•Novel pH double-responsive imprinted magnetic microspheres have been prepared.•The synergistic effect of pH-sensitive monomer and boronate affinity was first reported.•Rapidly Capturing/releasing of OVA could be modulated by changing pH.•High absorption ability was achieved within about 10 min.As biomarkers of many diseases, glycoproteins are of great significance to clinical diagnostics. However, the determination of low abundant glycoproteins in complex biological samples without any pretreatment process is still a problem. In this study, a rapid and convenient separation method for highly efficient enrichment of glycoproteins is reported, based on pH double-responsive imprinted magnetic microspheres. Thin imprinted polymer shells were fabricated onto the surface of magnetic microspheres by free radical polymerization, using 2-(Dimethylamino) ethyl methacrylate as pH-sensitive monomer, 4-vinylphenylbronic acid as boronate affinity monomer, and ovalbumin (OVA) as template molecule. Combining the advantages of pH-sensitive monomer and boronate affinity monomer, rapidly capture-release of OVA could be modulated by changing solution pH. Moreover, high absorption ability (81.2 mg/g) was achieved within about 10 min. This study provided responsible way to imprint glycoproteins and showed great potential for glycoprotein detection in clinical diagnostic.pH double-responsive magnetic microspheres with shrinking-swelling molecularly imprinted cavities for glycoproteins separation were prepared, which use synergistic effect of boronate affinity and pH-responsive hydrogels.Download high-res image (234KB)Download full-size image

•Robust and stable molecularly imprinted hollow fiber membranes were prepared.•Triple recognition based on imprinted membrane and dual chiral additives was achieved.•A selectivity factor for enantioseparation of (S)-amlodipine reached 1.98.•The cross-flow experiment provided a potential large-scale production process.In this study, a triple recognition chiral extraction process has been developed to separate (S)-amlodipine from racemic raw medicine, based on the combination of molecularly imprinted hollow fiber membrane and cross-flow biphasic recognition extraction. The chiral separation process was operated in a dismountable hollow fiber module coated with molecularly imprinted polymer, and the cross-flow extraction was applied with d-tartaric acid in feed phase and sulfobutyl ether-β-cyclodextrin in stripping phase. The synergistic effect of molecularly imprinted polymer and dual chiral additives was investigated, and excellent enantioseparation ability with a selectivity factor of 1.98 was obtained. Mathematical model of S/R = 0.598e0.150NTU for racemic amlodipine separation by molecularly imprinted hollow fiber membrane extraction was established. The optical purity for amlodipine is up to 90% when 4 hollow fiber membrane modules of 25 cm in length in series are used. The triple recognition process strongly enhanced the separation selectivity; therefore it may bring about the potentially application for large-scale production of pure enantiomeric compound.

•An interference-free and label-free miRNA detection strategy was proposed.•Magnetic silicon microsphere (MNP)-rGO-based sandwich probe was designed.•A high signal-to-background ratio and the sensitivity and selectivity were obtained.An interference-free and label-free sensing platform was developed for the highly sensitive detection of microRNA-21 (miRNA-21) in vitro by magnetic silicon microsphere (MNP)-reduced graphene oxide (rGO)-based sandwich probe. In this method, DNA capture probes (P1) were connected with MNPs at the 5′ end and hybridized with completely complementary target miRNA. Subsequently, rGO was retained and induced the fluorescence quenching in the supernatant. Through the magnetic separation, the supernatant environment was simplified and the interference to analytical signal was eliminated. When DNA capture probe-modified magnetic silicon microspheres (MNP-P1) were adsorbed through rGO in the absence of a target and formed a sandwich structure, the formed nanostructure was easily removed from the solution by a magnetic field and the fluorescence intensity was maximally recovered. This proposed strategy, which both overcame the expensive and cumbersome fluorescent labeling, and eliminated interference to analytical signal for guaranteeing high signal-to-background ratio, exhibited high sensitivity with a detection limit as low as 0.098 nM and special selectivity toward miRNA-21. The method was potentially applicable for not only detection of miRNA-21 but also various biomarker analyses just by changing capture probes.An interference-free and label-free sensing platform was developed for microRNA-21 detection. DNA capture probes (P1) were connected with MNPs and hybridized with completely complementary target miRNA. Subsequently, rGO was retained and induced the fluorescence quenching in the supernatant. When DNA capture probe-modified magnetic silicon microspheres (MNP-P1) were adsorbed through rGO in the absence of a target and formed a sandwich structure, the formed nanostructure was easily removed from the solution by a magnetic field and the fluorescence intensity was maximally recovered.Download high-res image (86KB)Download full-size image

