Modification of Low-Energy Surfaces Using Bicyclic Peptides Discovered by Phage Display.

Solid-binding peptides are a simple and versatile tool for the non-covalent modification of solid material surfaces, and a variety of peptides have been developed by reference to natural proteins or de novo design. Here, for the first time, we report the discovery of a bicyclic peptide targeting the heterogeneous material polypropylene by combining phage display technology and next-generation sequencing. We find that the enrichment properties of bicyclic peptides capable of binding to polypropylene are distinct from linear peptides, as reflected in amino acid abundance and a trend toward negative net charges and high hydrophobicity. The selected bicyclic peptide has a higher binding affinity for polypropylene compared with a previously reported linear peptide, enabling the hydrophilic and adhesive properties of the polypropylene to be more effectively enhanced. Our work paves the way for the exploration and utilization of conformational-restricted cyclic peptides as a new family of functionally evolvable agents for material surface modification.

Expedient Synthesis of Ubiquitin-like Protein ISG15 Tools through Chemo-Enzymatic Ligation Catalyzed by a Viral Protease Lbpro.

Ubiquitin (Ub)-like protein ISG15 (interferon-stimulated gene 15) regulates innate immunity and links with the evasion of host response by viruses such as SARS-CoV-2. Dissecting ISGylation pathways recently received increasing attention which can inform related disease interventions, but such studies necessitate the preparation and development of various ISG15 protein tools. Here, we find that the leader protease (Lbpro ) encoded by foot-and-mouth disease virus can promote ligation reactions between recombinant ISG15 and synthetic glycyl compounds, generating protein tools such as ISG15-propargylamide and ISG15-rhodamine110, which are needed for cellular proteomic studies of deISGylases, and the screening and evaluation of inhibitors against SARS-CoV-2 papain-like protease (PLpro). Furthermore, this strategy can be also used to load ISG15 onto the lysine of a synthetic peptide through an isopeptide bond, and prepare Ub and NEDD8 (ubiquitin-like protein Nedd8) protein tools.

Ultrasound Controlled Anti-Inflammatory Polarization of Platelet Decorated Microglia for Targeted Ischemic Stroke Therapy.

Stroke is a lethal cerebral disease with severe sequelae and high mortality. Microglia, the main immune cell in the cerebrum, possess therapeutic potential for strokes as its specific anti-inflammatory phenotype can reduce inflammation and promote neuron regeneration. However, the on-demand anti-inflammatory polarization of microglia at the stroke site is uncontrollable for therapeutic application. Here, we develop a platelet hybrid microglia platform which can specifically polarize to the anti-inflammatory phenotype by ultrasound irradiation for targeted cerebrum repair after stroke. The engineered microglia have strong adherence to the injured cerebral vessels with platelet membrane fusion and realize on-demand anti-inflammatory polarization with ultrasound-responsive IL-4 liposome decoration. The intravenously injected microglia platform showed anti-inflammatory polarization at the stroke site with insonation, and accelerated the M2-type polarization of endogenous microglia for long-term stroke recovery. Satisfied prognoses were achieved with reduced apoptosis, promoted neurogenesis, and functional recovery, indicating the implications of the microglia platform for stroke therapy.

Construction of H2O2-responsive asymmetric 2D nanofluidic channels with graphene and peroxidase-mimetic V2O5 nanowires.

The flexible two-dimensional (2D) nanosheet structure, high specific surface, and unique electrical properties make graphene an emerging nano-building block for molecule-responsive nanochannels. Herein, we report a novel graphene and V2O5 nanowire-based porous asymmetric membrane, which shows excellent catalytic performance and sensitive and quick response for H2O2. Poly(diallyldimethylammonium chloride)-functionalized graphene nanosheets were made into restacked lamellar film with porous structure and high anion selectivity. V2O5 nanowire, a kind of enzyme-mimetic nanomaterial, was mounted on one side of the graphene membrane through a sequential vacuum filtration method. The V2O5 nanowires on the membrane have high catalytic activities for H2O2 reduction, with the Michealis-Menten constant (KM) of 1.74 mM, better than various reported peroxidase-based nanocomposites and peroxidase mimics. This composite membrane showed quick response to H2O2 within 5 s, with good reproducibility and high operational stability. The responsive linear range was from 10 µM to 1 mM, with the detection limit of 9.5 µM. This fabrication of 2D layered nanomaterials and enzyme mimics could be extended for developing novel smart molecule-responsive devices. Graphical abstract ᅟ.

