An electrochemical biosensor for HER2 detection in complex biological media based on two antifouling materials of designed recognizing peptide and PEG

An antifouling electrochemical biosensor using self-signal for Salmonella typhimurium direct detection in food sample

Eating food contaminated by foodborne pathogens can lead to illness. The development of electrochemical sensors for pathogen detection has received widespread attention. However, the analytical performance of electrochemical sensors is inevitably affected by the non-specific adsorption of molecules in the sample. Moreover, the external signal probes might be affected by the complex components in the sample accompanied with signal suppression. This work presents an electrochemical aptasensor for Salmonella typhimurium detection based on the self-signal of poly-xanthurenic acid and the antifouling ability of chondroitin sulfate. The detection time was 60 min. The linear range was from 101 to 107 CFU/mL, and the detection limit was 3 CFU/mL. The biosensors presented good repeatability and storage stability. And the biosensors has been successfully applied in milk and orange juice. This strategy is expected to be applied in the design of other antifouling biosensors, to achieve rapid detection of pathogens and ensure food safety.

Peptide hydrogel based electrochemical biosensor for simultaneous monitoring of H2O2 and NO released from three-dimensional cultured breast cancer cells

An antifouling peptide hydrogel-based electrochemical biosensor was developed for real-time monitoring of hydrogen peroxide (H2O2) and nitric oxide (NO) released by 3D cultured breast cancer cells upon drug stimulation. Platinum nanoparticles (Pt NPs) were electrodeposited on titanium mesh (Pt NPs/TM) to enhance sensitivity and shown to possess excellent electrocatalytic ability toward H2O2 and NO. The composite hydrogel formed by co-assembling of N-fluorenylmethoxycarbonyl diphenylalanine (Fmoc-FF) and a fluorine methoxycarbonyl group-functionalized Lys-(Fmoc)-Asp was coated on Pt NPs/TM electrode surface to provide cellular scaffolding. Their favorable biocompatibility promoted cell adhesion and growth, while good hydrophilicity endowed the sensor with greatly enhanced antifouling capability in complex cell culture environments. The biosensor successfully determined H2O2 and NO secretion from both non-metastatic and metastatic breast cancer cells in real time. Our results demonstrated robust associations between reactive oxygen species (ROS) and reactive nitrogen species (RNS) production and cell malignancy, with the main difference in oxidative stress between the two subtypes of cells being NO release, particularly emphasizing RNS's critical leading in driving cancer metastasis and invasion progression. This sensor holds great potential for cell-release research under the in vivo-like microenvironment and could reveal RNS as an attractive therapeutic target for treating breast cancer.

Progress and Outlook on Electrochemical Sensing of Lung Cancer Biomarkers

Electrochemical biosensors have emerged as powerful tools for the ultrasensitive detection of lung cancer biomarkers like carcinoembryonic antigen (CEA), neuron-specific enolase (NSE), and alpha fetoprotein (AFP). This review comprehensively discusses the progress and potential of nanocomposite-based electrochemical biosensors for early lung cancer diagnosis and prognosis. By integrating nanomaterials like graphene, metal nanoparticles, and conducting polymers, these sensors have achieved clinically relevant detection limits in the fg/mL to pg/mL range. We highlight the key role of nanomaterial functionalization in enhancing sensitivity, specificity, and antifouling properties. This review also examines challenges related to reproducibility and clinical translation, emphasizing the need for standardization of fabrication protocols and robust validation studies. With the rapid growth in understanding lung cancer biomarkers and innovations in sensor design, nanocomposite electrochemical biosensors hold immense potential for point-of-care lung cancer screening and personalized therapy guidance. Realizing this goal will require strategic collaboration among material scientists, engineers, and clinicians to address technical and practical hurdles. Overall, this work provides valuable insight for developing next-generation smart diagnostic devices to combat the high mortality of lung cancer.

