In vitro selection of electrochemical peptide probes using bioorthogonal tRNA for influenza virus detection

In Vitro Selection of Collagen-Binding Vascular Endothelial Growth Factor Containing Genetically Encoded Mussel-Inspired Adhesive Amino Acids

Protein immobilization technology is important in medical and industrial applications. We previously reported all-in-one in vitro selection, wherein a collagen-binding vascular endothelial growth factor (CB-VEGF) was identified from a fusion library of random and VEGF sequences. However, its interaction chemistry is mainly limited to the interaction established by the 20 canonical amino acids. Herein, we incorporated an adhesive non-natural amino acid found in marine mussels, L-3,4-dihydroxyphenylalanine (DOPA), into the library for all-in-one in vitro selection. After selection, we identified DOPA-containing CB-VEGF. CB-VEGF binds to collagen with an apparent dissociation constant of 2 nM; naïve VEGF does not bind to collagen. The collagen-binding peptide domain of CB-VEGF (CB-peptide) exhibited stronger binding to collagen than a mutant peptide (substitution from DOPA to tyrosine), indicating the importance of DOPA to collagen binding. The collagen-binding affinity of CB-VEGF is 10-fold higher than that of CB-peptide, suggesting that the collagen-binding ability of CB-VEGF is not due to the additive function of CB-peptide to VEGF, but is synergistic. Furthermore, increased cell growth was observed on CB-VEGF-treated collagen surfaces, not VEGF-treated collagen surfaces. Thus, integrating all-in-one in vitro selection and DOPA incorporation shows promise in generating adhesive proteins on solid supports.

Chelation-Induced Zwitterion-like Antifouling Behavior on Anionic Poly(3,4-ethylenedioxythiophene) Surfaces

Antifouling properties are crucial for enhancing the longevity and functionality of biomedical implants, drug delivery systems, and biosensors. Zwitterionic polymers are renowned for their exceptional surface hydration and charge neutrality, which effectively resist biomolecular adsorption and protein attachment. We propose an innovative approach to develop zwitterion-like antifouling surfaces by chelating divalent cations with anionic poly(3,4-ethylenedioxythiophene) (PEDOT) films, specifically PEDOT-PO4 and PEDOT-COOH. The chelation behavior of these films was systematically evaluated using Na+, Mg2+, and Ca2+ ions. Divalent ions, particularly Ca2+ and Mg2+, exhibit a strong affinity for the anionic groups, leading to significant antifouling properties. These modified surfaces effectively repelled both negatively charged bovine serum albumin (BSA) and positively charged lysozyme (LYZ) proteins across various pH environments. This study offers valuable insights into the antifouling characteristics of charged surfaces, enhancing our understanding of how ion-mediated surface modifications influence protein adsorption and interactions.

Recent advances in PEDOT/PProDOT-derived nano biosensors: engineering nano assemblies for fostering advanced detection platforms for biomolecule detection

With the recent unprecedented emergence of a global pandemic, unknown diseases and new metabolic patterns expressing serious health issues, the requirement to develop new diagnostic tools, therapeutic solutions, and healthcare and environmental monitoring systems are significantly higher in the present situation. Considering that high sensitivity, selectivity, stability and a low limit of detection (LOD) are inevitable requirements for an ideal biosensor, the class of conducting polymers of poly(3,4-ethylenedioxythiophene) (PEDOT) and recently poly(3,4-propylenedioxythiophene) (PProDOT) materials have been demonstrated to be promising candidates for designing sensor devices. Nanostructure engineering of these polymeric materials with tunable surface properties and side chain functionalization to enable sensor probe conjugation combined with signal amplification devices such as OECTs and OFETs can fulfil the requirements of next-generation smart nano-biosensors. In this review, we analyze recent reports on PEDOT/PProDOT nanostructures and nanocomposites for developing nano-biosensors and their application in the detection of different biomarkers, environmental, toxicology, marine and aquatic monitoring, forensic and illicit drug detection, etc. In addition, we discuss the challenges associated with the design of PEDOT/PProDOT nano-biosensors and future perspectives on the exploration of novel sensor platforms, particularly PProDOT derivatives for bioelectronics and novel design strategies for next-generation smart nano-biosensors.