Ionic liquid assisted electrospun cellulose acetate fibers for aqueous removal of triclosan.

The cellulose acetate (CA) membrane prepared via electrospun was innovatively utilized as fiber-adsorbent for the separation of aqueous triclson (TCS). It was found that the presence of the room temperature ionic liquid (RTIL) in the precursor amplified electric force toward the CA-solution, thereby benefiting the formation of CA fibers. The as-spun CA fibers exhibit excellent adsorptive performance toward TCS, with fast adsorption kinetics, and the maximum adsorption capacity achieved to 797.7 mg g(-1), which established much better performance in contrast to conventional adsorbents. We proposed that the adsorption of TCS onto CA fibers was primarily facilitated by the hydrogen bonding between the abundant carbonyl, hydroxyl groups of CA surface, and the hydrogen atoms of phenol functional groups in TCS molecular.

DNA assembled gold nanoparticles polymeric network blocks modular highly sensitive electrochemical biosensors for protein kinase activity analysis and inhibition.

A highly sensitive electrochemical biosensor was built for the detection of kinase activity based on the DNA induced gold nanoparticles (AuNPs) polymeric network block signal amplification. In this strategy, the DNA1 conjugated AuNPs were integrated with the phosphorylated peptide by Zr(4+) and assembled into DNA-AuNPs polymeric network block by the hybridization of cDNA with each side sequences of DNA1 and joint DNA2. The kinase activity was determined by the amperometric responses of [Ru(NH3)6](3+) absorbed on the network block by electrostatic interaction. Due to its excellent electroactivity and high accommodation of the DNA-AuNPs polymeric network block for [Ru(NH3)6](3+), the current signal was significantly amplified, affording a highly sensitive electrochemical analysis of kinase activity. The as-proposed biosensor presents a low detection limit of 0.03 U mL(-1) for protein kinase A (PKA) activity, wide linear range (from 0.03 to 40 U mL(-1)), and excellent stability even in cell lysates and serum samples. This biosensor can also be applied for quantitative kinase inhibitor screening. Finally, the PKA activities from BE4S-2B, A549, and MCF-7 cell lysates were further analyzed, which provided a valuable strategy in developing a high-throughput assay of in vitro kinase activity and inhibitor screening for clinic diagnostics and therapeutics.

Sensitive nanochannel biosensor for T4 polynucleotide kinase activity and inhibition detection.

5'-Polynucleotide kinase is a crucial class of enzyme that catalyzes the phosphorylation of nucleic acids with 5'-hydroxyl termini. This process regulates many important cellular events, especially DNA repair during strand damage and interruption. The activity and inhibition of nucleotide kinase have proven to be an evident effect on cellular nucleic acid regulation and metabolism. Here, we describe a novel nanochannel biosensor for monitoring the activity and inhibition of T4 polynucleotide kinase (PNK), a famous member of the 5'-kinase family playing a major role in the cellular responses to DNA damage. On the basis of the functionalized nanochannel system and coupled λ exonuclease cleavage reaction, the nanochannel-sensing platform exhibits high sensitivity and convenience toward kinase analysis. Biotin-labeled dsDNA effectively blocks the streptavidin-modified nanochannel through forming a closely packed arrangement of DNA structure inside the channel. When dsDNA is phosphorylated by PNK and then immediately cleaved by λ exonuclease, the pore-blocking effect almost disappears. This PNK-induced microstructural distinctness can be directly and accurately monitored by the nanochannel system, which benefits from its high sensitivity to the change of the effective pore size. Furthermore, modification convenience and mechanical robustness also ensure the stability of the test platform. This as-proposed strategy exhibits excellent analytical performance in both PNK activity analysis and inhibition evaluation. The simple and sensitive nanochannel biosensor shows great potential in developing on-chip, high-throughput assays for fundamental biochemical process research, molecular-target therapies, and clinic diagnostics.

