QCM-D Analysis of the Performance of Blocking Agents on Gold and Polystyrene Surfaces

Abstract

With today's developments of biosensors and medical implants comes the need for efficient reduction of nonspecific binding. We report on a comparison of the ability of traditionally used blocking agents and poly(ethylene glycol) (PEG) derivatives to prevent protein adsorption on both gold and polystyrene surfaces. The adsorption kinetics of blocking molecules and proteins was monitored gravimetrically using quartz crystal microbalance with dissipation (QCM-D). The resistance to nonspecific adsorption was evaluated on gold and polystyrene surfaces coated with bovine serum albumin (BSA) or casein, gold coated with three different 6-11 ethylene glycol (EG) long hydroxyl- or methoxy-terminated PEG-thiolates and polystyrene blocked with a PLL-g-PEG or three different 12 EG long benzyl-PEG-derivatives. The prevention of protein adsorption on the coated surfaces was evaluated by monitoring the mass uptake at the addition of both pure prostate specific antigen (PSA) and seminal plasma. We demonstrate that on pure gold the PEG-thiols are superior to the other blocking molecules tested, with the end group and length of the PEG-thiols used being of minor importance. On polystyrene surfaces blocking with PLL-g-PEG, BSA and casein gave the best results. These results have an impact on further development of an optimized immunoassay protocol.

Simple Coatings to Render Polystyrene Protein Resistant

“…This translates to 478.3 ng/cm 2 ± 8.7 ng/cm 2 BSA adsorbed, in good agreement with literature [21].…”

Albumin adsorption on unmodified and sulfonated polystyrene surfaces, in relation to cell–substratum adhesion

“…The prevention from any nonspecific protein binding is important in the immunoassay clinical diagnosis and in the preparation of immobilized enzymes by adsorption methods [4,34]. The sensitivity of such assays depends on biochemical parameters, such as the signal-to-background ratio, and on the nonspecific binding of label molecules.…”

Block copolymers for the rational design of self-forming postsurgical adhesion barriers

“…(1)), where C is a constant characteristic of the system (17.7 ng cm À2 Hz), and n is the number of the harmonic overtone being considered [42]. Since the change in energy dissipation was small in all measurements (<1 Â 10 À6 per 10 Hz frequency change), the Sauerbrey model was assumed to provide an accurate description of the adsorbed mass for all analyses with the usual caveat that the QCM measurement also includes any water bound or coupled to the surface [43]. A representative curve of specific mass adsorption is shown in Fig.…”