Multifunctional Self-Signaling nanoMIP and Its Application for a Washing-Free Assay of Human Angiotensin-Converting Enzyme 2.

Molecular imprinting techniques have attracted a lot of attention as a potential biomimetic technology, but there are still challenges in protein imprinting. Herein, multifunctional nanosized molecularly imprinted polymers (nanoMIPs) for human angiotensin-converting enzyme 2 (ACE2) were prepared by epitope imprinting of magnetic nanoparticles-anchored peptide (magNP-P) templates, which were further applied to construct a competitive displacement fluorescence assay toward ACE2. A cysteine-flanked dodecapeptide sequence was elaborately selected as an epitope for ACE2, which was immobilized onto the surface of magnetic nanoparticles and served as a magNP-P template for imprinting. During polymerization, fluorescent monomers were introduced to endow fluorescence responsiveness to the prepared self-signaling nanoMIPs. A competitive displacement fluorescence assay based on the nanoMIPs was established and operated in a washing-free manner, yielding a wide range for ACE2 (0.1-6.0 pg/mL) and a low detection limit (0.081 pg/mL). This approach offers a promising avenue in the preparation of nanoMIPs for macromolecule recognition and expands potential application of an MIP in the detection of proteins as well as peptides.

Photoelectrochemical Biosensor for MicroRNA-21 Based on High Photocurrent of TiO2/Two-Dimensional Coordination Polymer CuClx(MBA)y Photoelectrode.

Conventional photosensitive materials such as TiO2 suffer from restricted absorption in the ultraviolet region, fast recombination of photogenerated electron-hole pairs, and a lack of functional groups for biocoupling, which hinder their application in photoelectrochemical (PEC) biosensing. Herein, a new coordination polymer (CP) based on Cu(I), chloridion, and 4-mercaptobenzoic acid (MBA) has been designed and synthesized (called CuClx(MBA)y). The prepared p-type CuClx(MBA)y exhibits visible-light absorption due to its narrow optical band gap (2.59 eV), and its proper band edge position enables it to form a p-n junction with TiO2. Through layer-by-layer assembling, the photocurrent intensity of the CuClx(MBA)y/TiO2/FTO composite photoelectrode was 3.7-fold higher than that of a TiO2/FTO electrode and 35-fold higher than a CuClx(MBA)y/FTO electrode. The potential enhancement mechanism was discussed, which lies in the contributions of CuClx(MBA)y in enhancing absorption in the visible-light region and boosting the separation of electron-hole pairs of TiO2 by the p-n junction. Furthermore, CuClx(MBA)y nanosheets can realize bioconjugation directly, thanks to its abundant carboxyl groups. The CuClx(MBA)y/TiO2/FTO composite photoelectrodes were applied to develop a sensitive PEC biosensor for microRNA-21 (model target). By subtly exploiting the energy transfer between CuClx(MBA)y and Au nanoparticles (AuNPs), AuNPs served as effective quenchers. In the presence of the target, AuNP-labeled sDNA1 connected to the electrode surface, and thus, a decreased photocurrent was obtained. The proposed biosensor has a low detection limit of 0.29 fM (S/N = 3), good selectivity, and reproducibility. The proposed system was applied to monitor microRNA in cancer cells with satisfying results.

Epitope-Containing Short Peptides Capture Distinct IgG Serodynamics That Enable Differentiating Infected from Vaccinated Animals for Live-Attenuated Vaccines.

Differentiating infected from vaccinated animals (DIVA) strategies have been central enabling techniques in several successful viral disease elimination programs. However, owing to their long and uncertain development process, no DIVA-compatible vaccines are available for many important diseases. We report herein a new DIVA strategy based on hybrid protein-peptide microarrays which can theoretically work with any vaccine. Leading from our findings from peste des petits ruminants (PPR) virus, we found 4 epitope-containing short peptides (ECSPs) which have distinct IgG serodynamics: anti-ECSP IgGs only exist for 10 to 60 days postvaccination (dpv), while anti-protein IgGs remained at high levels for >1,000 dpv. These data enabled the design of a DIVA diagnostic microarray containing 4 ECSPs and 3 proteins, which, unlike competitive enzyme-linked immunosorbent assay (cELISA) and virus neutralization tests (VNTs), enables ongoing monitoring of serological differences between vaccinated individuals and individuals exposed to the pathogen. For 25 goats after 60 dpv, 13 were detected with positive anti-ECSP IgGs, indicating recent infections in vaccinated goat herds. These DIVA diagnostic microarrays will almost certainly facilitate eradication programs for (re)emerging pathogens and zoonoses.IMPORTANCE Outbreaks of infectious diseases caused by viruses, such as pseudorabies (PR), foot-and-mouth disease (FMD), and PPR viruses, led to economic losses reaching billions of dollars. Both PR and FMD were eliminated in several countries via large-scale vaccination programs using DIVA-compatible vaccines, which lack the gE protein and nonstructural proteins, respectively. However, there are still extensive challenges facing the development and deployment of DIVA-compatible vaccines because they are time-consuming and full of uncertainty. Further, the negative marker strategy used for DIVA-compatible vaccines is no longer functional for live-attenuated vaccines. To avoid these disadvantageous scenarios, a new strategy is desired. Here, we made the exciting discovery that different IgG serodynamics can be monitored when using protein-based assays versus arrays comprising ECSPs. This DIVA microarray strategy should, in theory, work for any vaccine.

