Universal Capacitance(Impedance) Sensors Based On Molecularly Imprinted Cryogels

Molecular imprinting has become an important means of studying molecular recognition and regulation.Due to the application of template molecules,molecularly imprinted polymers(MIPs)contains a large number of recognition cavities,pairing with the template one by one.These sites retain the "memory" of the template molecules,having a strong affinity and recognizing power.Each cavity is Molecularly imprinted cryogels are macroporous polymeric materials with three-dimensional network structures synthesized in frozen states.As numerous imprinted sites exist,a small membrane electrode made of MIP becomes a huge array of "molecular capacitors".It generates a prominent electrochemical signal to detect the template over a wide linear range at very low detection limits.This paper perfects and expands the cryogenic polymerization method,taking advantage of the imprinted cryogels to recognize charged molecules,and deeply studies the "antibody+molecular capacitor" property of imprinted sites.On this basis,highly sensitive and highly selective portable sensors have been constructed.On this basis,a portable electrochemical sensor was developed to realize efficient,fast and low-cost analysis and detection of proteins and charged drugs.Part ? Impedance Sensors based on Protein Imprinted CryogelsAccording to the previously reported methods,bovine serum albumin(BSA)and bovine hemoglobin(BHb)imprinted cryogels were prepared and used for the detection of template proteins.The cryogels of polyacrylamide modified by acrylic acid and diallylamine.Studies have shown that when MIP is used as an artificial antibody for the preparation of electrochemical sensors,high sensitivity and selectivity are achieved simultaneously.The sensor prepared from molecularly imprinted cryogel has high specificity,high sensitivity,simple operation and good reproducibility.The macroporous polymer shows similar antibody sensitivity to template protein.The linear ranges are calculated as 1.50×10-16-1.50×10-12 mol·L-1 for BSA,and 150×10-17-1.50×10-12 mol·L-1 for BHb.The detection limits are 7.20×10-18 mol·L-1 ? 8.50?10-18 mol·L-1.The concentration of template protein was successfully determined in actual serum samples The experimental results achieved the expected results,and the results were satisfactory.Part ? Portable Capacitive Sensor based on Charged Molecule Imprinted CryogelsImprinted cryogels can also be used to determine samll charged compounds.Due to the use of ionizable monomers such as diallylamine and sodium vinyl sulfonate(SVS),these polymers are slightly charged.With the addition of a charged template,the amino or sulfonate groups are directed to the imprinting site.During molecular recognition,the polymer charge is neutralized by that of the template,resulting in a significant change in the dielectric constant.Therefore,the LCR table was used to successfully detect the molecular recognition signal,and realize the high sensitivity and selectivity analysis of the charged and ionizable drugs such as aspirin(ASP),proknolol hydrochloride(PLP)and glyphosate(GLP).The linear ranges are calculated as 5.50×10-13-10-9 mol·L-1 for asprin,3.39×10-13-10-6 mol·L-1 for propranolol and 5.89×10-16-10-6 Mol·L-1 for glyphosate.The detection limits are 1.68×10-13 mol·L-1,3.02×10-13 Mol·L-1 and 1.94×10-16 Mol·L-1.Part ? Portable Capacitive Sensors based on Glucose Imprinted CryogelsGlucose is an important biomolecule.It is neutral and usually does not ionize.In order to verify the possibility of the detection of neutral compounds with MIP cryogels,glucose is selected as the template to prepare MIP and make a sensor,leading into posotive results.At a pH of 9.60,glucose molecules and APBA monomers form an uncharged complexes,therefor strengthen the interaction of the imprinted site and the template.An imprintd cryogel based portable sensor has been successfully used in the detection of glucose,with a wide linear range and low detection limits.The linear range is calculated as 0.056-56 mM.The detection limits is 0.011 mM.Experiments proved that the sensor has good anti-interference ability,and can be used in the determination of actual samples such as tears and saliva etc.