A high sensitive epitope imprinted electrochemical sensor for bovine serum albumin based on enzyme amplifying.

To improve the sensitivity of the molecular imprinting sensor detection of protein, a new strategy based on enzyme amplification was proposed. The determination of bovine serum albumin (BSA) was achieved by using the epitope imprinted techniques coupling with electrochemical measurement method. Nonapeptide, separated from BSA, was selected as a template molecule to prepare the molecularly imprinted polymer (MIP) film, and it could bind with the cavities of the MIP. By the use of epitope imprinted techniques, BSA can be recognized by the MIP via the nonapeptide on the surface of BSA. The synthesized horseradish peroxidase-labeled nonapeptide (HRP-nonapeptide) can also be recognized by the MIP. After the competitive reaction between HRP-nonapeptide and BSA, the enzymatic reaction derived from labeled HRP on the H2O2-hydroquinone system make the electrochemical current of hydroquinone change, then the concentration of BSA can be indirectly determined. BSA in the range of 1.0-150 ng/mL exhibited a linear relationship with the differential pulse voltammetric current variation and the detection limit was 0.02 ng/mL. The sensor has high sensitivity, good selectivity, and reproducibility. It has been applied to the determination of residual bovine serum albumin in human rabies vaccine with the recovery rate of 98.3%-102.5%.

A molecularly imprinted electrochemiluminescence sensor based on the mimetic enzyme catalytic effect for ultra-trace Ni2+ determination.

A novel molecularly imprinted polymer (MIP) electrochemiluminescence (MIP-ECL) sensor was developed for the highly sensitive and selective determination of ultra-trace levels of Ni2+. The complex Ni2+-dimethylglyoxime (Ni-DMG) was chosen as the template molecule to construct the MIP and then acted as a mimetic enzyme to catalyse the oxidisation of luminol to enhance the ECL signal. When the imprinted cavities were occupied by Ni-DMG in the rebinding process, the ECL intensities produced by the luminol-H2O2 ECL system on the MIP-modified electrode surface increased with increased concentration of the Ni-DMG complex. The highly sensitive determination of Ni2+ was achieved through a catalytic reaction. This technique could be used for the quantitative analysis of Ni2+ with concentrations from 3.0 × 10-12 mol L-1 to 6.0 × 10-9 mol L-1. The detection limit was 1.01 × 10-12 mol L-1, which is much lower than that reported previously. In addition, the allowable amounts of interference ions in the MIP-ECL sensor were higher than that in other common molecularly imprinted sensors because of its excellent recognition of 3D cavity-to-complex molecules and ligand-to-metal ions. This method was successfully used to determine Ni2+ in real samples, such as apples, carrots and grapes, and has been proven feasible for practical applications.

Protein synergistic action-based development and application of a molecularly imprinted chiral sensor for highly stereoselective recognition of S-fluoxetine.

In order to improve the recognition performance of MIPs sensors in chiral drug enantiomers, a novel a highly selective molecular recognition method based on protein-assisted immobilization of chiral molecular conformation was developed. S-fluoxetine (S-FLX) as the target chiral molecule, human serum albumin (HSA), which has a high affinity and strong interactions with S-FLX, was screened from 11 proteins to serve as an auxiliary recognition unit for the fixation of chiral conformation. By incorporating HSA into the preparation of molecularly imprinted polymers (MIPs), the natural chirality and high stereoselectivity of the protein were leveraged for the induction and fixation of the stereo conformation of S-FLX, refinement of internal structures of the imprinted cavities. The sensor exhibited excellent chiral recognition ability and high detection sensitivity. The changes of probe signal intensity of the MIPs/HSA sensor were positively correlated with the logarithmic concentration of S-FLX in the range of 1.0 × 10-16-1.0 × 10-11 mol L-1, where a detection limit of 6.43 × 10-17 mol L-1 was achieved (DL = 3δb/K). The selectivity of MIPs/HSA sensor in recognizing S-FLX was increased by 18.5 times and the sensitivity was increased by 2.6 times after the incorporation of HSA. The developed sensor was successfully used for the analysis of S-FLX in fluoxetine hydrochloride capsules.

