Biofunctionalization of Graphene-Based FET Sensors through Heterobifunctional Nanoscaffolds: Technology Validation toward Rapid COVID-19 Diagnostics and Monitoring
The biofunctionalization of graphene field-effect transistors (GFETs) through vinylsulfonated-polyethyleneimine nanoscaffold is presented for enhanced biosensing of severe acute respiratory-related coronavirus 2 (SARS-CoV-2) spike protein and human ferritin, two targets of great importance for the rapid diagnostic and monitoring of individuals with COVID-19. The heterobifunctional nanoscaffold enables covalent immobilization of binding proteins and antifouling polymers while…
It takes two to tango – The case of thebaine 6-O-demethylase
Thebaine 6-O-demethylase (T6ODM) is an Fe(II)/2-oxoglutarate-dependent dioxygenase catalysing two oxidative O-demethylation reactions in morphine biosynthesis. Its crystal structure revealed a large active site pocket which is at least two times larger than necessary to accommodate a substrate (thebaine or oripavine) molecule. Since so far no crystal structures have been obtained for enzyme-substrate complex, which is necessary…
Surface Preconditioning Influences the Antifouling Capabilities of Zwitterionic and Nonionic Polymer Brushes
Polymer brushes not only represent emerging surface platforms for numerous bioanalytical and biological applications but also create advanced surface-tethered systems to mimic real-life biological processes. In particular, zwitterionic and nonionic polymer brushes have been intensively studied because of their extraordinary resistance to nonspecific adsorption of biomolecules (antifouling characteristics) as well as the ability to be…
Specificity and regenerability of short peptide ligands supported on polymer layers for immunoglobulin G binding and detection
We demonstrate the specificity, regenerability, and excellent storage stability of short peptide-based systems for detection of immunoglobulin G (IgG). The bioactive component consisted of acetylated-HWRGWVA (Ac-HWRGWVA), a peptide with high IgG binding affinity, which was immobilized onto copolymer matrixes of poly(2-aminoethyl methacrylate hydrochloride-co-2-hydroxyethyl methacrylate) (poly(AMA-co-HEMA)). Surface plasmon resonance (SPR) and quartz crystal microgravimetry (QCM) were…
Adhesion and Structural Changes of PEGylated Lipid Nanocarriers on Silica Surfaces
PEGylated lipid nanoparticles have a continuously expanding range of applications, particularly within pharmaceutical areas. Hereby, it is shown with the help of the Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) and other surface sensitive techniques that, at room temperature, PEGylated liposomes and lipodisks adhere strongly to silica surfaces resulting in the displacement of the hydration…
Ultra-low HIV-1 p24 detection limits with a bioelectronic sensor
Early diagnosis of the infection caused by human immunodeficiency virus type-1 (HIV-1) is vital to achieve efficient therapeutic treatment and limit the disease spreading when the viremia is at its highest level. To this end, a point-of-care HIV-1 detection carried out with label-free, low-cost, and ultra-sensitive screening technologies would be of great relevance. Herein, a…
Monitoring biomolecular interaction between folic acid and bovine serum albumin
Folic acid is a bioactive food component whose deficiency can lead to a variety of health problems, while a high intake of folic acid can reduce the cytotoxicity of natural killer cells. The binding mechanism of folic acid to free bovine serum albumin (BSA) was studied using fluorescence, while the biomolecular interaction between confined-BSA and…
Enzyme Multilayers on Graphene-Based FETs for Biosensing Applications
Electrochemical sensors represent a powerful tool for real-time measurement of a variety of analytes of much significance to different areas, ranging from clinical diagnostics to food technology. Point-of-care devices which can be used at patient bedside or for online monitoring of critical parameters are of great importance in clinical daily routine. In this work, portable, low-cost…
Cascading reaction of arginase and urease on a graphene-based FET for ultrasensitive, real-time detection of arginine
Herein, a biosensor based on a reduced graphene oxide field effect transistor (rGO-FET) functionalized with the cascading enzymes arginase and urease was developed for the detection of L-arginine. Arginase and urease were immobilized on the rGO-FET sensing surface via electrostatic layer-by-layer assembly using polyethylenimine (PEI) as cationic building block. The signal transduction mechanism is based on the ability of the cascading enzymes to selectively perform chemical transformations and…
Improved glucose label-free biosensor with layer-by-layer architecture and conducting polymer poly(3,4-ethylenedioxythiophene)
Layer-by-layer (LbL) self-assembly has been used for the development of a new glucose label-free biosensor. Glucose oxidase (GOx) was incorporated in a multilayer film on a gold electrode, previously modified with a film of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT), by electropolymerization, for better conductivity. Multilayer films, containing the enzyme and nitrogen doped graphene (NG) dispersed…