Photoelectrochemical detection of copper ions based on a covalent organic framework with tunable properties.

Copper ions (Cu2+) play an essential role in various cellular functions, including respiration, nerve conduction, tissue maturation, oxidative stress defense, and iron metabolism. Covalent organic frameworks (COFs) are a class of porous crystalline materials with directed structural designability and high stability due to the combination of different monomers through covalent bonds. In this study, we synthesized a porphyrin-tetrathiazole COF (TT-COF(Zn)) with Zn-porphyrin and tetrathiafulvalene (TTF) as monomers and used it as a photoactive material. The strong light absorption of metalloporphyrin and the electron-rich properties of supplied TTF contribute to its photoelectrochemical performance. Additionally, the sulfur (S) in the TTF can coordinate with Cu2+. Based on these properties, we constructed a highly sensitive photoelectrochemical sensor for detecting Cu2+. The sensor exhibited a linear range from 0.5 nM to 500 nM (R2 = 0.9983) and a detection limit of 0.15 nM for Cu2+. Notably, the sensor performed well when detecting Cu2+ in water samples.

Dual Functional Conjugated Acetylenic Polymers: High-Efficacy Modulation for Organic Photoelectrochemical Transistors and Structural Evolution for Bioelectronic Detection.

Conjugated acetylenic polymers (CAPs) have emerged as a unique class of metal-free semiconductors with tunable electrical and optical properties yet their full potential remains largely unexplored. Organic bioelectronics is envisioned to create more opportunities for innovative biomedical applications. Herein, we report a poly(1,4-diethynylbenzene) (pDEB)/NiO gated enhancement-mode poly(ethylene dioxythiophene)-poly(styrene sulfonate) organic photoelectrochemical transistor (OPECT) and its structural evolution toward bioelectronic detection. pDEB was synthesized via copper-mediated Glaser polycondensation of DEB monomers on the NiO/FTO substrate, and the as-synthesized pDEB/NiO/FTO can efficiently modulate the enhancement-mode device with a high current gain. Linking with a sandwich immunoassay, the labeled alkaline phosphatase can catalyze sodium thiophosphate to generate H2S, which will react with the diacetylene group in pDEB through the Michael addition reaction, resulting in an altered molecular structure and thus the transistor response. Exemplified by HIgG as the model target, the developed biosensor achieves highly sensitive detection with a linear range of 70 fg mL-1-10 ng mL-1 and a low detection limit of 28.5 fg mL-1. This work features the dual functional CAP-gated OPECT, providing not only a novel gating module but also a structurally new rationale for bioelectronic detection.

Organic Molecular Probe Enabled Ionic Current Rectification toward Subcellular Detection of Glutathione with High Selectivity, Sensitivity, and Recyclability.

Single-cell interrogation with the solid-state nanoprobes enables understanding of the linkage between cellular behavior and heterogeneity. Herein, inspired by the charge property of the organic molecular probe (OMP), a generic ionic current rectification (ICR) single-cell methodology is established, exemplified by subcellular detection of glutathione (GSH) with high selectivity, sensitivity, and recyclability. The as-developed nanosensor can transduce the subcellular OMP-GSH interaction via a sensitive ionic response, which stems from the superior specificity of OMP and its essential charge property. In addition, the nanosensor exhibits good reversibility, since the subsequent tandem reaction after the recognition can well recover the sensing surface. Given the diverse structures and tailorable charge properties of OMP, this work underpins a new and general method of OMP-based ICR single-cell analysis.

Duplex-Specific Nuclease-Enabled Target Recycling on Semiconducting Metal-Organic Framework Heterojunctions for Energy-Transfer-Based Organic Photoelectrochemical Transistor miRNA Biosensing.