Influencing factors associated with oral health among older hospitalized patients with ischemic stroke: A cross-sectional survey.

Objective: To investigate the oral health status of older patients with ischemic stroke and analyze the influencing factors, providing valuable insights for developing effective oral health management strategies tailored for this population. Methods: A cross-sectional survey was conducted from January to June 2022, selecting 350 older patients with ischemic stroke from two tertiary hospitals in Chongqing. The Barthel Index (BI), Eating Assessment Tool (EAT-10), and Oral Health Assessment Tool (OHAT) were used to assess patients' self-care ability, swallowing function, and oral health status, respectively. A self-designed questionnaire was used to collect demographic information, disease-related information, and oral health behaviors of the patients. Binary logistic regression analysis was performed to analyze related influencing factors. Results: A total of 346 older patients with ischemic stroke were included, with 199 males and 147 females. The median total score of OHAT was 5 (total score range 0-16). Dental decay (91.7%, 278/303) and poor oral hygiene (92.2%, 319/346) were the main oral health problems in this population. Binary logistic regression analysis showed that sex, hyperlipidemia, stroke severity, stroke events, oral health behaviors, and care dependency were influencing factors for the oral health of this population (P < 0.05). Conclusion: The study revealed that healthcare professionals should strengthen the oral health assessment of older patients with ischemic stroke and implement individualized health education and management measures based on the characteristics of high-risk groups to promote their oral health.

Temperature-responsive polymer/carbon nanotube hybrids: smart conductive nanocomposite films for modulating the bioelectrocatalysis of NADH.

A temperature-sensitive polymer/carbon nanotube interface with switchable bioelectrocatalytic capability was fabricated by self-assembly of poly(N-isopropylacrylamide)-grafted multiwalled carbon nanotubes (MWNT-g-PNIPAm) onto the PNIPAm-modified substrate. Electron microscopy and electrochemical measurements revealed that these fairly thick (>6 µm) and highly porous nanocomposite films exhibited high conductivity and electrocatalytic activity. The morphological transitions in both the tethered PNIPAm chains on a substrate and those polymers wrapping around the MWNT surface resulted in the opening, closing, or tuning of its permeability, and simultaneously an electron-transfer process took place through the channels formed in the nanostructure in response to temperature change. By combining the good electron-transfer and electrochemical catalysis capabilities, the large surface area, and good biocompatibility of MWNTs with the responsive features of PNIPAm, reversible temperature-controlled bioelectrocatalysis of 1,4-dihydro-ß-nicotinamide adenine dinucleotide with improved sensitivity has been demonstrated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The mechanism behind this approach was studied by Raman spectroscopy, in situ attenuated total reflection FTIR spectroscopy, and contact angle measurements. The results also suggested that the synergetic or cooperative interactions of PNIPAm with MWNTs gave rise not only to an increase in surface wettability, but also to the enhancement of the interfacial thermoresponsive behavior. This bioelectrocatalytic "smart" system has potential applications in the design of biosensors and biofuel cells with externally controlled activity. Furthermore, this concept might be proposed for biomimetics, interfacial engineering, bioelectronic devices, and so forth.

Direct visualization of living bacterial genotypes using CRISPR/Cas12a-circular reporter nanoprobes.

Bacterial genotyping is important for understanding the complex microbiota. Although fluorescence in situ hybridization (FISH) has enabled bacterial community identification with high spatial resolution, its unavoidable cell fixation steps and signal generation by multi-probe stacking greatly limit its application in living bacterial genotyping. Here, we designed polyethyleneimine-encapsulated CRISPR/Cas12a-circular reporter nanoprobes (CasCLR) for rapid and sensitive visualization of gene information in living bacteria. We found that, nanoprobe-based sequential delivery of Cas12a/crRNA and circular reporter into bacteria allowed single genomic loci to initiate trans-cleavage activity of Cas12a, thereby cleaving CLR to generate amplified fluorescent signals for imaging of target gene. Using CasCLR, we can sensitively analyze the percentage of target bacteria in co-culture experiments and directly detect pathogenic bacteria in uncultured mouse gut microbe. In addition, CasCLR has the ability to sensitively analyze specific genotype of microbial communities in vivo. This nanobiotechnology-based bacterial gene analysis is expected to advance understanding of in vivo bacterial cytogenetic information.

