Highly crosslinking core-shell magnetic nanocomposites based catalyst and heat free polymerization for isolation of glycoprotein.

New approaches for the engineering of well-defined, pore modality, and multi-chemical functionality nanocomposites are crucial to generate the next generation of functional materials with recoverable and easy preparation properties. Here, a catalyst and heat free polymerization reaction is exploited and fabricated zwitterionic system around magnetic nanoparticles. N-aminoethyl piperazine propane sulfonate (AEPPS) and dopamine (DA) are introduced as the zwitterionic system, which provided abundant zwitterionic groups (NH2, SO3-, N+) and strong adhesion and various oxidation state properties. And that, the zwitterionic engineering will assemble between AEPPS and DA whereby Schiff base formation or Michael type addition. Whereafter, a series of sophisticated array of microscopic, spectroscopic, and structure techniques verify the formation of highly crosslinking internal zwitterionic architectures, well-defined core-shell structure, and better porosity. The zwitterionic structure-function relationships and striking porous structure are explored in a multi-interaction adsorption assay. The adsorption capacity of the magnetic nanocomposites was 1065.8 mg/g. And that, the system exhibited with hydrophilic-hydrophobic activity towards glycoprotein and better performance to bioactive protein (Ig-G) isolation form human whole blood sample. The synergistic enhancement interaction in hydrophilic target enrichment, easy preparation, and soft substrate properties of the AEPPS-DA zwitterionic materials make them intriguing candidates for sustainable biomedical loading and chromatographic separation.

Ratiometric fluorescence probe of MIPs@CdTe QDs for trace malachite green detection in fish.

A facile and practical ratiometric fluorescence probe based on two CdTe quantum dots (QDs) coated with molecularly imprinted polymers (MIPs) was prepared for the detection of trace malachite green (MG) in fish. Two CdTe QDs coated with MIPs were fabricated by a one-pot method using MG, (3-aminopropyl) triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) as template, functional monomer, and cross-linker, respectively. CdTe QDs with λem 530 nm (gQDs) and 630 nm (rQDs) were used as the referential fluorophore and target sensitive fluorophore, respectively. The fluorescence intensity of gQDs remained unchanged in the presence of MG, while the fluorescence of rQDs could be quantitatively quenched by MG based on the strategy of fluorescence resonance energy transfer. The ratiometric fluorescence probe (MIPs@gQDs&rQDs) was characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The linear range of MG detection was 0.1-32 µmol L-1 with a detection limit of 8.8 µg kg-1. The constructed probe has been successfully applied to the detection of MG in fish with the recoveries of 92.3-109.1%, which were validated by the method of HPLC. The result indicated that the probe possessed rapid response, wide linear range, high sensitivity, and relatively high selectivity, and was low-cost and easy in operation in the detection of MG in fish samples.

Anti-galvanic reaction induced interfacial engineering to reconstruct ternary colloid satellite platform for exceptionally high-performance redox-responsive sensor.

The anti-galvanic reaction (AGR), which is a classic galvanic reaction (GR) with an opposite effect, is a unique phenomenon associated with the quantum size effect. This reaction involves the interaction between metal ions and nanoclusters, offering opportunities to create well-defined nanomaterials and diverse reductive behavior. In hence, in our work, we utilize the AGR to generate gold (Au), silver (Ag), and copper (Cu) satellite nanoclusters which have superior electromagnetic properties for Surface-enhanced Raman spectroscopy (SERS) sensor. As the AGR process, weak oxidant Cu2+ is selected to etched matrix Au@Ag NPs, reduced to Cu(0) or Cu(1) and generated the ultrasmall metal nanoparticles (Ag). To facilitate the AGR, we introduce the nucleophilic thiol 4-mercaptopyridine (4-Mpy) to bridge the metal ions or ultrasmall metal nanoparticles to reconstruct the satellite nanoclusters. These experimental displays that the AGR based biosensors has highly sensitivity for reductive molecule glucose. The liner ranges from 1 mmol/L to 1 nmol/L and alongs with a correlation coefficient and detection limit (LOD) of 0.999 and 0.14 nmol/L. Moreover, the AGR based biosensors exhibits remarkable stability and high repeatability with RSD 1.3 %. The food samples are tested to further investigate the accuracy and reliability of the method, which provides a novel and effective SERS method for the reduction molecules detection.