Highly efficient GPCR immobilization with enhanced fouling resistance, salt tolerance, and chromatographic performance

The feasibility of immobilized protein-based biodetection relies critically on the activity of the immobilized proteins as well as the biocompatibility of the protein surface. Although many protein immobilization strategies have been developed with satisfied detection readout signals. Non-specific interactions caused by the protein-coating surface are still of great concern since they often interfere with or affect the reliability of detection. Herein, we developed a highly efficient G protein-coupled receptor (GPCR) immobilization method by the combination of polyethylene glycol (PEG) with a self-labeling enzyme-catalyzed reaction. The immobilization relies on the covalent interaction between the fusion tag of a target GPCR (kinase domain of epidermal growth factor receptor, EGFR) and its covalent inhibitor ibrutinib, which is modified on PEGylated silica gels. Two types of GPCRs, N-methyl-D-aspartate 2 A receptor (NMDAR2A) and endothelin A receptor (ETAR), were used as examples to realize protein immobilization. The GPCR modified gels and the affinity columns packed with them have been extensively characterized, in terms of non-specific adsorptions, retention factor (k'), half peak width (W1/2), tailing factor (Tf), theoretical plates (N), and association and dissociation constants of the ligands with the receptors. The immobilized GPCRs with reduced non-specific interactions and enhanced fouling resistance, salt tolerance, and chromatographic performance were clearly observed. We believe it is the first work to introduce PEGylation in GPCR immobilization and provide comprehensive proof-of-concept studies to illustrate the improved antifouling property, salt tolerance, and chromatographic performance. This method could be generally applicable in other immobilized protein-based technology for reliable biodetection.

Antifouling strategies for electrochemical sensing in complex biological media

Surface fouling poses a significant challenge that restricts the analytical performance of electrochemical sensors in both in vitro and in vivo applications. Biofouling resistance is paramount to guarantee the reliable operation of electrochemical sensors in complex biofluids (e.g., blood, serum, and urine). Seeking efficient strategies for surface fouling and establishing highly sensitive sensing platforms for applications in complex media have received increasing attention in the past. In this review, we provide a comprehensive overview of recent research efforts focused on antifouling electrochemical sensors. Initially, we present a detailed illustration of the concept about biofouling along with an exploration of four key antifouling mechanisms. Subsequently, we delve into the commonly employed antifouling strategies in the fabrication of electrochemical sensors. These encompass physical surface topography (micro/nanostructure coatings and filtration membranes) and chemical surface modifications (PEG and its derivatives, zwitterionic polymers, peptides, proteins, and various other antifouling materials). The progress in antifouling electrochemical sensors is proposed concerning the antifouling mechanisms as well as sensing capability assessments (e.g., sensitivity, stability, and practical application ability). Finally, we summarize the evolving trends in the field and highlight some key remaining limitations.

Engineering an Antifouling Electrochemical Sensing Platform Based on an All-in-One Peptide and a Hierarchical β-Bi2O3-Au Microsphere for Vancomycin Detection in Food

Challenges associated with interference aroused by nonspecific attachment of foulants in the food matrix steered the development of sensor surfaces capable of antifouling capacity. In this study, an antifouling electrochemical sensing platform based on an all-in-one peptide (DOPA3-PPPPEKDQDKKaa) with anchoring, antifouling, and recognition functions and a hierarchical β-Bi2O3-Au microsphere was proposed for vancomycin (Van) detection in food. The β-Bi2O3-Au with excellent conductivity was synthesized and introduced as an electrode modifier to accelerate electron transfer on the sensor surface, enhancing sensing response. Mussel organism-inspired oligo DOPA, that is, oligo 3,4-dihydroxyphenylalanine, was employed as the anchoring segment of the all-in-one peptide, which is versatile for surfaces with different materials. PPPPEKDQDK and Kaa as antifouling and recognition segments confer abilities to resist nonspecific adsorption of foulants and specifically bind Van on the sensor surface, respectively. Notably, the excellent antifouling performance of the proposed sensor has been verified in protein solutions, carbohydrate solutions, and even in diluted milk and honey. Molecular dynamics simulation was carried out to explain the antifouling mechanism of the all-in-one peptide. The proposed sensor can detect Van sensitively and selectively with a relatively wide linear range (0.1-100 ng mL-1) and a limit of detection (LOD) as low as 0.038 ng mL-1 and support the quantification of Van in milk, milk powder, and honey samples with satisfactory recoveries within 105.3-110.8%. This antifouling electrochemical sensing platform offers a feasible strategy to reduce matrix interference, which guarantees the accurate detection of Van in food samples.