Fabrication of a biocompatible and conductive platform based on a single-stranded DNA/graphene nanocomposite for direct electrochemistry and electrocatalysis.

A novel electrochemical platform was designed by combining the biocompatibility of single-stranded DNA (ss-DNA) and the excellent conductivity of graphene (GP). This nanocomposite (denoted as ss-DNA/GP) was first used as an electrode material for the immobilization and biosensing of redox enzymes. On the basis of electrostatic interactions, horseradish peroxidase (HRP) self-assembled with ss-DNA/GP on the surface of a glassy carbon (GC) electrode to form an HRP/ss-DNA/GP/GC electrode. UV/Vis and FTIR spectra were used to monitor the assembly process and indicated that the immobilized HRP on the ss-DNA/GP matrix retained its native structure well. A pair of stable and well-defined redox peaks of HRP with a formal potential of about -0.26 V (vs. Ag/AgCl) in a pH 7.0 phosphate buffer solution were obtained at the HRP/ss-DNA/GP/GC electrode; this demonstrates direct electron transfer between the immobilized HRP and the electrode. In addition, the modified electrode showed good electrocatalytic performance towards H(2)O(2) with high sensitivity, wide linear range, and good stability. Accordingly, the ss-DNA/GP nanocomposite provides a novel and efficient platform for the immobilized redox enzyme to realize direct electrochemistry and has a promising application in the fabrication of third-generation electrochemical biosensors.

Proton-driven transformable nanovaccine for cancer immunotherapy.

Cancer vaccines hold great promise for improved cancer treatment. However, endosomal trapping and low immunogenicity of tumour antigens usually limit the efficiency of vaccination strategies. Here, we present a proton-driven nanotransformer-based vaccine, comprising a polymer-peptide conjugate-based nanotransformer and loaded antigenic peptide. The nanotransformer-based vaccine induces a strong immune response without substantial systemic toxicity. In the acidic endosomal environment, the nanotransformer-based vaccine undergoes a dramatic morphological change from nanospheres (about 100 nanometres in diameter) into nanosheets (several micrometres in length or width), which mechanically disrupts the endosomal membrane and directly delivers the antigenic peptide into the cytoplasm. The re-assembled nanosheets also boost tumour immunity via activation of specific inflammation pathways. The nanotransformer-based vaccine effectively inhibits tumour growth in the B16F10-OVA and human papilloma virus-E6/E7 tumour models in mice. Moreover, combining the nanotransformer-based vaccine with anti-PD-L1 antibodies results in over 83 days of survival and in about half of the mice produces complete tumour regression in the B16F10 model. This proton-driven transformable nanovaccine offers a robust and safe strategy for cancer immunotherapy.

Direct electrochemistry and electrocatalysis based on film of horseradish peroxidase intercalated into layered titanate nano-sheets.

Intercalation of horseradish peroxidase (HRP) into layered titanate by assembling it with titanate nano-sheets (TNS) was firstly used for fabrication of enzyme electrode (HRP-TNS electrode). XRD result revealed that HRP-TNS film featured layered structure with HRP monolayer intercalated between the titanate layers. UV-vis spectra result indicated the intercalated HRP in TNS film well retained its native structure. The HRP-TNS film was uniform with porous structures which were confirmed by SEM. The immobilized HRP in the TNS film exhibited fast direct electron transfer and showed a good electrocatalytic performance to H2O2 with high sensitivity, wide linear range and low detection. The excellent electrochemical performance of the HRP-TNS electrode was attributed to biocompatibility of the titanate sheets, porous architectures of the HRP-TNS film which retained activity of HRP to large extent, avoided aggregation of HRP, provided better mass transport and allowed more HRP loading per unit area. Thus, the simple method described here provides a novel and effective platform for immobilization of enzyme in realizing direct electrochemistry and has a promising application in fabrication of the third-generation electrochemical biosensors.

