Browsing by Author "Meenakshi K. Singh"

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A dual epitope-imprinted polymer@AuNP-MoS2 nanosheets-EQCM sensor for antibody free detection of SipD protein of Salmonella typhi bacteria with high selectivity
(Elsevier B.V., 2025) Akriti Srivastava; Ashish Kumar Kushwaha; Pinky Sagar; Anirban Parida; Roop Shikha Singh; Sanjay Kumar Srivastava; Richa Raghuwanshi; Gopal Nath; Meenakshi K. Singh
Dual-epitope imprinted EQCM sensor for selective and sensitive detection of Salmonella typhi bacterial protein is fabricated on gold nanoparticle decorated MoS2 nanosheets (AuNPs-MoS2NSs). Salmonella invasive protein D (SipD) binds to the needle protein and appears capable of interacting with the translocon complex to infect the host. Potential B cell antigenic epitope sequences from bacterial tip protein, SipD were intentionally tagged with cysteine and are used as dual templates to fabricate MIP sensor using methacryloyloxyethyl phosphorylcholine (MPC), benzyl methacrylate (BMA) and methacrylic acid (MAA) as monomers and N , N ′-methylene- bis -acrylamide as a crosslinker. The monomers chosen through docking produced a DEIP-EQCM sensor. The sensor was able to show specific binding towards the blood samples of infected patients, even in the presence of ‘matrix’ of ‘real’ samples and other plasma proteins. It has shown excellent specificity, sensitivity and selectivity in sensing range of 100–1000 nM with detection limit 1.65 nM (Epitope I) and 0.025 nM (Epitope II) and limit of quantification as 5.03 nM (Epitope I) and 0.075 nM (Epitope II) for the two epitope sequences imprinted. Sip D protein binding was substantiated by SDS-PAGE analysis. The repetitive experimental runs could not mutilate the specific geometries of respective imprinted cavities and the DEIP-EQCM sensor can be proposed for antibody free detection of Sip D protein. © 2025 The Authors.
A polypyrrole-coated GCE sensor for sensitive detection of 5-fluorouracil via molecular imprinting
(Royal Society of Chemistry, 2025) Manjeet Harijan; Akriti Srivastava; Meenakshi K. Singh
Cytotoxic drug 5-fluorouracil (5-FU) is a fluorine derivative of uracil; it is one of the most significant medications used to treat cancers of the stomach, breast, colon, pancreas, and cervical regions. Here, a reliable, rapid, highly sensitive and selective method is proposed for determining 5-FU in real samples. In this study, a molecularly imprinted polymer (MIP) based electrochemical sensor is designed for the sensitive and selective determination of 5-FU. The MIP was developed by the electropolymerization of a pyrrole thin film around template molecules (5-FU) on a glassy carbon electrode (GCE). The sensor was characterized after each stage of fabrication using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The MIP sensor exhibited a wide linear range for determining 5-FU from 2-42 μM. The developed sensor achieved a limit of detection (LOD) and limit of quantification (LOQ) of 0.605 μM and 1.834 μM, respectively. The applicability of the proposed sensor was examined for 5-FU determination in real samples. The MIP sensor exhibited excellent selectivity, repeatability, stability, and commercialization potential for 5-FU detection. Furthermore, the proposed method offers significant advantages over existing electrochemical techniques for 5-FU detection. This method provides single-step preparation alongside simple template molecule removal by cyclic voltammetry scans and does not need any extracting solvents. © 2025 The Royal Society of Chemistry.
Computational designing and synthesis of epitope imprinted sensor with zwitterionic polymeric matrix for sensitive, specific and selective sensing of protein
(Elsevier Inc., 2025) Akriti Srivastava; Richa Raghuwanshi; Meenakshi K. Singh
Lactoferrin (Lf) protein is a member of the transferrin family, present in mature milk, transitional milk, and colostrum milk. It has antibacterial, antiviral, immunomodulatory, anticancer, and prebiotic properties, and vital in many biomedical and biotechnological applications, and also serve as biomarker for several disorders, viz. Alzheimer's disease, inflammatory bowel disease, subclinical mastitis, dry eye disease, etc. Here, N-terminal region peptide of Lf is chosen for epitope imprinting. This epitope sequence was imprinted on electrochemical quartz crystal microbalance (EQCM) electrode using multiple monomer approach. The monomers were chosen through in silico molecular docking for to select appropriate set of monomers for chosen peptide sequence as target analyte. A zwitterionic monomer 2-methacryloyloxyethyl phosphorylcholine (MPC) with benzyl methacrylate (BMA) and 4-aminothiophenol (4-ATP) were predicted for crafting imprinted polymer matrix. On extraction of the peptide (epitope) sequences, imprinted cavities were capable to selectively and specifically capture intended peptide (epitope) sequences in laboratory samples as well as ‘real’ samples. Selectivity of sensor was examined through mismatched peptide sequences and certain plasma proteins also. The sensor was able to show specific binding towards the ‘real’ samples of milk, even in the presence of ‘matrix’ and other proteins. The limit of detection and quantification was found to be 5.25 nM and 17.51 nM respectively with imprinting factor as 10.91. Good analytical performance was shown by the devised technique, high sensitivity and selectivity with no matrix interference. © 2025 Elsevier B.V.