Design of competition nanoreactor with shell-isolated colloidal plasmonic nanomaterials for quantitative sensor platform.

Shell-isolated colloid plasmonic nanomaterials-based nanoreactor is a well-established platform widely applied in catalyst or Surface Enhanced Raman Scattering (SERS) sensors. The potentials versatility of nanoreactor platform is mainly implemented by the well-defined and tailorable structure of colloid plasmonic nanomaterials. Currently, a competitive conjugative-mediated nanoreactor is introduced to determine glucose with SERS. Glucose-conjugating nanoreactor, as convertors of the sensors, are constructed by coordinated deposition colloidal gold nanoparticles with sodium nitroprusside framework (Au@SNF) and covalently bonded 4-mercaptopyridine (4-Mpy) with self-assembly strategy. The nanoreactor contained the signal-amplifier Au@SNF NPs, conjugative-mediated signal receiver 4-Mpy, and signal internal standard molecular CN-. In addition to well-defined morphology and functionality, conjugative-mediated and internal standards method are also employed to benefit the nanoreactor. The two-parameter strategy significantly improves the signal indication and correction. Using this proposed platform, the competitive-mediated nanoreactor provides a quantitative SERS detection of glucose, and extends the applicability of SERS in more complicated and reproducibility analysis. Meanwhile, the nanoreactor based sensors also exhibited better properties to detect glucose in various food samples and bio-samples which provided strongly appliance for glucose sensors.

Construction of Metal Hydrate-Based Amorphous Magnetic Nanosheets for Enhanced Protein Enrichment and Immobilization.

Inspired by the hierarchical fabrication technique, many self-assembly procedures have improved the construction of nanomaterials with unique physicochemical characteristics and multiple functions. The generation of multiple complexes is always accompanied by hierarchical structures and intriguing properties that are distinct from their individual segments. An interesting composite is amorphous magnetic Zn-Zr phosphate hydrated nanosheets (Zn-Zr APHNs), generated using templated synthesis and nanoparticle codeposition. The special porous structure of this construct, together with the abundance of metal ions and hydrate present, endows it with many interaction sites for proteins, provides high loading efficiency, and enhances bioactivity. Then, a series of proteins, including enzymes, was immobilized by the Zn-Zr APHNs by multiple interactions, high ionization, and larger surface of the nanosheets. In this study, novel methods for the enrichment of bioactive proteins while retaining the activity of protein payloads are presented. As a verification method, it is indicated that the Zn-Zr APHNs can deliver enzyme proteins (i.e., Cyt-c) to increase the catalytic activity with their biological function and structural integrity, resulting in a highly increased activity to free proteins.

A dichromatic label-free aptasensor for sulfadimethoxine detection in fish and water based on AuNPs color and fluorescent dyeing of double-stranded DNA with SYBR Green I.

A dichromatic label-free aptasensor was described for sulfadimethoxine (SDM) detection. Compared with the binding of SDM-aptamer to SDM, the higher affinity of aptamer to cDNA may result in the hybridization of dsDNA. In the presence of SDM, the aptamer specifically binds to SDM, leading to a blue color of AuNPs in deposit and fluorescence at 530 nm in supernatant after adding cDNA and SGI. With no target of SDM, AuNPs protected with the aptamer re-disperse in PBS with a red color, and no fluorescence occurs in supernatant. Based on the principle, SDM can be quantitatively detected through both fluorescent emission and AuNPs color changes with recoveries ranging from 99.2% to 102.0% for fish and from 99.5% to 100.5% for water samples. An analytical linear range of 2-300 ng mL-1 was achieved with the detection limits of 3.41 ng mL-1 for water and 4.41 ng g-1 for fish samples (3σ, n = 9).

A taurine-functionalized 3D graphene-based foam for electrochemical determination of hydrogen peroxide.

