Development of Non-Labeled QCM Biosensor for the Detection of <i>β</i>-Galactosidase: A Comparative Study of Gold and Polystyrene Nanoparticles

Abstract

The performance of gold and polystyrene nanoparticles was investigated using quartz crystal microbalance (QCM) as sensor platform; β-Galactosidase antibody with corresponding antigen was utilized for the immunoreaction. The development of the immunosensor included: 1) formation of self assembled monolayers on quartz crystals; 2a) immobilization of p-aminothiophenol functionalized gold nanoparticles on carboxyl-terminated self assembled monolayer, or 2b) immobilization of polystyrene nanoparticles on crystals modified with p-aminothiophenol self assembled monolayer; 3) attachment of monoclonal anti β-Gal on nanoparticles; and 4) detection of target analyte. The nanoparticles used were synthesized in house and characterized by transmission electron microscopy and infrared spectroscopy. The results revealed that antibodies were strongly attached to functionalized gold nanoparticles; the weaker immobilization of antibodies to polystyrene nanoparticles provoked their detachment during antigen detection. When cross reactivity of polystyrene nanoparticles was checked using a different antigen (Brucella), displacement of antibody was not recorded, demonstrating specificity of the reaction. To the best of our knowledge this is the first direct comparison between behaviors of biosensors developed with two commonly used nanoparticles. The results showed that both nanoparticles produced biosensors capable to detect β-Gal. Nevertheless biosensors developed using polystyrene nanoparticles are simpler, cheaper and more eco-friendly than those developed using gold nanoparticles.

Interrelation of Elasticity, Isotherm of Adsorbed Proteins, and its Subsequent Displacement by a Surfactant

“…35,36 The analysis of adsorption isotherms of BSA on APDMES and PTMS surfaces indicates adsorbed mass of BSA on the hydrophilic amine surface is 4.6 mg/m 2 at C g = 0.1 mg/mL and 5 mg/m 2 at C g = 1 mg/mL, and on the hydrophobic methyl surface, the adsorbed mass varied from 5.3 to 5.9 mg/m 2 depending on the C g values from 0.1 to 1 mg/mL. The values are very close to the reported 37,38 values. The K s values indicate that the adsorption strength of BSA is marginally higher on the PTMS surface.…”

Facile Synthesis of Fluorescent Latex Nanoparticles with Selective Binding Properties Using Amphiphilic Glycosylated Polypeptide Surfactants

“…This involves the conjugation of targeting ligands to the exposed surface of NPs, which interact with receptors expressed on the targeted cells. Targeting ligands which have been successfully utilized thus far include antibodies, peptides, aptamers, and carbohydrates (glycans). − The latter has come to the forefront of the scientific community in the past number of years with the discovery that glycans regulate numerous biological processes such as cell communication and selective binding of other biological species, among others, which makes glycochemistry an attractive tool in the design of materials for selective targeting. − In particular, complex (surface) glycoproteins are involved in biological binding events, and this has inspired research into the development of simplistic synthetic glycoprotein mimics. − Of particular attraction are glycopolypeptides derived from the polymerization of amino acid N -carboxyanhydrides (NCA) due to their ready availability and structural similarity to natural proteins. − The successful formulation of these glycopolypeptides into bioactive nanomaterials has been demonstrated albeit mostly by self-assembly. − …”