Semiconductor metal-organic frameworks (MOFs) and heterojunctions have gained increasing attention in many fields, yet their full potential remains largely unexplored. Advanced optobioelectronics are envisioned to create more opportunities for innovative biomedical applications. This study reports a UiO-66-NH2 (U6N)/CdS quantum dots (QDs)-gated organic photoelectrochemical transistor (OPECT) and its application toward energy-transfer-based sensitive microRNA-166a (miRNA-166a) detection assisted by duplex-specific nuclease (DSN)-enabled target recycling. Specifically, a U6N/CdS QDs photoanode was fabricated and shown to be efficiently gating a poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT/PSS) channel, while the DSN-enabled release of Au-reporters and hybridization upon the U6N/CdS QDs photoanode could significantly inhibit the photoanode response via an energy transfer process and thus modulate the device response, permitting novel dual-amplified optobioelectronic miRNA-166a detection with a low detection limit of 1.0 fM. This work not only features the DSN-amplified miRNA detection via an OPECT route but also unveils the potential of semiconductor MOF heterojunctions for futuristic optobioelectronics.

Biological modulating organic photoelectrochemical transistor through in situ enzymatic engineering of photoactive gate for sensitive detection of serum alkaline phosphatase.

Innovative optoelectronics are expected to play more important role in clinical diagnosis. In this study, on the basis of sensitive gating effect by in situ enzymatic functionalization of semiconductors, a novel organic photoelectrochemical transistor (OPECT) detection of serum alkaline phosphatase (ALP) level was demonstrated. Specifically, the OPECT detection operates upon the ALP-catalyzed hydrolysis of sodium thiophosphate to yield hydrogen sulfide (H2S), which could in situ generate CdS on the TiO2 electrode in the presence of Cd2+ cations. Correlated to the ALP level, the CdS directly formed on and interfacing with the TiO2 could sensitively gating the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) channel, allowing unique optoelectronic detection of serum ALP level with a linear range from 0.005 to 15 U L-1 and a detection limit corresponding to 0.0012 U L-1 (S/N = 3). This study offers not only an optoelectronic method for detection of serum ALP level, but also a perspective for unique OPECT gating and application. Moreover, the general catalytic abilities of enzymes to produce functional species and their rich interactions with various gate substrates further provide great space for futuristic OPECT detection in enzyme-associated diseases.

Hybridization chain reaction for regulating surface capacitance of organic photoelectrochemical transistor toward sensitive miRNA detection.

Photon-enabled bioelectronics has long been pursued in modern electronics due to their non-contact, remote-control, and even self-powered function interfacing the biological world with semiconductor devices. The debuting organic photoelectrochemical transistor (OPECT) relies on the photovoltage generated by the semiconductors to modulate the channel conductance, which enables light-fueled operation at zero gate bias. Inspired by the insulating nature of macrobiomolecules and surface capacitance mechanism, herein we demonstrate the biological regulation of the surface capacitance towards new OPECT biodetection, which was exemplified by a CdS quantum dots/TiO2 nanotubes photoanode accommodating hybridization chain reaction (HCR) amplification with the target of biomarker miRNA-17. Formation of the non-conducting DNA layer from the miRNA-17-oriented HCR could decrease the surface capacitance and increase the corresponding fractional potential drop, shifting the transfer curve horizontally to higher gate voltage and thus producing different drain currents. The OPECT biosensor exhibited a linear relationship with the miRNA-17 concentration on the logarithmic axis in the range from 1 pm. to 10 µm with a detection limit of 1 pm. This work not only represented a generic methodology of miRNA detection, but also provided a universal mechanism for the operation of advanced OPECT bioanalytics.

Bio-polyols based waterborne polyurethane coatings reinforced with chitosan-modified ZnO nanoparticles.