We present a synthesis approach of taurine-functionalized graphene foam (a-NSGF) using hydrothermal reduction, freeze-drying and high temperature annealing. The higher temperature in annealing allowed the N/S atoms of taurine enter into the graphene lattice, which improves its electrocatalytic activity greatly. The a-NSGF consisting of taurine that modified into 3D layers of graphene and endow is of the rapid sensitive to hydrogen peroxide (H2O2). The electrode using a-NSGF modification reveals highly sensitive and stable towards the concentration change of H2O2 due to the stable 3D structure and good electrical conductivity of a-NSGF. A linear correlation between H2O2 concentration and the electrochemical signal is found to be in a range from 1.5 to 300 µM and the correlation coefficient is R2 = 0.999. The modified electrode has been applied in the determination of H2O2 in rain samples and the results have been compared with the China National Standard Method. The recoveries range from 94.6% to 106.7%. These results show that the proposed sensor is promising for the development of novel electrochemical sensing for H2O2 determination.

Label-Free Fluorescence-Based Aptasensor for the Detection of Sulfadimethoxine in Water and Fish.

Fluorescence-based aptasensors possess high sensitivity but are complicated and usually require multistep labeling and modification in method design, which severely limit the practical applications. Here, a label-free fluorescence-based aptasensor, consisting of aptamer, gold nanoparticles (AuNPs), and cadmium telluride (CdTe) quantum dots (QDs), was developed for the detection of sulfadimethoxine (SDM) in water and fish based on the specific recognition of SDM-aptamer and the inner filter effect of QDs and AuNPs. In the absence of a target, AuNPs dispersed in salt solution because of the aptamer protection, which could effectively quench the fluorescence emission of QDs, while in the presence of SDM, AuNPs aggregated due to the specific recognition of SDM-aptamer to SDM, which resulted in fluorescence recovery. A linear response of SDM concentrations in the range of 10-250 ng mL-1 ( R2 = 0.99) was obtained, and the detection limit was 1.54 ng mL-1 (3σ, n = 9), far below the maximum residue limit (100 ng mL-1) of SDM in edible animal tissues regulated by China and the European Commission. The fluorescence-based aptasensor was applied to the detection of SDM in aquaculture water and fish samples with high accuracy, excellent precision, and ideal selectivity. The results indicated that the developed aptasensor was simple in design, easy to operate, and could be used to detect rapidly and accurately SDM in water and fish samples.

High sensitive and label-free colorimetric DNA detection based on nicking endonuclease-assisted activation of DNAzymes.

Horseradish peroxidase mimicking DNAzyme (HRP-DNAzyme) attracts growing interest as an amplifying label for biorecognition and biosensing events, especially for DNA detection. However, in the traditional designs, one target molecule can only generate one HRP-DNAzyme, which limits the signal enhancement and thus its sensitivity. In this article, we propose an amplified and label-free colorimetric DNA detection strategy based on nicking endonuclease (NEase)-assisted activation of HRP-DNAzymes (NEAA-DNAzymes). This new strategy relies on the hairpin-DNAzyme probe and NEase-assisted target recycling. In the hairpin-DNAzyme probe, the HRP-DNAzyme sequence is protected in a "caged" inactive structure, whereas the loop region includes the target complementary sequence. Upon hybridization with target, the beacon is opened, resulting in the activation of the HRP-DNAzyme. Meanwhile, upon formation of the duplex, the NEase recognizes a specific nucleotide sequence and cleaves the hairpin-DNAzyme probe into two fragments. After nicking, the fragments of the hairpin-DNAzyme probe spontaneously dissociate from the target DNA. Amplification is accomplished by another hairpin-DNAzyme probe hybridizing to the released intact target to continue the strand-scission cycle, which results in activation of numerous DNAzymes. The activated HRP-DNAzymes generate colorimetric or chemiluminescence readout signals, thus providing the amplified detection of DNA. The detection limit of the colorimetric method is 10 pmol/L, which are three orders of magnitude lower than that without NEase. In addition, the detection limit of the chemiluminescence method is 0.2 pmol/L. Meanwhile, this strategy also exhibits high discrimination ability even against single-base mismatch.

A graphene oxide platform for energy transfer-based detection of protease activity.