A novel polyaniline/polypyrrole/graphene oxide fiber for the determination of volatile organic compounds in headspace gas of lung cell lines.

Exploration of volatile organic compounds (VOCs) generated by lung cell lines is a powerful and non-invasive tool for the detection of potential volatile biomarkers of lung cancer. In this study, a simple and sensitive solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) method was developed for the determination of VOCs in the headspace gas of lung cell lines. For the purpose of preconcentration, a novel polyaniline/polypyrrole/graphene oxide (PANI/PPy/GO) coating was prepared on the surface of stainless steel fiber via in-situ electrochemical deposition for the first time. The characteristic properties of the coating were studied and the results revealed that the coating possessed large surface area, high extraction efficiency, excellent thermal and mechanical stability as well as long lifespan. Some parameters affecting the extraction efficiency such as synthesis conditions, extraction and desorption conditions were optimized. Under the optimal conditions, the method displayed relatively wide linear range (three or four orders of magnitude) with correlation coefficients above 0.9916. Low detection limits from 1.0 to 12ngL-1 were obtained. Relative standard deviations ranged from 1.2% to 18.0% indicating good repeatability and reproducibility of the method. This method has been successfully applied to analyze VOCs in the headspace gas of lung adenocarcinoma epithelial cell line (A549) and human embryonic fibroblast cell line (MRC-5).

Hydroxyl-containing antimony oxide bromide nanorods combined with chitosan for biosensors.

A hydroxyl-containing antimony oxide bromide (AOB) nanorods was synthesized by a hydrothermal method. TEM and SEM images showed that the as-prepared AOB nanorods were very copious with diameters of about 50 nm. The AOB nanorods could be easily combined with biopolymer chitosan (Chi) to form an organic-inorganic hybrid material, and a biocompatible, crack-free and porous Chi-AOB composite film could be readily obtained. Horseradish peroxidase (HRP) was chosen as a model protein to construct a reagentless mediator-free third-generation HRP biosensor. UV-visible and FTIR spectroscopy revealed that HRP entrapped in the composite film could retain its native secondary structure. A pair of stable and well-defined redox peaks of HRP with a formal potential of about -0.24 V (vs. Ag/AgCl) in a pH 7.0 phosphate-buffered solution (PBS) were obtained at the HRP-Chi-AOB composite film modified glassy carbon (GC) electrode. With advantages of organic-inorganic hybrid materials, dramatically facilitated direct electron transfer of HRP and excellent bioelectrocatalytic activity towards H(2)O(2) were demonstrated. The apparent Michaelis-Menten constant K(M)(app) was calculated to be 7.5mum, indicating that HRP entrapped in the composite film possessed high affinity to H(2)O(2) and exhibited high enzymatic activity. The prepared biosensor displayed good sensitivity and reproducibility, wide linear range, low detection limit, fast response and excellent long-term stability. The Chi-AOB composite film could be used efficiently for the entrapment of other redox-active proteins and may find wide potential applications in biosensors, biocatalysis, biomedical devices and bioelectronics.

Functionalized polydiacetylene-glycolipid vesicles interacted with Escherichia coli under the TiO2 colloid.

The interaction of the conjugated system between functionalized polydiacetylene-glycolipid vesicles and Escherichia coli was investigated under the bactericidal effect of TiO(2) colloid. With various pre-incubation and irradiation time, controllable bacteria quantity in the presence of TiO(2) colloid was obtained in real time. UV-visible and Raman spectra were utilized to monitor and evaluate the structural transition of bacteria-polydiacetylene-glycolipid vesicles conjugated system under the different conditions, which supplied the detailed information of the transform of the polydiacetylene backbone in real time. Thus controllable conjugated bio-interaction between two bio-interfaces was obtained through the introduction of the third factor and monitored in real time. This would be great aid in fundamental understanding more complex interfaces in the biological environment and would be applicable to the biomedical and biophysical fields.