Development of Levo-Lansoprazole Chiral Molecularly Imprinted Polymer Sensor Based on the Polylysine-Phenylalanine Complex Framework Conformational Separation.

The efficacies and toxicities of chiral drug enantiomers are often dissimilar, necessitating chiral recognition methods. Herein, a polylysine-phenylalanine complex framework was used to prepare molecularly imprinted polymers (MIPs) as sensors with enhanced specific recognition capabilities for levo-lansoprazole. The properties of the MIP sensor were investigated using Fourier-transform infrared spectroscopy and electrochemical methods. The optimal sensor performance was achieved by applying self-assembly times of 30.0 and 25.0 min for the complex framework and levo-lansoprazole, respectively, eight electropolymerization cycles with o-phenylenediamine as the functional monomer, an elution time of 5.0 min using an ethanol/acetic acid/H2O mixture (2/3/8, V/V/V) as the eluent, and a rebound time of 10.0 min. A linear relationship was observed between the sensor response intensity (ΔI) and logarithm of the levo-lansoprazole concentration (l-g C) in the range of 1.0 × 10-13-3.0 × 10-11 mol/L. Compared with a conventional MIP sensor, the proposed sensor showed more efficient enantiomeric recognition, with high selectivity and specificity for levo-lansoprazole. The sensor was successfully applied to levo-lansoprazole detection in enteric-coated lansoprazole tablets, thus demonstrating its suitability for practical applications.

Research and Application of Highly Selective Molecular Imprinting Technology in Chiral Separation Analysis.

Since residual chiral pollutants in the environment and toxic or ineffective chiral components in drugs can threat human health, there is an urgent need for methods to separation and analyze chiral molecules. Molecular imprinting technology (MIT) is a biomimetic technique for specific recognition of analytes with high potential for application in the field of chiral separation and analysis. However, since MIT has some disadvantages when used for chiral recognition, such as poor rigidity of imprinted materials, a single type of recognition site, and poor stereoselectivity, reducing the interference of conformationally and structurally similar substances to increase the efficiency of chiral recognition is difficult. Therefore, improving the rigidity of imprinted materials, increasing the types of imprinted cavity recognition sites, and constructing an imprinted microenvironment for highly selective chiral recognition are necessary for the accurate identification of chiral substances. In this article, the principle of chiral imprinting recognition is introduced, and various strategies that improve the selectivity of chiral imprinting, using derivative functional monomers, supramolecular compounds, chiral assembly materials, and biomolecules, are reviewed in the past 10 years.

Highly sensitive and doubly orientated selective molecularly imprinted electrochemical sensor for Cu(2.).

Studies on molecularly imprinted electrochemical sensors for metal ions determination have been widely reported. However, the sensitivity and selectivity of the sensors needs to be improved urgently. In the current work, a novel molecularly imprinted electrochemical sensor was originally developed for selective determination of ultratrace Cu(2+) by combining the metal-ligand chelate orientated recognition with enzyme amplification effect. The detection relied on a competition reaction between Cu(2+)-glycine (Cu-Gly) and horse radish peroxidase (HRP)-labeled Cu-Gly on the imprinted polymer membrane modified electrode. The sensitivity of this sensor was promoted by enzyme amplification. Selectivity was improved by the double-specificity derived from ligand-to-metal ion and metal-ligand chelate orientated recognition of 3D imprinted cavities. This technique was quantitatively sensitive to Cu(2+) concentrations ranging from 0.5nmol/L to 30nmol/L, with a detection limit of 42.4pmol/L. which was lower than those in most of the reported methods. The allowable amounts of interference ions were higher when it compared to other common molecularly imprinted sensors. Moreover, the results of assaying several real samples have proven its feasibility for practical applications.