In this article, we report the first graphene oxide (GO)-based platform to detect protease activity in a homogeneous real-time format. In designing such GO-based biosensing platform, we put a protease substrate peptide as the linker between the energy transfer donor (QDs) and the energy transfer acceptor (GO) to fabricate the GO-peptide-QDs nanoprobes. In the nanoprobes, the photoluminescence (PL) of donor QDs was strongly quenched due to the presence of GO in close proximity. The protease activity caused modulation in the efficiency of the energy transfer between the acceptor and donor, thus enabling the protease assay. The proposed GO-based platform is easy to assemble and has little background interference, yet still give superior sensitivity and rapid response. Furthermore, this GO-QDs architecture can serve as a universal platform by simply changing the types of peptide sequences for the different proteases. In this work, GO-based platform has been successfully applied in the sensitive detection of matrix metalloproteinase (MMP) and thrombin activity. Meanwhile, we also utilized this platform to monitor the protease inhibitor. The proposed GO-based platform is anticipated to find applications in the diagnosis of protease-related diseases and screening of potential drugs with high sensitivity in a high-throughput way.

A quartz crystal microbalance sensor based on mussel-inspired molecularly imprinted polymer.

In this work, we describe a simple, inexpensive and fast method for the generation of molecularly imprinted polymer (MIP) film on quartz crystal microbalance (QCM) crystals using mussel-inspired polymer. Commonly known as a neurotransmitter, dopamine is also a small-molecule mimic of the adhesive proteins of mussels. Polymerization of dopamine in the presence of template molecule (1,3,5-pentanetricarboxylic acid, an analogue of domoic acid, in this case) could produce an adherent molecularly imprinted polydopamine film coating on QCM crystals. Advantages, such as high hydrophilicity, high biocompatibility and controllable thickness, make this molecularly imprinted polydopamine film an attractive recognition element for sensors. Selective rebinding of domoic acid on mussel-inspired molecularly imprinted polymer (m-MIP) coated crystal was observed as a frequency shift quantified by piezoelectric microgravimetry with the QCM system. The decreasing frequency shows a good linear relationship with the concentration of domoic acid. The quantitation limit of domoic acid was 5 ppb with the linear range of 0-100 ppb. The QCM sensor has high selectivity and was able to distinguish domoic acid from its analogous p-phthalic acid and o-phthalic acid owing to the molecular imprinting effect. In addition, the practical analytical performance of the sensor was examined by evaluating the detection of domoic acid in mussel extracts with satisfactory results. It is envisaged that m-MIP could be suitable as recognition element for sensors and the proposed m-MIP QCM sensor could be employed to detect analyte of interest in complex matrices.

[Effects of warming-reinforcing acupuncture combined with rehabilitation training on the early motor function of hemiparalysis patients caused by ischemic brain stroke: a randomized and controlled study].

OBJECTIVE: To verify the improvement function of warming-reinforcing acupuncture combined with rehabilitation training on the early motor function of hemiparalysis patients caused by ischemic brain stroke. METHODS: Eighty cases were randomly divided into a warming-reinforcing acupuncture combined with rehabilitation training group (group A) and a rehabilitation training group (group B), 40 cases in each group. Both groups were treated with internal routine treatment. The Motor Relearning Program rehabilitation was used in group B, while warming-reinforcing acupuncture combined with Motor Relearning Program rehabilitation were used in group A. Jianyu (LI 15), Quchi (LI 11), Hegu (LI 4), Yanglingquan (GB 34), Yinlingquan (SP 9), Zusanli (ST 36), Sanyinjiao (SP 6) were selected, and warming-reinforcing method was used in these points, they were treated for 3 weeks. The neurological functional deficits scores of hemiparalysis patients, Fugl-Meyer Score, Motor Function Assessment Score (MAS), Barthel Index and Mini-mental State Examination (MMSE) were used to evaluate the condition of hemiparalysis patients before and after treatment. RESULTS: The effective rate of group A (87.5%, 35/40) superior to that of group B (67.5%, 27/40) (P < 0.05). The neurological functional deficit scores, Fugl-Meyer score, MAS and Barthel Index of both groups were improved after treatment (P < 0.01, P < 0.05), and the improved degree of group A was better than that of group B (P < 0.01, P < 0.05). CONCLUSION: There is obvious improvement function of warming-reinforcing acupuncture combined with rehabilitation training on the early motor function of hemiparalysis patients caused by ischemic brain stroke, and the function is better than that of simple rehabilitation training.