronbach's alpha was 0.959 for the entire scale and 0.956-0.958 for the three subscales. The corrected item-total correlation coefficient ranged from 0.62 to 0.82. CONCLUSION: The 22-item SMSSKTR has sufficient psychometric properties to assess the self-management support they have received, which has not been measured before.

Realizing Abundant Chirality Inversion of Supramolecular Nanohelices by Multiply Manipulating the Binding Sites in Molecular Blocks.

The induction of diverse chirality regulation in nature by multiple binding sites of biomolecules is ubiquitous and plays an essential role in determining the biofunction of biosystems. However, mimicking this biological phenomenon and understanding at a molecular level its mechanism with the multiple binding sites by establishing an artificial system still remains a challenge. Herein, abundant chirality inversion is achieved by precisely and multiply manipulating the co-assembled binding sites of phenylalanine derivatives (D/LPPF) with different naphthalene derivatives (NA, NC, NP, NF). The amide and hydroxy group of naphthalene derivatives prefer to bind with the carboxy group of LPPF, while carboxylic groups and fluoride atoms tend to bind with the amide moiety of LPPF. All these diverse interaction modes can precisely trigger helicity inversion of LPPF nanofibers. In addition, synergistically manipulating the carboxy and amide binding sites from a single LPPF molecule to simultaneously interact with different naphthalene derivatives leads to chirality regulation. Typically, varying the solvent may switch the interaction modes and the switched new interaction modes can be employed to further regulate the chirality of the LPPF nanofibers. This study may provide a novel approach to explore chirality diversity in artificial systems by regulating the intermolecular binding sites.

Engineered Cancer Cells as Signal Probes for Fluorescence-Assisted Digital Counting Analysis.

Fluorescence-assisted digital counting analysis allowed sensitive quantification of targets by measuring individual fluorescent labels. However, traditional fluorescent labels suffered from low brightness, small size, and sophisticated preparation procedures. Herein, engineering fluorescent dye-stained cancer cells with magnetic nanoparticles were proposed to construct single-cell probes for fluorescence-assisted digital counting analysis by quantifying the target-dependent binding or cleaving events. Various engineering strategies of cancer cells including biological recognition and chemical modification were developed for rationally designing single-cell probes. Introduction of suitable recognition elements into single-cell probes allowed digital quantification of each target-dependent event via counting the colored single-cell probes in the representative image taken using a confocal microscope. The reliability of the proposed digital counting strategy was corroborated by traditional optical microscopy- and flow cytometry-dependent counting technologies. The advantages of single-cell probes, including high brightness, big size, ease of preparation, and magnetic separation, contributed to the sensitive and selective analysis of targets of interest. As proof-to-concept assays, indirect analysis of exonuclease III (Exo III) activity, as well as direct quantitation of cancer cells, were investigated, and the potential in biological sample analysis was also assessed. This sensing strategy will open a new avenue for the development of biosensors.

The lived experiences of health care professionals regarding visiting restrictions in the emergency department during the COVID-19 pandemic: A multi-perspective qualitative study.

AIMS: To explore the lived experiences of emergency department (ED) healthcare professionals regarding visiting restrictions during the COVID-19 pandemic. DESIGN: A qualitative phenomenology study. METHODS: Semi-structured interviews were undertaken. Participants consisted of 10 physicians, 20 clinical nurses, and three managers, who were purposefully selected from two EDs in China between April and July 2021. Colaizzi's approach guided data analysis. RESULTS: Four themes arose: (i) burden moral injury, (ii) higher workload to provide and support patient- and family-centered care, (iii) dissatisfied and unsafe healthcare service for patients and families, and (iv) tailoring strategies to provide family-centered care. PATIENT OR PUBLIC CONTRIBUTION: This study explored the lived experiences of ED health care professionals regarding visiting restrictions during the COVID-19 pandemic. Noted challenges included communicating with families and ethical decision making. Strategies that support ED clinician welfare, and communication with families are warranted if visiting policy restrictions are continued or re-introduced.

Factors associated with frailty in kidney transplant recipients: A cross-sectional study.

BACKGROUND: Frailty is prevalent in kidney transplant recipients and associated with multiple health care challenges. The association between frailty and outcomes has been extensively studied in kidney transplant recipients, but the status of frailty and its associated factors are not well studied, hindering efforts to develop strategies to improve care and reduce frailty. OBJECTIVES: To identify the factors that are associated with frailty in kidney transplant recipients comprehensively. DESIGN AND PARTICIPANTS: The associated factors of frailty were explored by a cross-sectional study of 185 kidney transplant recipients. MEASUREMENTS: Data were collected using the general information questionnaire, the Charlson comorbidity index, the Pittsburgh Sleep Quality Index, the Hospital Anxiety and Depression Scale, the Connor-Davidson Resilience Scale, the Perceived Social Support Scale and the Tilburg Frailty Indicator. Data were analyzed using the multiple linear regression analysis. RESULTS: A total of 75 (40.5%) kidney transplant recipients were assessed as frail by Chinese TFI. Age (ß = 0.228), time post-transplant (ß = 0.055), sleep quality (ß = 0.224) and psychological resilience (ß = -0.038) entered the final multiple regression equation and accounted for 41.8% of the total frailty variation (R2 = 0.418, F = 21.31, p < 0.05). CONCLUSIONS: Frailty was common among kidney transplant recipients. Old age, long time after transplantation, poor sleep quality and low psychological resilience were main associated factors for frailty. Integrated care interventions are therefore needed for this vulnerable population to prevent or delay frailty.

An Overview of the Design of Metal-Organic Frameworks-Based Fluorescent Chemosensors and Biosensors.

Taking advantage of high porosity, large surface area, tunable nanostructures and ease of functionalization, metal-organic frameworks (MOFs) have been popularly applied in different fields, including adsorption and separation, heterogeneous catalysis, drug delivery, light harvesting, and chemical/biological sensing. The abundant active sites for specific recognition and adjustable optical and electrical characteristics allow for the design of various sensing platforms with MOFs as promising candidates. In this review, we systematically introduce the recent advancements of MOFs-based fluorescent chemosensors and biosensors, mainly focusing on the sensing mechanisms and analytes, including inorganic ions, small organic molecules and biomarkers (e.g., small biomolecules, nucleic acids, proteins, enzymes, and tumor cells). This review may provide valuable references for the development of novel MOFs-based sensing platforms to meet the requirements of environment monitoring and clinical diagnosis.

Biosensors for the Detection of Enzymes Based on Aggregation-Induced Emission.

Enzymes play a critical role in most complex biochemical processes. Some of them can be regarded as biomarkers for disease diagnosis. Taking advantage of aggregation-induced emission (AIE)-based biosensors, a series of fluorogens with AIE characteristics (AIEgens) have been designed and synthesized for the detection and imaging of enzymes. In this work, we summarized the advances in AIEgens-based probes and sensing platforms for the fluorescent detection of enzymes, including proteases, phosphatases, glycosidases, cholinesterases, telomerase and others. The AIEgens involve organic dyes and metal nanoclusters. This work provides valuable references for the design of novel AIE-based sensing platforms.