We describe a facile quencher-free fluorescence strategy for rapid detection of microRNAs (miRNAs) by using a novel double-strand displacement sensor. The sensor is designed with an outstanding 2-aminopurine (2-AP) fluorophore as a probe and a predesigned cDNA, which can completely complement the target miRNA and partly complement the 2-AP probe. When the target miRNA is added, the cDNA can be competed off from the cDNA\2-AP probe duplex, thereby forming a cDNA\RNA heteroduplex. The free 2-AP probe induces an increase in the fluorescent signal. A limit of detection of 5 nM and a wide linear range from 5 to 1000 nM (R2 = 0.9971) are achieved by this assay. The rapid detection strategy can be accomplished within 2 h without expensive nanoparticles and complicated instruments for the whole procedure, thus, offering a significant potential for clinical application.

•First report on MIP-based assay for fluorescence detection of virus.•Surface imprinting is advantageous due to the easy elution and rebinding.•JEVIPs were able to specifically capture the target JEV via the recognition cavities.•Sensitive fluorescent detection in water was offered for JEV with wide linear range.A novel virus-recognition fluorescent sensor based on virus-imprinted polymers (VIP) for highly selective and highly sensitive detection of Japanese encephalitis virus (JEV) was presented. The virus-imprinted method went beyond simple shape imprinting through surface imprinting with magnetic silicon microspheres acting as carrier materials and tetraethyl orthosilicate (TEOS) functioning as building blocks. The resulting VIP film could selectively capture target JEV via recognition cavities, and a high imprinting factor of 2.98 was achieved. Furthermore, fast magnetic separation and highly sensitive fluorescent detection in water were offered for JEV, showing a good linearity within 2.5–45 nM (R2 = 0.9948). Finally, the specificity study confirmed that the virus-imprinted magnetic silicon microspheres demonstrated excellent selectivity for JEV in several different types of virus.JEVIP, which was applied as artificial recognizer and could specially capture the target JEV in several different types of virus.

The analytical resolution of ketoconazole (KTZ) enantiomers was performed by high-performance liquid chromatography with sulphobutylether-β-cyclodextrin (SBE-β-CD) as a chiral mobile phase additive (chiral selector). Some important factors affecting the resolution of KTZ enantiomers were investigated. In addition, the molecular interaction between KTZ and SBE-β-CD was studied using the UV absorption spectrum and HPLC for an understanding of the resolution process. The results show that the type and concentration of the chiral mobile phase additive, the pH of the mobile phase and the volume fraction of methanol (ϕMeOH) in the mobile phase all have a clear influence on the resolution of KTZ enantiomers. Under optimal conditions, namely the use of 0.5 mmol L−1 SBE-β-CD as the chiral mobile phase additive, pH of 4.0 and ϕMeOH in the mobile phase of 0.6, KTZ enantiomers are resolved with a resolution of 3.74. SBE-β-CD can bind to KTZ with a stability constant of 1157. The chromatographic method can provide the complexation stability constants of (+)-KTZ with SBE-β-CD (K(+)) and (−)-KTZ with SBE-β-CD (K(−)). The intrinsic enantioselectivity was calculated from the K(+) to (K(−)) ratio as 1.34.