Advancements in electrochemical biosensing for respiratory virus detection: A review

Respiratory viruses are real menace for human health which result in devastating epidemic disease. Consequently, it is in urgent need of identifying and quantifying virus with a rapid, sensitive and precise approach. The study of electrochemical biosensors for respiratory virus detection has become one of the most rapidly developing scientific fields. Recent developments in electrochemical biosensors concerning respiratory virus detection are comprehensively reviewed in this paper. This review is structured along common detecting objects of respiratory viruses, electrochemical biosensors, electrochemical biosensors for respiratory virus detection and future challenges. The electrochemical biosensors for respiratory virus detection are introduced, including nucleic acids-based, immunosensors and other affinity biosensors. Lastly, for Coronavirus disease 2019 (COVID-19) diagnosis, the future challenges regarding developing electrochemical biosensor-based Point-of-Care Tests (POCTs) are summarized. This review is expected to provide a helpful guide for the researchers entering this interdisciplinary field and developing more novel electrochemical biosensors for respiratory virus detection.

Peptide-Based Photocathodic Biosensors: Integrating a Recognition Peptide with an Antifouling Peptide

Accurate and sensitive detection of targets in practical biological matrixes such as blood, plasma, serum, or tissue fluid is a frontier issue for most biosensors since the coexistence of both potential reducing agents and protein molecules has the possibility of causing signal interference. Herein, aiming at detection in a complex environment, an advanced and robust peptide-based photocathodic biosensor, which integrated a recognition peptide with an antifouling peptide in one probe electrode, was first proposed. Selecting human chorionic gonadotropin (hCG) as a model target, the recognition peptide with the sequence PPLRINRHILTR was first anchored on the CuBi₂O₄/Au (CBO/Au) photocathode and then the antifouling peptide with the sequence EKEKEKEPPPPC was further anchored to generate an antifouling biointerface. The peptide-based photocathodic biosensor demonstrated excellent anti-interference to both nonspecific proteins and reducing agents because of the capability of the antifouling peptide. It also exhibited good sensitivity owing to the utilization of the recognition peptide rather than an antibody probe. This peptide-integrated method offers a new perspective for practical applications of photocathodic biosensors.

Expanding the Chemical Diversity of Genetically Encoded Libraries

The power of ribosomes has increasingly been harnessed for the synthesis and selection of molecular libraries. Technologies, such as phage display, yeast display, and mRNA display, effectively couple genotype to phenotype for the molecular evolution of high affinity epitopes for many therapeutic targets. Genetic code expansion is central to the success of these technologies, allowing researchers to surpass the intrinsic capabilities of the ribosome and access new, genetically encoded materials for these selections. Here, we review techniques for the chemical expansion of genetically encoded libraries, their abilities and limits, and opportunities for further development. Importantly, we also discuss methods and metrics used to assess the efficiency of modification and library diversity with these new techniques.

Thiophene-Based Aldehyde Derivatives for Functionalizable and Adhesive Semiconducting Polymers