A bifunctional electrochemical sensor for simultaneous determination of electroactive and non-electroactive analytes: A universal yet very effective platform serving therapeutic drug monitoring.

A novel electrochemical sensor for therapeutic drug monitoring (TDM) of antibiotic Zavicefta was developed in this work. The main components of Zavicefta are ceftazidime (CFZ) and avibactam (AVI), wherein CFZ can be oxidized directly on electrode surface, while AVI is non-electroactive. In order to realize the simultaneous detection of the two analytes on one sensor, we elaborately constructed a dual-template molecularly imprinted polymer (MIP) modified electrode with CFZ and AVI as the templates, and further developed a dual-signal strategy. During detection, due to the inhibition effect caused by rebinding of MIP to the targets, the peak current of probe ferricyanide ([Fe(CN)6]3-) showed obvious suppression. Meanwhile, a new peak appeared, which originated from the oxidation of CFZ. The proposed sensor presented a wide linear range of 50-1000 µM for CFZ and 1-1000 µM for AVI, with the respective detection limit of 35 µM and 0.5 µM (S/N = 3). Owing to the imprinting effect of MIP, the sensor displayed excellent selectivity and anti-interference ability, which was successfully applied for TDM of CFZ and AVI in human serum and a live rabbit. The results agreed well with those from HPLC. This work is expected to offer a promising avenue for simultaneous measurement of electroactive and non-electroactive substances, and extend the potential of electrochemical sensors in medical field.

Enhancing performance evaluation and microbial community analysis of the biofilter for toluene removal by adding polyethylene glycol-600 into the nutrient solution.

Polyethylene glycol-600 (PEG-600), as a carrier for slow release of organic substances, can improve the biocompatibility of packing fillers and the construction of biofilms. The gradient experiments were established to evaluate the feasibility of adding different content of PEG-600 to the biofilter for enhancing toluene removal. In particular, the evolution trend of microbial community embedded in packing fillers was measured by 16S rRNA-based gene sequencing. Results showed that the toluene removal efficiency of biofilter with 7.5% adding content of the PEG-600 was greatly improved, and the maximum elimination capacity of 152 g/(m3·h) was obtained. The introduction of PEG-600 enhanced the tolerance ability to withstand the transient impact loading and intensified the production of extracellular polymeric substances and bonding strength of biofilms. It should be noted that the abundance of Pseudomonas and Steroidobacter at genus level increased significantly. The microbial community evolved into a co-degradation system of toluene and PEG-600.

Noninvasive In Vivo Imaging and Monitoring of 3D-Printed Polycaprolactone Scaffolds Labeled with an NIR Region II Fluorescent Dye.

Significant progress has been made in fabricating porous scaffolds with ultrafine fibers for tissue regeneration. However, the lack of noninvasive tracking methods in vivo makes it impossible to track the fate of such scaffolds in situ. The development of near-infrared region II (NIR-II, 1000-1700 nm) dyes provides the possibility of performing noninvasive visualization with deep-tissue penetration and high spatial resolution in vivo. Herein, we developed a polycaprolactone (PCL) ink containing the small organic NIR-II dye SY-1030 and the fluorescently labeled macromolecular dye SY-COO-PCL and fabricated high-resolution NIR-II active scaffolds via electrohydrodynamic jet (EHDJ) printing. All printed scaffolds subcutaneously implanted in mice were clearly imaged one week after the operation. Compared with scaffolds containing SY-1030, the fluorescence intensity emitted from scaffolds containing SY-COO-PCL can be tracked for up to three weeks. Moreover, the image quality can be optimized by adjusting the dye concentration, laser power, and exposure time. The advantage of such NIR-II active scaffolds is evidenced by the lower dye concentration, longer tracking period, and better in vivo stability. We also demonstrated the biocompatibility and biodegradability of the scaffolds containing SY-COO-PCL over a 3-month period. The developed NIR-II active scaffolds have potential applications in biopolymer implant tracking, tissue reconstruction monitoring, and target-position-based drug delivery.