The development of environmentally friendly waterborne polyurethane (WPU) coatings from bio-based polyols has received much attention due to increasing environmental concern and the depletion of petroleum resources. In this study, the WPU coatings derived from castor oil and soy polyol were modified by chain extender [bis(2-hydroxyethyl)amino]-methyl-phosphonic acid dimethyl ester. The effect of chitosan-modified ZnO (CS-ZnO) nanoparticles content on the properties of WPU/CS-ZnO coatings and their films were systematically investigated. The results indicated that WPU/CS-ZnO coatings displayed excellent storage stability and the particle sizes firstly decreased and then increased with CS-ZnO loading. CS-ZnO could improve tensile strength and Young's modulus but reduce the optical transparency of WPU/CS-ZnO films. CS-ZnO has a prominent reinforcement effect on the WPU/CS-ZnO matrix. With the addition of 2 wt% CS-ZnO, the tensile strength and Young's modulus of the WPU/CS-ZnO2 film reached 13.4 and 112.1 MPa, 1.68 and 2.6 times over neat WPU film, respectively. TGA results showed that the thermal stability of WPU/CS-ZnO films improved with increased CS-ZnO content. Furthermore, the WPU/CS-ZnO films' wettability decreased with the introduction of CS-ZnO. This work provides a simple and efficient strategy for preparing environmentally friendly bio-based WPU coatings, which are promising for application in the surface coating industry.

Research Progress in the Multilayer Hydrogels.

Hydrogels have been widely used in many fields including biomedicine and water treatment. Significant achievements have been made in these fields due to the extraordinary properties of hydrogels, such as facile processability and tissue similarity. However, based on the in-depth study of the microstructures of hydrogels, as a result of the enhancement of biomedical requirements in drug delivery, cell encapsulation, cartilage regeneration, and other aspects, it is challenge for conventional homogeneous hydrogels to simultaneously meet different needs. Fortunately, heterogeneous multilayer hydrogels have emerged and become an important branch of hydrogels research. In this review, their main preparation processes and mechanisms as well as their composites from different resources and methods, are introduced. Moreover, the more recent achievements and potential applications are also highlighted, and their future development prospects are clarified and briefly discussed.

Structure and properties of cellulose/HAP nanocomposite hydrogels.

The exploiting of abundant natural polymers as potential absorbents for heavy metal ions is attracting. Cellulose is the most abundant natural polymer and exhibits amazing properties such as high chemical stability, hydrophilicity and biodegradability. However, some properties of pure cellulose-based materials including adsorbability are usually not enough, so it is important to improve their properties to broaden their applications. In the present work, hydroxyapitite (HAP) nanoparticles were prepared and introduced to improve the cellulose hydrogel (CG) properties. The structure and properties of the resultant cellulose/HAP nanocomposite hydrogels (CHG) were characterized and studied systematically. The results indicated that HAP nanoparticles was fixed and distributed evenly in CG. The maximum decomposition temperature increased gradually from 334.6 °C for CG to 346.7 °C for CHG, and the compressive strength increased gradually from 100 kPa for CG to 570 kPa for CHG with the increase of HAP content, respectively. Moreover, the adsorption capacity (qe) value of CHG towards Cu2+ could reach more than 300% higher than that of CG. As a potential absorbent, CHG exhibited relatively good recyclability of more than 78% after 10 cycles. Therefore, the introduction of HAP improved the properties of CG greatly, showing wide potential applications.

Phosphate removal using surface enriched hematite and tetra-n-butylammonium bromide incorporated polyacrylonitrile composite nanofibers.

The nanosized iron oxides-based adsorbent has been widely used to alleviate water eutrophication. However, it is challenging to industrialize the application of nanosized iron oxides-based adsorbent due to their poor stability, difficult separation and recovery. Herein, hematite and tetra-n-butylammonium bromide incorporated polyacrylonitrile (PAN/Fe2O3/TBAB) composite nanofibers with a controlled diameter (i.e., 66 to 305 nm) and composition were systematically synthesized as an adsorbent for phosphate removal from water using surfactant-mediated electrospinning. During the electrospinning process, polar TBAB surfactant enhanced the migration of Fe2O3 nanoparticles toward the surface of nanofibers resulting in Fe2O3 nanoparticles/TBAB surface enriched nanofibers. The synthesized nanofiber membranes were used for phosphate removal, and their adsorption kinetics, adsorption mechanism, and reusability were investigated. Data showed that adsorption kinetic followed the pseudo-second-order model whereas the adsorption mechanism follows the Langmuir model. The phosphate removal was mainly derived from the chemisorption of surface-enriched α-Fe2O3 nanoparticles at acidic and circumneutral pH values, with a small contribution from anion exchange at TBAB sites. The maximum phosphate removal capacity was approx. 8.76 mg/g (i.e., 23.1 mg/g, P/active materials) at pH 3. Additionally, the synthesized nanofiber membrane also shows excellent reusability.