The pursuit for novelty in the field of (bio)electronics demands for new and better-performing (semi)conductive materials. Since the discovery of poly(3,4-ethylenedioxythiophene) (PEDOT), the ubiquitous golden standard, many studies have focused on its applications but only few on its structural modification and/or functionalization. This lack of structural variety strongly limits the versatility of PEDOT, thus hampering the development of novel PEDOT-based materials. In this paper, we present a short and simple strategy for introducing an aldehyde functionality in thiophene-based semiconducting polymers. First, through a two-step synthesis, an EDOT-aldehyde derivative was prepared and polymerized, both chemically and electrochemically. Next, to overcome the inability of thiophene-aldehyde to be polymerized by any means, we synthesized a trimer in which thiophene-aldehyde is enclosed between two EDOT groups. The successful chemical and electrochemical polymerization of this new trimer is presented. The polymer suspensions were characterized by ultraviolet-visible-near-infrared spectroscopy, while the corresponding films were characterized by Fourier transform infrared and four-point-probe conductivity measurements. Afterward, insoluble semiconducting films were formed by using ethylenediamine as a cross-linker, demonstrating in this way the suitability of the aldehyde group for the easy chemical modification of our material. The efficient reactivity conferred by aldehyde groups was also exploited for grafting fluorescent polyamine nanoparticles on the film surface, creating a fluorescent semiconducting polymer film. The films prepared by electropolymerization, as shown by means of a sonication test, exhibit strong surface adhesion on pristine indium tin oxide (ITO). This property paves the way for the application of these polymers as conductive electrodes for interfacing with living organisms. Thanks to the high reactivity of the aldehyde group, the aldehyde-bearing thiophene-based polymers prepared herein are extremely valuable for numerous applications requiring the facile incorporation of a functional group on thiophene, such as the functionalization with labile molecules (thermo-, photo-, and electro-labile, pH sensitive, etc.).

Detecting and Predicting Emerging Disease in Poultry With the Implementation of New Technologies and Big Data: A Focus on Avian Influenza Virus

Future demands for food will place agricultural systems under pressure to increase production. Poultry is accepted as a good source of protein and the poultry industry will be forced to intensify production in many countries, leading to greater numbers of farms that house birds at elevated densities. Increasing farmed poultry can facilitate enhanced transmission of infectious pathogens among birds, such as avian influenza virus among others, which have the potential to induce widespread mortality in poultry and cause considerable economic losses. Additionally, the capability of some emerging poultry pathogens to cause zoonotic human infection will be increased as greater numbers of poultry operations could increase human contact with poultry pathogens. In order to combat the increased risk of spread of infectious disease in poultry due to intensified systems of production, rapid detection and diagnosis is paramount. In this review, multiple technologies that can facilitate accurate and rapid detection and diagnosis of poultry diseases are highlighted from the literature, with a focus on technologies developed specifically for avian influenza virus diagnosis. Rapid detection and diagnostic technologies allow for responses to be made sooner when disease is detected, decreasing further bird transmission and associated costs. Additionally, systems of rapid disease detection produce data that can be utilized in decision support systems that can predict when and where disease is likely to emerge in poultry. Other sources of data can be included in predictive models, and in this review two highly relevant sources, internet based-data and environmental data, are discussed. Additionally, big data and big data analytics, which will be required in order to integrate voluminous and variable data into predictive models that function in near real-time are also highlighted. Implementing new technologies in the commercial setting will be faced with many challenges, as will designing and operating predictive models for poultry disease emergence. The associated challenges are summarized in this review. Intensified systems of poultry production will require new technologies for detection and diagnosis of infectious disease. This review sets out to summarize them, while providing advantages and limitations of different types of technologies being researched.

Thiophene-Conjugated Ligand Probe for Nonenzymatic Turn-On Electrochemical Protein Detection

A new type of turn-on electrochemical protein detection is developed using an electropolymerizable molecular probe. To detect trypsin, a benzamidine ligand is conjugated with a thiophene moiety. Encapsulation of the probe in the trypsin pocket prevents electropolymerization, leading to efficient electron transfer from the electrolyte to the electrode. In contrast, unbound probes can become electropolymerized, yielding a polythiophene layer on the electrode. The polythiophene formed this way suppressed electron transfer. The detection limit of trypsin using this electrochemical strategy is 50 nM. The method is shown to be useful for nonenzymatic turn-on electrochemical detection.

Approaching single DNA molecule detection with an ultrasensitive electrochemical genosensor based on gold nanoparticles and cobalt-porphyrin DNA conjugates

An ultrasensitive genosensor is obtained by using gold nanoparticles and cobalt-porphyrin labelled DNA reporter strands with an attomolar detection limit.