Detection of p53 gene point mutation using sequence-specific molecularly imprinted PoPD electrode

Molecularly Imprinted Electrochemical Sensors: Analytical and Pharmaceutical Applications Based on Ortho-Phenylenediamine Polymerization

Background:

The molecular imprinting technique has been applied in many fields including separation, artificial antibody mimics, catalysis, sensing studies, and drug delivery. The reasons for the popularity of this technique among the researchers are high selectivity due to the cavities that are formed on the polymer surface for the specific analyte, high robustness, high durability under extreme conditions and low cost. When these advantages are combined with the advantages of electrochemical methods such as rapid response time, ease of use, cheapness and miniaturizability, Molecularly Imprinted Polymer (MIP) based electrochemical sensors turn out to be a widely-preferred sensing tool.

Objective:

This article provides the reader with information on MIP-based electrochemical sensors and reviews the applications of the MIP sensors prepared by electropolymerization of orthophenylenediamine, a monomer whose mechanical and chemical stability is very high.

Results and Conclusion:

The literature survey summarized in this review shows that cyclic voltammetry is the most widely preferred electrochemical technique for electropolymerization of o-PD. The media chosen is generally acetate or phosphate buffers with different pH values. Although there are numerous solvents used for template removal, generally methanol and NaOH have been chosen.

Molecularly Imprinted Materials for Selective Biological Recognition

Molecular imprinting is an approach of generating imprinting cavities in polymer structures that are compatible with the target molecules. The cavities have memory for shape and chemical recognition, similar to the recognition mechanism of antigen-antibody in organisms. Their structures are also called biomimetic receptors or synthetic receptors. Owing to the excellent selectivity and unique structural predictability of molecularly imprinted materials (MIMs), practical MIMs have become a rapidly evolving research area providing key factors for understanding separation, recognition, and regenerative properties toward biological small molecules to biomacromolecules, even cell and microorganism. In this review, the characteristics, morphologies, and applicability of currently popular carrier materials for molecular imprinting, especially the fundamental role of hydrogels, porous materials, hierarchical nanoparticles, and 2D materials in the separation and recognition of biological templates are discussed. Moreover, through a series of case studies, emphasis is given on introducing imprinting strategies for biological templates with different molecular scales. In particular, the differences and connections between small molecular imprinting (bulk imprinting, "dummy" template imprinting, etc.), large molecular imprinting (surface imprinting, interfacial imprinting, etc.), and cell imprinting strategies are demonstrated in detail. Finally, future research directions are provided.

Oligonucleotide Analogs and Mimics for Sensing Macromolecular Biocompounds

Living organisms create life-sustaining macromolecular biocompounds including biopolymers. Artificial polymers can selectively recognize biocompounds and are more resistant to harsh physical, chemical, and physiological conditions than biopolymers are. Due to recognition at a molecular level, molecularly imprinted polymers (MIPs) provide powerful tools to correlate structure with biological functionality and are often used to build next-generation chemosensors. We envision an increasing emergence of nucleic acid analogs (NAAs) or biorelevant monomers built into nature-mimicking polymers. For example, if nucleobases bearing monomers arranged by a complementary template are polymerized to form NAAs, the resulting MIPs will open up novel perspectives for synthesizing NAAs. Despite their usefulness, it is still challenging to use MIPs to devise adaptive biomaterials and to implement them in point-of-care testing.

2-Methylpyridine-1-ium-1-sulfonate as an Inducer of Apoptosis and Cell Cycle Arrest: A comparative in vitro and Computational Study

"Let food be thy medicine and thy medicine be thy food" was expressed by Hippocrates and the health benefits of medicinal plants and natural products have been considered by humans since historic times. The current study aims to investigate the anti-cancer activity of 2-Methylpyridine-1-ium-1-sulfonate (MPS) isolated from bulbs of Allium hirtifolium. The MPS compound (in a dose-dependent manner) induced arrest the AGS cells in G1 and G2/M phases, and Caco-2 cells in G1 and S phases. These findings were associated with the down-regulation of cyclin D1, CDK4, and up-regulation of p21, p27 and p53. According to the morphological observations and DNA fragmentation assay, the MPS compound induced apoptosis in both cell lines, and also cause a significant increase in the expression of Bax/Bcl-2. In this context, our molecular docking results unveiled that the MPS compound has considerable affinity to interact with the minor groove of ctDNA and also with cell cycle kinases. To approve and find the accurate MPS mode of action against cancer cell lines (especially in gastrointestinal cancer) further studies is highly recommended.