Nurses' Perceptions of Factors Influencing Elder Self-neglect: A Qualitative Study.

PURPOSE: Elder self-neglect is a global public health issue and should be taken seriously at large. Nurses, usually working directly with elderly patients, have a better understanding of what factors may cause elder self-neglect. In this qualitative study, we explored the influencing factors of elder self-neglect from the perception of nurses in the context of Chinese culture. METHODS: Face-to-face, in-depth interviews were conducted from November 2018 to December 2018. Purposive sampling was used. Twenty one participants recruited from eight geriatric wards of a general hospital located in Wuhan were interviewed. A content analysis of qualitative nature was performed to analyze the data. RESULTS: Our conceptual model illustrated the findings based on the three themes of the conflict between personal recognition and social judgment, the choice between current needs and individual beliefs, as well as the compromise between insufficient abilities and limited resources. CONCLUSION: Nurses together with family members and social workers can help older adults improve their awareness of self-neglect to bridge the gap with social judgment, learn to focus on their own needs, as well as seek as much support as possible. Nurses should also respect the autonomy and self-determination of elder self-neglecters because self-neglect is related to older adults' values. Furthermore, larger studies are needed to quantitatively test and refine the model.

Biocompatible and biodegradable chitosan/sodium polyacrylate polyelectrolyte complex hydrogels with smart responsiveness.

Bulk homogeneous polyelectrolyte complex hydrogels (PCH) are difficult to prepare due to the flocculation effect between polyelectrolytes with opposite charges. Herein, novel chitosan/sodium polyacrylate (PAAS) polyelectrolyte complex hydrogels (CPG) were fabricated successfully by cross-linking chitosan and PAAS with epichlorohydrin (ECH) through inhibiting protonation effect of chitosan in alkali/urea aqueous solution. The swelling behaviors of CPG were studied systematically in different solutions. The equilibrium swelling ratio of chitosan hydrogel in water increased dramatically from 46.3 to 404.8 g/g by the introduction of PAAS. CPG exhibited different swelling ratios towards different pH solutions, physiological solutions and salt solutions with different concentrations, showing obvious smart responsive properties. Moreover, CPG hydrogels exhibited relatively high compressive strength, good biocompatibility and in vitro biodegradability. Therefore, this work provided a novel PCH and shed light on the fabrication of other PCH, showing potential applications in the fields of agriculture, foods, tissue engineering and drug delivery.

Tyrosinase-encapsulated liposomes: Toward enzyme-induced in situ sensitization of semiconductor for sensitive photoelectrochemical immunoassay.

Liposomal photoelectrochemical (PEC) bioanalysis holds enormous potential for future sensitive PEC bioanalysis. With tyrosinase (Tyr) and TiO2 as representative enzyme and electrode, respectively, this communication reports the elegant use of Tyr-loaded liposomes (TLL) toward in situ sensitization of the electrode and thereby the realization of ultrasensitive PEC immunoassay. Specifically, Tyr-encapsulated and detection antibody-functionalized liposomes were first prepared and used as the signal probe. The subsequent sandwich immunobinding could confine the functional liposomes, which were then lysed with surfactant to release the encapsulated Tyr. The free Tyr could then initiate the transformation of tyrosine to dopa, the latter could bind with the undercoordinated Ti sites, forming the stable dopa-Ti charge transfer complex and thus generating enhanced anodic photocurrent under visible light for signaling. Since different semiconductors and enzymes may be adapted into this format, this work is expected to stimulate more interest in the enzyme-induced activation of semiconductors for advanced liposomal PEC bioanalysis.

Gold Nanoparticle-Induced Photocurrent Quenching and Recovery of Polymer Dots: Toward Signal-On Energy-Transfer-Based Photocathodic Bioanalysis of Telomerase Activity in Cell Extracts.

