Analytical applications of biomimetic recognition elements - an update

Breaking barriers in electrochemical biosensing using bioinspired peptide and phage probes

Electrochemical biosensing continues to advance tirelessly, overcoming barriers that have kept it from leaving research laboratories for many years. Among them, its compromised performance in complex biological matrices due to fouling or receptor stability issues, the limitations in determining toxic and small analytes, and its use, conditioned to the commercial availability of commercial receptors and the exploration of natural molecular interactions, deserved to be highlighted. To address these challenges, in addition to the intrinsic properties of electrochemical biosensing, its coupling with biomimetic materials has played a fundamental role, among which bioinspired phage and peptide probes stand out. The versatility in design and employment of these probes has opened an unimaginable plethora of possibilities for electrochemical biosensing, improving their performance far beyond the development of highly sensitive and selective devices. The state of the art offers robust electroanalytical biotools, capable of operating in complex samples and with exciting opportunities to discover and determine targets regardless of their toxicity and size, the commercial availability of bioreceptors, and prior knowledge of molecular interactions. With all this in mind, this review offers a panoramic, novel, and updated vision of both the tremendous advances and opportunities offered by the combination of electrochemical biosensors with bioinspired phage and peptide probes and the challenges and research efforts that are envisioned in the immediate future.

Towards miniaturized electrochemical sensors for monitoring of polychlorinated biphenyls

Pollution of our environment as a result of industrialization and other human activities is a growing concern due to the harmful effects of most chemicals that are released into the environment. Of particular interest are the persistent organic pollutants (POPs) that are reported to be toxic and build up in the environment due to their persistence. Among the POPs are polychlorinated biphenyls (PCBs), which were widely used in the past in various applications ranging from additives in pesticides to dielectric fluids in electrical equipment. As a way of protecting the one health trilogy (environment, human and animal health), their determination in the environment is a paramount call that has seen researchers continue to provide advanced technologies towards achieving this goal. These technologies involve the conventional gold standard gas chromatography systems coupled to sensitive detectors that can detect trace level concentrations. They have come in handy in monitoring of PCBs but their application for routing monitoring may not be sustainable because of the cost of operation associated with them and the need for experts to run the equipment. As a result, there is need for affordable systems that are still able to achieve the required sensitivity for routine monitoring and real-time data acquisition. Sensor systems fit very well in this category since they can be miniaturized for affordability and portray many other desirable features. PCBs as environmentally relevant environmental pollutants have received minimal attention with regards to sensor development and this review highlights the efforts that have been made so far. It provides in-depth discussions on electrochemical sensors and the various modifications that have been employed to date to achieve detection of PCBs at low concentrations as well as the future prospects in remote and routine monitoring.

Advances and perspectives in the analytical technology for small peptide hormones analysis: A glimpse to gonadorelin

In the last twenty years, we have witnessed an important evolution of bioanalytical approaches moving from conventional lab bench instrumentation to simpler, easy-to-use techniques to deliver analytical responses on-site, with reduced analysis times and costs. In this frame, affinity reagents production has also jointly advanced from natural receptors to biomimetic, abiotic receptors, animal-free produced. Among biomimetic ones, aptamers, and molecular imprinted polymers (MIPs) play a leading role. Herein, our motivation is to provide insights into the evolution of conventional and innovative analytical approaches based on chromatography, immunochemistry, and affinity sensing referred to as peptide hormones. Indeed, the analysis of peptide hormones represents a current challenge for biomedical, pharmaceutical, and anti-doping analysis. Specifically, as a paradigmatic example, we report the case of gonadorelin, a neuropeptide that in recent years has drawn a lot of attention as a therapeutic drug misused in doping practices during sports competitions.

Development of aptamers for rapid airborne bacteria detection

Airborne microbes can rapidly spread and cause various infectious diseases worldwide. This necessitates the determination of a fast and highly sensitive detection method. There have been no studies on receptors targeting Citrobacter braakii (C. braakii), a pathogenic bacterium which can exist in the air. In this study, we rapidly isolate an aptamer, a nucleic acid molecule that can specifically bind to C. braakii by centrifugation-based partitioning method (CBPM) reported previously by our groups as omitting the repeated rounds of binding incubation, separation, and amplification that are indispensable for SELEX. The binding affinity and specificity of isolated aptamers are checked using bacteria in liquid culture and recollection solution from aerosolized bacteria. Recollection solutions of the recovered bacteria are obtained by nebulizing, drying, and recapturing with a biosampler. The CB-5 aptamer shows high affinity and specificity for C. braakii (K_d: 16.42 in liquid culture and 26.91 nM in recollection from aerosolized sample). Our results indicate the current protocol can be employed for the rapid development of reliable diagnostic receptors targeting airborne bacteria.

A biomimetic enzyme-linked immunosorbent assay (BELISA) for the analysis of gonadorelin by using molecularly imprinted polymer-coated microplates

An original biomimetic enzyme-linked immunoassay (BELISA) to target the small peptide hormone gonadorelin is presented. This peptide has been recently listed among the substances banned in sports by the World Antidoping Agency (WADA) since its misuse by male athletes triggers testosterone increase. Hence, in response to this emerging issue in anti-doping controls, we proposed BELISA which involves the growth of a polynorepinephrine (PNE)-based molecularly imprinted polymer (MIP) directly on microwells. PNE, a polydopamine (PDA) analog, has recently displayed impressive performances when it was exploited for MIP preparation, giving even better results than PDA. Gonadorelin quantification was accomplished via a colorimetric indirect competitive bioassay involving the competition between biotinylated gonadorelin linked to the signal reporter and the unlabeled analyte. These compete for the same MIP binding sites resulting in an inverse correlation between gonadorelin concentration and the output color signal (λ = 450 nm). A detection limit of 277 pmol L-1 was achieved with very good reproducibility in standard solutions (avCV% = 4.07%) and in urine samples (avCV% = 5.24%). The selectivity of the assay resulted adequate for biological specimens and non-specific control peptides. In addition, the analytical figures of merit were successfully validated by mass spectrometry, the reference anti-doping benchtop platform for the analyte. BELISA was aimed to open real perspectives for PNE-based MIPs as alternatives to antibodies, especially when the target analyte is a poorly or non-immunogenic small molecule, such as gonadorelin. Biomimetic enzyme-linked immunosorbent assay (BELISA).