Programmed Transfer of Sequence Information into a Molecularly Imprinted Polymer for Hexakis(2,2'-bithien-5-yl) DNA Analogue Formation toward Single-Nucleotide-Polymorphism Detection

A new strategy of simple, inexpensive, rapid, and label-free single-nucleotide-polymorphism (SNP) detection using robust chemosensors with piezomicrogravimetric, surface plasmon resonance, or capacitive impedimetry (CI) signal transduction is reported. Using these chemosensors, selective detection of a genetically relevant oligonucleotide under FIA conditions within 2 min is accomplished. An invulnerable-to-nonspecific interaction molecularly imprinted polymer (MIP) with electrochemically synthesized probes of hexameric 2,2'-bithien-5-yl DNA analogues discriminating single purine-nucleobase mismatch at room temperature was used. With density functional theory modeling, the synthetic procedures developed, and isothermal titration calorimetry quantification, adenine (A)- or thymine (T)-substituted 2,2'-bithien-5-yl functional monomers capable of Watson-Crick nucleobase pairing with the TATAAA oligodeoxyribonucleotide template or its peptide nucleic acid (PNA) analogue were designed. Characterized by spectroscopic techniques, molecular cavities exposed the ordered nucleobases on the 2,2'-bithien-5-yl polymeric backbone of the TTTATA hexamer probe designed to hybridize the complementary TATAAA template. In that way, an artificial TATAAA-promoter sequence was formed in the MIP. The purine nucleobases of this sequence are known to be recognized by RNA polymerase to initiate the transcription in eukaryotes. The hexamer strongly hybridized TATAAA with the complex stability constant K_s^{TTTATA-TATAAA} = k_a/k_d ≈ 10⁶ M^-1, as high as that characteristic for longer-chain DNA-PNA hybrids. The CI chemosensor revealed a 5 nM limit of detection, quite appreciable as for the hexadeoxyribonucleotide. Molecular imprinting increased the chemosensor sensitivity to the TATAAA analyte by over 4 times compared to that of the nonimprinted polymer. The herein-devised detection platform enabled the generation of a library of hexamer probes for typing the majority of SNP probes as well as studying a molecular mechanism of the complex transcription machinery, physics of single polymer molecules, and stable genetic nanomaterials.

Preparation of protein imprinted polymers via protein-catalyzed eATRP on 3D gold nanodendrites and their application in biosensors

Sensitive detection of metalloproteins is very essential in human pathologies.

Molecularly imprinted polymers on graphene oxide surface for EIS sensing of testosterone

A novel electrochemical biosensor was developed for ultrasensitive determination of testosterone from femtomolar to micromolar levels via electrochemical impedance spectroscopy (EIS) measurements. The sensor features a nanosized molecularly imprinted polymer (MIP) film that was electrochemically grafted on a graphene-oxide sheets modified electrode. The detection mechanism of this senor is explained via the change of the interfacial impedance that derived from the recognition of the target molecule. Due to the nanosheet structure as well as the high surface area of graphene-oxide, the sensitivity of the MIP sensor is enhanced remarkably. Under an optimized condition, a wide linear range from 1fM to 1µm (1×10^-15-1×10^-6molL^-1) and a detection limit of 0.4fM (4.0×10^-16molL^-1) was obtained. This composite film presented a good selectivity over structurally similar steroid hormones, and a long term stability in room temperature for the detection of testosterone. Considering these advantages, the MIP/GO electrochemical biosensor could be a substitute of testosterone immunosensor, and may be further extended to the detection of other endogenous substances.