Energy transfer (ET) in photoelectrochemical (PEC) bioanalysis is usually generated between noble metal nanoparticles (NPs) and traditional inorganic quantum dots (QDs). Using the innovative polymer dot (Pdot)-involved ET, this work reports the first signal-on and cathodic PEC bioanalysis toward telomerase (TE) activity in cell extracts. Specifically, the sequential binding of capture DNA (cDNA), telomerase primer sequence (TS), and Au NP-labeled probe DNA (Au NP-pDNA) on the electrode would place the Au NPs in close proximity of the Pdots, leading to obvious quenching of the cathodic photocurrent. The subsequent extension of the TS by TE in the presence of deoxyribonucleoside triphosphates (dNTPs) would then release the Ag NP-pDNA from the electrode, leading to the recovery of the photocurrent. On the basis of the Au NP-induced photocurrent quenching and the recovery of Pdots, a sensitive biosensor could thus be developed by tracking the photocurrents to probe the TE activity. This strategy allows for signal-on and cathodic PEC bioanalysis of TE, which can be easily extended for numerous other targets of interest. We believe this work could offer a new perspective for the rational implementation of Pdot-involved ET for advanced PEC bioanalysis.

The therapeutic effect of pelvic floor muscle exercise on urinary incontinence after radical prostatectomy: a meta-analysis.

Pelvic floor muscle exercise (PFME) is the most common conservative management for urinary incontinence (UI) after radical prostatectomy (RP). However, whether the PFME guided by a therapist (G-PFME) can contribute to the recovery of urinary continence for patients after RP is still controversial. We performed this meta-analysis to investigate the effectiveness of G-PFME on UI after RP and to explore whether the additional preoperative G-PFME is superior to postoperative G-PFME alone. Literature search was conducted on Cochrane Library, Embase, Web of Science, and PubMed, to obtain all relevant randomized controlled trials published before March 1, 2018. Outcome data were pooled and analyzed with Review Manager 5.3 to compare the continence rates of G-PFME with control and to compare additional preoperative G-PFME with postoperative G-PFME. Twenty-two articles with 2647 patients were included. The continence rates of G-PFME were all superior to control at different follow-up time points, with the odds ratio (OR) (95% confidence interval [CI]) of 2.79 (1.53-5.07), 2.80 (1.87-4.19), 2.93 (1.19-7.22), 4.11 (2.24-7.55), and 2.41 (1.33-4.36) at 1 month, 3 months, 4 months, 6 months, and 12 months after surgery, respectively. However, there was no difference between additional preoperative G-PFME and postoperative G-PFME, with the OR (95% CI) of 1.70 (0.56-5.11) and 1.35 (0.41-4.40) at 1 month and 3 months after RP, respectively. G-PFME could improve the recovery of urinary continence at both early and long-term stages. Starting the PFME preoperatively might not produce extra benefits for patients at early stage, compared with postoperative PFME.

Surgical Versus Non-Surgical Methods for Acute Achilles Tendon Rupture: A Meta-Analysis of Randomized Controlled Trials.

We performed a meta-analysis to (1) compare surgical and non-surgical treatment methods for repair of acute rupture of the Achilles tendon, in terms of the re-rupture rate, incidence of complications other than re-rupture, functional outcomes, and proportion of patients returning to previous levels of sporting activities, and (2) explore the difference in the re-rupture rate if proven early functional rehabilitation protocols were followed. PubMed, EMBASE, Medline, and Cochrane Central Register of Controlled Trials databases were searched to identify randomized clinical trials. The quality of included studies was assessed by the Cochrane risk-of-bias tool. The random-effects model or subgroup analysis would be chosen to perform the meta-analysis if the data were heterogeneous; otherwise, the fixed-effect model would be selected. Ten randomized clinical trials with a total of 934 randomized patients were included. Patients in the non-surgical group underwent higher re-ruptures than patients in the surgical group (p = .0002), but the re-rupture rates were equivalent in the non-surgical group and the surgical group (p = .08) if an early range of motion exercises protocol was performed. Lower incidence of complications excluding re-rupture was found in non-surgical patients (p = .006). However, the surgical group had better results in functional outcomes when evaluated by 2 different jump tests (drop counter-movement jump [p = .002], Hopping [p = .004]) and 1 muscular endurance test (Heel-rise work [p = .01]). The 2 groups had no significant difference in the proportion of patients returning to previous levels of sporting activities (p = 0.87). The risk of re-rupture after surgical or non-surgical treatment was equivalent if a functional rehabilitation protocol with early range of motion was performed, but the risk of other complications happening after surgical treatment was higher than in non-surgical treatment.