A new process has been developed to separate ketoconazole (KTZ) enantiomers by membrane extraction, with the oppositely preferential recognition of hydrophobic and hydrophilic chiral selectors in organic and aqueous phases, respectively. This system is established by adding hydrophobic l-isopentyl tartrate (l-IPT) in organic strip phase (shell side) and hydrophilic sulfobutylether-β-cyclodextrin (SBE-β-CD) in aqueous feed phase (lumen side), which preferentially recognizes (+)-2R,4S-ketoconazole and (−)-2S,4R-ketoconazole, respectively. The studies performed involve two enantioselective extractions in a biphasic system, where KTZ enantiomers form four complexes with SBE-β-CD in aqueous phase and l-IPT in organic phase, respectively. The membrane is permeable to the KTZ enantiomers but non-permeable to the chiral selector molecules. Fractional chiral extraction theory, mass transfer performance of hollow fiber membrane, enantioselectivity and some experimental conditions are investigated to optimize the separation system. Mathematical model of I/II = 0.893e0.039NTU for racemic KTZ separation by hollow fiber extraction, is established. The optical purity for KTZ enantiomers is up to 90% when 9 hollow fiber membrane modules of 30 cm in length in series are used.Graphical abstractHighlights► Biphasic recognition add two chiral selectors into two phases, respectively. ► Membrane extraction can overcome the disadvantages of liquid–liquid extraction. ► The article combines the advantages of biphasic recognition and membrane extraction. ► The article builds a mathematical model of separation of KTZ enantiomers.

A sensitive electrochemical method was developed for the determination of doxorubicin at a glassy carbon electrode (GCE) modified with a nano-titania (nano-TiO2)/nafion composite film. Nano-TiO2 was dispersed into nafion to give a homogeneous suspension. After solvent evaporation, a uniform film of nano-TiO2/nafion composite was obtained on the GCE surface. The nano-TiO2/nafion composite film modified GCE exhibited excellent electrochemical behavior toward the reduction of doxorubicin. Compared to the reduction of doxorubicin at the bare GCE, the reduction current of doxorubicin at the nano-TiO2/nafion composite film modified GCE was greatly enhanced. Based on this, a novel voltammetric method was applied to the determination of doxorubicin. The experimental parameters that influence the reduction current of doxorubicin, were optimized. Under optimal conditions, a linear response of doxorubicin was obtained in the range from 5.0 × 10−9 to 2.0 × 10−6 mol L−1 (R = 0.998) and with a limit of detection (LOD) of 1.0 × 10−9 mol L−1(S/N = 3). The RSD of the measurement is 4.7%, and the RSD of the inter-electrode is of 5.1% which indicate the reproducibility of this method. The current response decreased only by around 3.8% of its initial response after 2 weeks exposing the electrode in air. The procedure was applied to assay doxorubicin in human plasma samples with the recoveries of 94.9–104.4%.

A new process has been developed to separate ketoconazole (KTZ) enantiomers by membrane extraction, with the oppositely preferential recognition of hydrophobic and hydrophilic chiral selectors in organic and aqueous phases, respectively. This system is established by adding hydrophobic l-isopentyl tartrate (l-IPT) in organic strip phase (shell side) and hydrophilic sulfobutylether-β-cyclodextrin (SBE-β-CD) in aqueous feed phase (lumen side), which preferentially recognizes (+)-2R,4S-ketoconazole and (−)-2S,4R-ketoconazole, respectively. The studies performed involve two enantioselective extractions in a biphasic system, where KTZ enantiomers form four complexes with SBE-β-CD in aqueous phase and l-IPT in organic phase, respectively. The membrane is permeable to the KTZ enantiomers but non-permeable to the chiral selector molecules. Fractional chiral extraction theory, mass transfer performance of hollow fiber membrane, enantioselectivity and some experimental conditions are investigated to optimize the separation system. Mathematical model of I/II = 0.893e0.039NTU for racemic KTZ separation by hollow fiber extraction, is established. The optical purity for KTZ enantiomers is up to 90% when 9 hollow fiber membrane modules of 30 cm in length in series are used.Graphical abstractDownload full-size imageHighlights► Biphasic recognition add two chiral selectors into two phases, respectively. ► Membrane extraction can overcome the disadvantages of liquid–liquid extraction. ► The article combines the advantages of biphasic recognition and membrane extraction. ► The article builds a mathematical model of separation of KTZ enantiomers.