Application of impedance spectroscopy for monitoring colloid Au-enhanced antibody immobilization and antibody-antigen reactions.

We used colloidal Au to enhance the amount of antibody immobilized on a gold electrode and ultimately monitored the interaction of antigen-antibody by impedance measurement. Self-assembly of 6 nm (diameter) colloidal Au onto the self-assembled monolayers (SAMs) of 4-aminothiophenol modified gold electrode resulted in an easier attachment of antibody. The redox reactions of [Fe(CN)6](4-)/[Fe(CN)6](3-) on the gold surface were blocked due to the procedures of self-assembly of 4-aminothiophenol and antibody immobilization, which were investigated by cyclic voltammetry and impedance spectroscopy. The interaction of antigen with grafted antibody recognition layers was carried out by soaking the modified electrode into a phosphate buffer at pH 7.4 with various concentrations of antigen at 37 degrees C for 30 min. The antibody recognition layers and their interactions with various concentrations of antigen could be detected by measurements of the impedance change. The results show that this method has good correlation for detection of Hepatitis B virus surface antigen in the range of 0.5-200 microg/l and a detection limit of about 50 ng/l.

Mannose-Escherichia coli interaction in the presence of metal cations studied in vitro by colorimetric polydiacetylene/glycolipid liposomes.

Supramolecular assemblies of liposomes (vesicles) made of diacetylenic lipids and synthetic mannoside derivative glycolipid receptors were successfully used to mimic the molecular recognition occurring between mannose and Escherichia coli. This specific molecular recognition was translated into visible blue-to-red color transition (biochromism) of the polymerized liposomes, readily quantified by UV-visible spectroscopy. Some transition metal cations (Cd(2+), Ag(+), Cu(2+), Fe(3+), Zn(2+) and Ni(2+)) and alkali earth metal cations (Ca(2+), Mg(2+) and Ba(2+)) were introduced into the system to analyze their effects on specific biochromism. Results showed that the presence of Cd(2+), Ag(+), Ca(2+), Mg(2+) and Ba(2+) enhanced biochromism. A possible enhancement mechanism was proposed in the process of bacterial adhesion to host cells. However, Cu(2+), Fe(3+), Zn(2+) and Ni(2+) exhibited inhibitory effects that cooperated with diacetylene lipid with a carboxylic group and increased the rigidity of the liposomal outer leaflet, blocking changes in the side chain conformation and electrical structure of polydiacetylene polymer during biochromism.

Enhanced affinochromism of polydiacetylene monolayer in response to bacteria by incorporating CdS nano-crystallites.

By incorporating bio-specific receptors, such as p-10,12-pentacosadiyne-1-N-(3,6,9-trioxaundecylamide)-alpha-D-mannopyranoside (MPDA), into 10,12-pentacosadiyonic acid (PDA) monolayer, the MPDA/PDA monolayer underwent affinochromatic transition in response to the bacteria binding to the receptor. Here, we described a new method to study the membrane/macromolececular interaction between Escherichia coli (E. coli) and mannose and its relative affinochromism by modifying MPDA/PDA with CdS nano-crystallites (MPDA/PDA-CdS). CdS not only triggered the strong tropism of the bacteria but also reduced the rigidity of the MPDA/PDA backbone, resulting in the enhanced affinochromism. This discovery might be of significance in basic biophysical studies of membrane/macromolececular and designing novel biosensor.

High-temperature gating of solid-state nanopores with thermo-responsive macromolecular nanoactuators in ionic liquids.

Stimuli-responsive nanofluidic systems in room temperature ionic liquids (RTILs). The nanofluidic device can withstand high temperatures up to 200 °C, in which conventional water-based smart materials and nanodevices are invalid. The smart nanopores can be "irreversibly" turned off above the transition temperature of ca. 120-150 °C, actuated by the conformational change of the chemically-modified polymer brushes.