Molecularly imprinted polymer-decorated signal on-off ratiometric electrochemical sensor for selective and robust dopamine detection.

Dopamine (DA), as one of the central neurotransmitters, plays an important role in many physiological and pathological processes. Detection of DA is critical to diagnose and monitor some neurological diseases. In this work, a novel on-off ratiometric electrochemical sensor with molecularly imprinted polymers (MIPs) as target molecule recognizer has been developed for selective and accurate detection of DA. Nanoporous gold (NPG) was electrodeposited on bare gold electrode, which not only benefited the output signal amplification, but also provided enlarged surface for immobilization of polythionine (pThi) and MIPs. Oxidation of DA and pThi served as response signal and internal reference signal, respectively. The oxidation peak currents of DA at +0.12 V increased with increasing the concentration of DA, while the peak currents of pThi at -0.2 V decreased simultaneously. Due to the specificity from MIPs and the built-in correction from pThi, the fabricated sensor showed excellent performance in view of selectivity and reproducibility. It's worth to mention that even if the surface area and morphology of working electrode underwent huge variation deliberately, the assay deviation among these ratiometric sensors was largely reduced around 10 times. The proposed sensor demonstrated a broad dynamic range of 0.3-100 µM, as well as a low detection limit of 0.1 µM (S/N = 3). Moreover, superior anti-interfering ability toward DA detection was obtained despite the presence of interferents at high concentration in artificial cerebrospinal fluid (aCSF). Therefore, this work is expected to provide an alternative pathway for constructing ratiometric electrochemical sensor and offer reliable determination of small molecules with high selectivity and stability.

Nanorods of a new metal-biomolecule coordination polymer showing novel bidirectional electrocatalytic activity and excellent performance in electrochemical sensing.

Metal organic coordination polymers (CPs), as most attractive multifunctional materials, have been studied extensively in many fields. However, metal-biomolecule CPs and CPs' electrochemical properties and applications were studied much less. We focus on this topic aiming at electrochemical biosensors with excellent performance and high biocompatibility. A new nanoscaled metal-biomolecule CP, Mn-tyr, containing manganese and tyrosine, was synthesized hydrothermally and characterized by various techniques, including XRD, TEM, EDS, EDX mapping, elemental analysis, XPS, and IR. Electrode modified with Mn-tyr showed novel bidirectional electrocatalytic ability toward both reduction and oxidation of H2O2, which might be due to Mn. With the assistance of CNTs, the sensing performance of Mn-tyr/CNTs/GCE was improved to a much higher level, with high sensitivity of 543 mA mol(-1) L cm(-2) in linear range of 1.00×10(-6)-1.02×10(-4) mol L(-1), and detection limit of 3.8×10(-7) mol L(-1). Mn-tyr/CNTs/GCE also showed fast response, high selectivity, high steadiness and reproducibility. The excellent performance implies that the metal-biomolecule CPs are promising candidates for using in enzyme-free electrochemical biosensing.

An improved kinetics approach to describe the physical stability of amorphous solid dispersions.

The recrystallization of amorphous solid dispersions may lead to a loss in the dissolution rate, and consequently reduce bioavailability. The purpose of this work is to understand factors governing the recrystallization of amorphous drug-polymer solid dispersions, and develop a kinetics model capable of accurately predicting their physical stability. Recrystallization kinetics was measured using differential scanning calorimetry for initially amorphous efavirenz-polyvinylpyrrolidone solid dispersions stored at controlled temperature and relative humidity. The experimental measurements were fitted by a new kinetic model to estimate the recrystallization rate constant and microscopic geometry of crystal growth. The new kinetics model was used to illustrate the governing factors of amorphous solid dispersions stability. Temperature was found to affect efavirenz recrystallization in an Arrhenius manner, while recrystallization rate constant was shown to increase linearly with relative humidity. Polymer content tremendously inhibited the recrystallization process by increasing the crystallization activation energy and decreasing the equilibrium crystallinity. The new kinetic model was validated by the good agreement between model fits and experiment measurements. A small increase in polyvinylpyrrolidone resulted in substantial stability enhancements of efavirenz amorphous solid dispersion. The new established kinetics model provided more accurate predictions than the Avrami equation.