Machine learning-enhanced detection of chlorpyrifos using molecularly imprinted polymer-coated optical fibers
(Elsevier B.V., 2025) Ankit Mishra; Rajiv Maurya; Suraj Prakash; Chandan Singh Yadav; Abhishek Upadhyay; Ritu Singh; Meenakshi K. Singh; Vivek B. Singh
This paper explores the use of large core declad optical fibers coated with molecularly imprinted polymers for chlorpyrifos detection, a key marker of organophosphate pesticides. The performance of sensor is evaluated using artificial neural networks and principal component analysis. By varying the declad length, the performance of molecularly imprinted polymer-coated fibers is compared to uncoated fibers, and both are used to identify commercial and pure samples of chlorpyrifos pesticides. Molecularly imprinted polymer-coated declad fiber sensors particularly those with longer declad lengths, exhibit significantly lower detection limits and higher sensitivity. The obtained maximum sensitivity, and minimum detection limit at 4 cm declad fiber length are 0.0027 mV/nM and 60.70 nM respectively. The results obtained also demonstrate that the artificial neural network can make an accurate prediction and the principal component analysis validates the efficacy of our molecularly imprinted polymer-coated fibers in chlorpyrifos detection. © 2025 Elsevier B.V.
Perspective towards nanomaterial-integrated molecularly imprinted polymer (MIP)-based electrochemical sensors for protein biomarkers detection: A review
(Elsevier Inc., 2025) Ritu Singh; Meenakshi K. Singh
This review discusses elegant molecularly imprinted polymer-based electrochemical sensors, as well as the significance of nanomaterials incorporation for sensitive and selective detection of protein biomolecules. Biomarkers are naturally occurring proteins, genes, or small biological molecules found in biological fluids to indicate a biological state. Proteins are one of the ideal target biomarkers as they are indicative of many disease states. Therefore, protein detection is important in various fields such as diagnosis and biomedical applications. MIPs are one of the best synthetic diagnostic tools for the selective detection of protein biomarkers. However, MIPs for proteins as macromolecules encounter difficulties moving in and out of the polymer matrix, which hinders their detection at minute concentrations. Therefore, MIP film formation on electrode surfaces with controlled film thickness for electrochemical detection of proteins has gained interest due to the ease of process and performance. In recent times, nanotechnology has attracted tremendous attention. One promising application is using nanomaterials to amplify signals in constructing high-performance electrochemical sensing platforms for ultra-sensitive detection of targeted analytes. Nanomaterials provide a high surface area-to-volume ratio and excellent electronic properties, allowing easy accessibility of protein biomolecules to the imprinted polymer matrix as well as enhancing the sensitivity and detection limit. Therefore, this review especially focuses on the nanomaterials integrated electrochemical MIPs for sensitive and selective detection of protein in biological fluids. © 2025 Elsevier B.V.
Unravelling the Potential of Zwitterionic Polymers in Molecular Imprinting
(American Chemical Society, 2025) Meenakshi K. Singh; Akriti Srivastava; Moumita Mandal
Molecularly imprinted polymers (MIPs) are a class of molecular receptors that are the closest imitation of biological receptors. They are often called “artificial enzymes”. The capability of the MIPs to bind bioactive molecules under specific conditions creates molecular imprinting technology as having considerable potential for customized applications. Polymerization in the presence of a “template” molecule with the assistance of monomers, cross-linkers, and initiators leads to MIPs on extraction of the template molecule from the polymeric matrices. Conventionally neutral monomers were utilized for molecular imprinting. Recently, zwitterionic polymers, having innumerable advantages over nonionic polymers, were realized to be an advantageous choice as a polymeric matrix for imprinting. This review article presents an overview of sulfobetaine, carbobetaine, and phosphobetaine polymers as imprinting matrices for a range of template(s). Zwitterionic polymers are accomplished with biocompatibility, low cytotoxicity, negligible immunogenicity, systematic stability, and long circulation time, and can alleviate quick recognition by the immune system and delayed blood clearance from the body. They can be a fitting candidate for imprinting, especially of biomolecules. The molecular imprinting work on zwitterionic polymers is presented here, which will encourage researchers working in this area. © 2025 American Chemical Society.