Molecularly imprinted polymer membranes and thin films for the separation and sensing of biomacromolecules

This review describes recent advances associated with the development of surface imprinting methods for the synthesis of polymeric membranes and thin films, which possess the capability to selectively and specifically recognize biomacromolecules, such as proteins and single- and double-stranded DNA, employing "epitope" or "whole molecule" approaches. Synthetic procedures to create different molecularly imprinted polymer membranes or thin films are discussed, including grafting/in situ polymerization, drop-, dip-, or spin-coating procedures, electropolymerization as well as micro-contact or stamp lithography imprinting methods. Highly sensitive techniques for surface characterization and analyte detection are described, encompassing luminescence and fluorescence spectroscopy, X-ray photoelectron spectroscopy, FTIR spectroscopy, surface-enhanced Raman spectroscopy, atomic force microscopy, quartz crystal microbalance analysis, cyclic voltammetry, and surface plasmon resonance. These developments are providing new avenues to produce bioelectronic sensors and new ways to explore through advanced separation science procedures complex phenomena associated with the origins of biorecognition in nature.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

A potential-gated molecularly imprinted smart electrode for nicotinamide analysis

Triggered surface responsiveness paves the way for smart sensor technologies that not only have tunable retention, but also provide sensing through a ‘built-in’ programming of electrode material.

Electrochemical evaluation of troponin T imprinted polymer receptor

The selective detection and quantification of macromolecular targets is a fundamental biological mechanism in nature. Molecularly imprinted polymers (MIPs) have been identified as one of the most promising synthetic alternatives to bioreceptors. However, expanding this methodology towards selective recognition of bulky templates such as proteins appears to be extremely challenging due to problems associated with removal of the template from the polymeric network. In this study, polymer imprinted with troponin T (TnT) was assessed using electrochemical methods and the influence of various extraction methods, including conventional immersion extraction, thermal annealing and ultrasonic-assisted extraction, on the binding characteristics of the troponin-to-imprinted polymer receptor was elucidated. Cyclic voltammetric deposition of o-phenylenediamine (o-PD) film in the presence of TnT as a template was performed in acetate buffer (0.5 M, pH 5.2) on a gold substrate. Solvent extraction of the target molecule was optimised and followed by subsequent washing with water. The electrochemistry of a ferro/ferricyanide probe was used to characterise the TnT MIP receptor film. The incubation of the TnT MIP receptor-modified electrode with respect to TnT concentration resulted in a suppression of the ferro/ferricyanide redox current. The dissociation constant (KD) was calculated using a two-site model of template affinity for the TnT MIP receptor. The synthetic TnT MIP receptor had high affinity for TnT with a KD of 2.3×10(-13) M.

Biosensors: sense and sensibility

This review is based on the Theophilus Redwood Medal and Award lectures, delivered to Royal Society of Chemistry meetings in the UK and Ireland in 2012, and presents a personal overview of the field of biosensors. The biosensors industry is now worth billions of United States dollars, the topic attracts the attention of national initiatives across the world and tens of thousands of papers have been published in the area. This plethora of information is condensed into a concise account of the key achievements to date. The reasons for success are examined, some of the more exciting emerging technologies are highlighted and the author speculates on the importance of biosensors as a ubiquitous technology of the future for health and the maintenance of wellbeing.

Novel electrochemical biosensor based on functional composite nanofibers for sensitive detection of p53 tumor suppressor gene

A novel electrochemical biosensor based on functional composite nanofibers for sensitive hybridization detection of p53 tumor suppressor using methylene blue (MB) as an electrochemical indicator is developed. The carboxylated multi-walled carbon nanotubes (MWNTs) doped nylon 6 (PA6) composite nanofibers (MWNTs-PA6) was prepared using electrospinning, which served as the nanosized backbone for pyrrole (Py) electropolymerization. The functional composite nanofibers (MWNTs-PA6-PPy) used as supporting scaffolds for ssDNA immobilization can dramatically increase the amount of DNA attachment and the hybridization sensitivity. The biosensor displayed good sensitivity and specificity. The target wild type p53 sequence (wtp53) can be detected as low as 50 fM and the discrimination is up to 57.5% between the wtp53 and the mutant type p53 sequence (mtp53). It holds promise for the early diagnosis of cancer development and monitoring of patient therapy.