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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 (NH

Rapid detection of malachite green (MG) by fluorescence probes of CdTe quantum dots (QDs) coated with molecularly imprinted polymer (MIP) has been reported, but low sensitivity, slow response and narrow linear range were the main disadvantages for these MIP@QDs probes. Here, an ultra-sensitive ratiometric fluorescence probe based on self-assembly functionalized polystyrene (PS) and core-shell structured MIP was developed for the detection of MG in fish. After modified with poly(diallyldimethylammonium chloride) and hexadecyl trimethyl ammonium bromide, CdTe QDs and silica encapsulated carbon quantum dots (CDs@SiO2) with negative charges, used as detection and reference fluorophores, were respectively self-assembled on the surface of PS to form PS-QDs&CDs. And a core-shell structured MIP layer was fabricated on the surface of PS-QDs&CDs to form a ratiometric fluorescence probe of MIP@PS-QDs&CDs with sol-gel method using MG, (3-aminopropyl)triethoxy-silan and tetraethyl orthosilicate as template, functional monomer and cross-linker, respectively. With intensive fluorescence densities of QDs&CDs in nucleus, the fluorescence emission of probe at λem of 630 nm could be linearly quenched by MG, while the fluorescence emission at λem of 430 nm remained unchanged. The probe of MIP@PS-QDs&CDs owned good fluorescence stability (RSD ≤2.3%), fast response time (5 min), wide linear range (0.1–32 μmol L−1) and low detection limit (5.6 μg kg−1), and has been applied to the detection of MG in fish samples with recoveries of 94.3–110.2%. The result validated that the as-prepared probe of MIP@PS-QDs&CDs had an excellent performance for MG detection in fish samples.

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.

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.

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 practical aptaprobe for sulfadimethoxine (SDM) detection was established. Based on the electrostatic reaction, a duplex of aptamer and poly(diallyldimethylammonium chloride) (PDDA) was formed, which prevented the quenching effect of PDDA on the fluorescence of CdTe quantum dots (QDs). But the specifically binding of aptamer to SDM might result in free PDDA released and the fluorescence was quenched. Based on the fluorescence aptaprobe, SDM was quantitatively detected by measuring the fluorescence at 530 nm with a linear range of 25–300 ng mL−1, and the limit of detection was 2.24 ng mL−1 based on 3σ/K (n = 9). The aptaprobe was applied to SDM detection with recoveries of 94.2 %–113 % and 104 %–118 % for seawater and fish, respectively. The results showed that the fluorescence aptaprobe was simple and convenient for the rapid detection of SDM residue in water and fish samples.

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.

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.

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.

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.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.The effective rate of group A (87.5%, 35/40) superior to that of group B (67.5%, 27/40) (P0.05). The neurological functional deficit scores, Fugl-Meyer score, MAS and Barthel Index of both groups were improved after treatment (P0.01, P0.05), and the improved degree of group A was better than that of group B (P0.01, P0.05).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.