A multifunctional bio-patch crosslinked with glutaraldehyde for enhanced mechanical performance, anti-coagulation properties, and anti-calcification properties

Bio-patches for the treatment of valvular disease have been evaluated in clinical trials. It has been shown that failure of these devices, occurring within a few years of implantation, may be due to cytotoxicity, immune response, calcification and thrombosis. Some of these effects may be due to the glutaraldehyde crosslinking process used in the preparation of the materials. A number of studies have focused on strategies to control calcification, while others have concentrated on the prevention of micro-thrombus formation. In the present work, we have introduced amino-terminated poly(ethylene glycol) (NH2-PEG-NH2) as an intermolecular bridge, which not only eliminates free aldehyde groups to prevent calcification, but also introduces sites for the attachment of anticoagulant molecules. Furthermore, PEG, itself a hydrophilic polymer with good biocompatibility, may effectively prevent protein adsorption in the early stages of blood contact leading to thrombus formation. After further covalent attachment of heparin, modified bovine pericardium (BP) showed strong anti-calcification (calcium content: 39.3 ± 3.1 μg mg-1) and anti-coagulation properties (partial thromboplastin time: >300 s). The biocompatibility and mechanical properties, important for clinical use, were also improved by modification. The strategy used in this work includes new ideas and technologies for the improvement of valve products used in the clinic.

Ultrasensitive Ratiometric Electrochemiluminescence Sensor with an Efficient Antifouling and Antibacterial Interface of PSBMA@SiO2-MXene for Oxytetracycline Trace Detection in the Marine Environment

The sensitivity and accuracy of electrochemiluminescence (ECL) sensors for detecting small-molecule pollutants in environmental water are affected not only by nonspecific adsorption of proteins and other molecules but also by bacterial interference. Therefore, there is an urgent need to develop an ECL sensor with antifouling and antibacterial functions for water environment monitoring. Herein, a highly efficient antifouling sensing interface (PSBMA@SiO2-MXene) based on zwitterionic sulfobetaine methacrylate (SBMA) antifouling nanospheres (NPs) and two-dimensional MXene nanosheets was designed for the sensitive detection of oxytetracycline (OTC), an antibiotic small-molecule pollutant. Specifically, SBMA with good hydrophilicity and electrical neutrality was connected to SiO2 NPs, thus effectively reducing protein and bacterial adsorption and improving stability. Second, MXene with a high specific surface area was selected as the carrier to load more antifouling NPs, which greatly improves the antifouling performance. Meanwhile, the introduction of MXene also enhances the conductivity of the antifouling interface. In addition, a ratio-based sensing strategy was designed to further improve the detection accuracy and sensitivity of the sensor by utilizing Au@luminol as an internal standard factor. Based on antifouling and antibacterial interfaces, as well as internal standard and ratiometric sensing strategies, the detection range of the proposed sensor was 0.1 ng/mL to 100 μg/mL, with a detection limit of 0.023 ng/mL, achieving trace dynamic monitoring of antibiotics in complex aqueous media.

Optimization of the immunorecognition layer towards Brucella sp. on gold surface for SPR platform

A successful immunosensor is characterized by a proper antibody immobilization and orientation in order to enhance the antigen recognition. In this work, a thorough characterization of the antibody functionalized gold surface is performed to set up the best conditions to implement in an optical platform for the detection of Brucella sp. Two different strategies are evaluated, based on a random immobilization and on an oriented one: a direct antibody immobilization on carboxylic mixed polyethylene (PEG) self-assembled monolayer (SAM) or only carboxylic PEG SAM interface is compared to an oriented immobilization on a layer of protein G on the same PEG SAM interfaces. X-ray Photoelectron Spectroscopy (XPS), Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and contact angle (CA) are used to chemically characterize the gold functionalized surface and ToF-SIMS is also used to confirm the right antibody orientation. Optical characterization is applied to monitor the functionalization steps and fluorescence measurements are used to set up the proper experimental conditions and also to detect Brucella bacteria on the surface. Best results are obtained with a 10 ng/μl incubation solution of antibody immobilized, in an oriented way, on a mixed PEG SAM interface.