Reinforcement of Castor Oil-Based Polyurethane with Surface Modification of Attapulgite.

Polyurethane/attapulgite (PU/ATT) nanocomposites derived from castor oil were prepared by incorporation of 8 wt % ATT, acid-treated ATT, and KH560-treated ATT. The effects of three ATTs (ATT, acid-ATT, and KH560-ATT) on the comprehensive properties of PU/ATT nanocomposites were systematically investigated. The results showed that the incorporation of 8 wt % of three ATTs could produce an obvious reinforcement on the castor oil-based PU and that the silane modification treatment, rather than the acid treatment, has the more effective reinforcement effect. SEM images revealed the uniform dispersion of ATT in the PU matrix. DMA confirmed that the storage modulus and glass transition temperature (Tg) of PU/ATT nanocomposites were significantly increased after blending with different ATTs. For PU/KH560-ATT8 nanocomposites, the thermal stability of the PU was obviously enhanced by the addition of KH560-ATT. In particular, 8 wt % KH560-ATT loaded castor oil-based PU nanocomposites exhibit an obvious improvement in tensile strength (255%), Young's modulus (200%), Tg (5.1 °C), the storage modulus at 25 °C (104%), and the initial decomposition temperature (7.7 °C). The prepared bio-based PU materials could be a potential candidate to replace petroleum-based PU products in practical applications.

Impact Resistance Enhancement by Adding Core-Shell Particle to Epoxy Resin Modified with Hyperbranched Polymer.

A core-shell particle was fabricated by grafting amino-terminated hyperbranched polymer to the surface of silica nanoparticles. The influences of core-shell particle contents on the tensile and impact strength of the epoxy thermosets modified with amino-terminated hyperbranched polymer were discussed in detail. For comparison, core-shell particle was added into the epoxy/polyamide system for toughness improvement. Results from tensile and impact tests are provided. The introduction of core-shell particle into the epoxy/polyamide systems just slightly enhanced the tensile and impact strength. The incorporation of 3 wt % core-shell particle could substantially improve the tensile and impact strength of epoxy/amino-terminated hyperbranched polymer thermosets. Field emission-scanning electron microscope images of the impact fracture surfaces showed that the excellent impact resistance of epoxy/amino-terminated hyperbranched polymer/core-shell particle thermosets may be attributed to the synergistic effect of shearing deformation and crack pinning/propagation, which is induced by the good compatibility between epoxy matrix and core-shell particle in the presence of amino-terminated hyperbranched polymer.

Novel Photoresponsive Linear, Graft, and Comb-Like Copolymers with Azobenzene Chromophores in the Main-Chain and/or Side-Chain: Facile One-Pot Synthesis and Photoresponse Properties.

Novel photoresponsive linear, graft, and comb-like copolymers with azobenzene chromophores in the main-chain and/or side-chain are prepared via a sequential ring-opening metathesis polymerization (ROMP) and head-to-tail acyclic diene metathesis (ADMET) polymerization in a one-pot procedure using Grubbs ruthenium-based catalysts. The diluted solutions of these as-prepared copolymers containing azobenzene chromophores exhibit photochemical trans-cis isomerization under the irradiation of UV light, followed by their cis-trans back-isomerization in visible light. The rates of photoisomerization are found to be slower than those of back-isomerization, and the rate for the comb-like copolymer is found to be from 3 to 7 times slower than that obtained for the linear or graft copolymer. This is ascribed to the differences in structure of the copolymers and the specific location of azobenzene chromophores in the copolymer, which favor a side-chain graft structure.