Design Strategies of Fluorescent Biosensors Based on Biological Macromolecular Receptors

Fluorescent biosensors to detect the bona fide events of biologically important molecules in living cells are increasingly demanded in the field of molecular cell biology. Recent advances in the development of fluorescent biosensors have made an outstanding contribution to elucidating not only the roles of individual biomolecules, but also the dynamic intracellular relationships between these molecules. However, rational design strategies of fluorescent biosensors are not as mature as they look. An insatiable request for the establishment of a more universal and versatile strategy continues to provide an attractive alternative, so-called modular strategy, which permits facile preparation of biosensors with tailored characteristics by a simple combination of a receptor and a signal transducer. This review describes an overview of the progress in design strategies of fluorescent biosensors, such as auto-fluorescent protein-based biosensors, protein-based biosensors covalently modified with synthetic fluorophores, and signaling aptamers, and highlights the insight into how a given receptor is converted to a fluorescent biosensor. Furthermore, we will demonstrate a significance of the modular strategy for the sensor design

Developments in nanoparticles for use in biosensors to assess food safety and quality

The following will provide an overview on how advances in nanoparticle technology have contributed towards developing biosensors to screen for safety and quality markers associated with foods. The novel properties of nanoparticles will be described and how such characteristics have been exploited in sensor design will be provided. All the biosensor formats were initially developed for the health care sector to meet the demand for point-of-care diagnostics. As a consequence, research has been directed towards miniaturization thereby reducing the sample volume to nanolitres. However, the needs of the food sector are very different which may ultimately limit commercial application of nanoparticle based nanosensors. © 2014 Elsevier Ltd

MIPs and Aptamers for Recognition of Proteins in Biomimetic Sensing

Biomimetic binders and catalysts have been generated in order to substitute the biological pendants in separation techniques and bioanalysis. The two major approaches use either “evolution in the test tube” of nucleotides for the preparation of aptamers or total chemical synthesis for molecularly imprinted polymers (MIPs). The reproducible production of aptamers is a clear advantage, whilst the preparation of MIPs typically leads to a population of polymers with different binding sites. The realization of binding sites in the total bulk of the MIPs results in a higher binding capacity, however, on the expense of the accessibility and exchange rate. Furthermore, the readout of the bound analyte is easier for aptamers since the integration of signal generating labels is well established. On the other hand, the overall negative charge of the nucleotides makes aptamers prone to non-specific adsorption of positively charged constituents of the sample and the “biological” degradation of non-modified aptamers and ionic strength-dependent changes of conformation may be challenging in some application

Bio-imprinted hydro-gels (BIGS) for protein and virus detection

Detection of bio-markers at low concentration is becoming a more and more important topic in scientific research due to its importance in applications crucially related to people’s life like medical diagnosis, environment protection and national security. In the past decades, as the improvement of the modern analytical technologies progressed, plenty of methodologies have been developed to realize the fast and accurate detection of bio-markers in liquid media. However, some drawbacks still remain like the expensive cost, high requirement of operational environment, and need for skilled operators. Here, a new kind of aptamer-based bio-imprinted hydrogel sensor (BIG) with specific macroscopic volume response to certain biomarkers like proteins and virus at low concentration is reported. These super-aptamer hydrogels exhibit macroscopic volume change that can be detected by naked eyes when being treated with bio-marker solutions at extremely low concentration. This extraordinary macromolecular amplification is attributed to a complex interplay between biomarker-aptamer crosslinks and the structure of the hydrogel network surrounding it. Additionally, based on the work mentioned above, a new kind of bio-imprinted grating hydrogel film which can show visible change of the laser diffraction pattern when treated with biomarker solutions was also designed and fabricated based on the super-aptamer bioimprinted hydrogels. These films have also been proved to be able to detect both proteins and virus at low concentration in solutions

Molecular Imprinting of Peptides and Proteins

Molecular imprinting described as a method utilized to create artificial receptors and antibodies by construction of selective recognition sites in a synthetic polymer can be a promising tool for generating peptide and protein artificial specific recognition sites. These materials, as potential antibody substitutes, have attracted great interest and attention in different fields such as peptide and protein purification and separation, chemical/electrochemical/optical sensors/biosensors, chromatographic stationary phases, and enzyme mimics. This review has focused on fundamentals of molecularly imprinted polymers in terms of selection of molecular template, functional monomer, cross linker, and polymerization format. Furthermore, several applications of peptide/protein-imprinted materials are highlighted and challenges regarding the intrinsic properties of peptide/ protein imprinting have been emphasized.HighlightsHighlights the fundamentals of peptides and proteins molecular imprinting.Summarizes the essential elements and polymer formats of peptide/protein imprinted materials.Highlights the applications of peptide/protein imprinting.Highlights the challenges in peptide/protein imprinting

Molecularly Imprinted Polymers (PIMs) in Biomedical Applications

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Molecularly imprinted polymers with assistant recognition biomolecule for protein detection

Molecularly imprinted polymers are ideal alternatives to natural recognition elements for a variety of reasons, including facile synthesis, greater chemical and long term stability, and reusability. One of the most challenging tasks in developing such polymers is provide them of a signal transduction capability, enabling to respond to a specific binding event. In this thesis, protein-imprinted polymers, capable of specific transduction of binding event into a fluorescence change were prepared using an assistant-peptide bearing an environment-sensitive fluorophore. The preparation has included the synthesis of the environment-sensitive peptide and subsequent incorporation into the polymer network through the imprinting process. Binding studies proved that MIP-SA-allyl-peptide has large absorption capacity and good affinity and selectivity toward BSA when compared with pure MIP. The greater binding properties of MIP-SA-allyl-peptide were found to derive from the assistant-peptide that suitably oriented into the cavity, acts as binding site in cooperation with the imprinted cavity. Furthermore, transduction signaling studies proved that MIP-SA-allyl-dansyl-peptide is able to detect and report the protein binding into a precise detection range. The proposed fluorescent-imprinted polymer provides a new and general strategy for protein-sensing platforms and opens up to the field of biosensors

Polydiacetylene Biosensors in Food Microbiology Applications

Polydiacetylenes (PDAs) are conjugated polymers which consist of diacetylene monomers (DAs). DAs are colorless and can be polymerized under UV light at 254nm to form blue PDAs. Stimuli such as heat, chemicals, mechanic force and pH change will trigger color change of PDA from blue to red/pink. This chroma property makes PDA an ideal material for sensor development and therefore has received considerable attention in recent years. There has been several reports of generating PDA-based sensors for cations, chemicals, virus, microorganisms, and bacterial toxins detection. However, development of PDA-based sensors for food microbiology applications were limited. The objective of this study were thus to 1) investigate the sanitizers and surfactant effect on PDA-based sensors 2) develop a PDA-based biosensor for bacteria detection and verify the working mechanism 3) optimize and apply PDA-based biosensor for bacteria detection. 4) build and validate the statistical model for quantitative bacteria in samples. We started with generating liquid state PDA-based sensors and explored interaction between sanitizers/surfactant and PDA-based sensors. Subsequently, solid state PDA-based sensors were developed and detection mechanism for this method was verified with specifically designed experiments. Further, solid state PDA-based sensors were optimized and applied for bacteria detection with a statistical model built for quantitative bacteria in samples. This study provide a novel strategy of applying PDA-based biosensors for bacteria detection with quantitative measurement of bacteria and was supported by verified detection mechanism. Furthermore, this proposed method can be applied to quickly detect and quantify bacteria and may inspire other PDA-based biosensor design in the future