Design of Soft-Interface Materials for Highly Sensitive Bio-Sensing Devices
- PDF / 12,580,957 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 98 Downloads / 165 Views
Design of Soft-Interface Materials for Highly Sensitive Bio-Sensing Devices Madoka Takai Department of Bioengineering, School of Engineering, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 1138656, JAPAN ABSTRACT Two typed bio-conjugated soft-interface for highly sensitive immunoassay was developed by integrating a phospholipid polymer. Nano-sphered surface with poly [2methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)-co-pnitrophenyloxycarbonyl poly(ethylene glycol) methacrylate (MEONP)]: PMBN) was prepared by electrospray deposition (ESD) method. The three dimensional nano-sphered surface can be captured an antibody with high density around 860 ng/cm2. The theoretical amount of closest packed immobilized antibodies on flat surface is around 650 ng/cm2, thus large amount of antibodies were immobilized on the nano-sphere surface. The water stability of PMBN nanostructure was improved by crosslinking with 1,4-butylenediamine and by heating. Both heated and cross-linked PMBN nanostructure was not changed at all remaining high porosity after immersing in water. The specific signal in the immunoassay was enhanced with both heated and cross-linked PMBN nanostructure. The PMBN nanostructure which has high porosity and high water stability realized highly sensitive immunoassay. As the other platform, we developed a novel soft-interface consisting of a well-defined phospholipid polymer surface on which Staphylococcal Protein A (SpA) was site-selectively immobilized. The phospholipid polymer platform was prepared on silicon substrates using the surface-initiated atom transfer radical polymerization (SI-ATRP) technique. Orientationcontrolled antibodies were achieved using enzymatic reactions, and these antibodies captured 1.8 ± 0.1 antigens on average, implying that at least 80% of immobilized antibodies reacted with 2 antigens. Theoretical multivalent binding analysis further revealed that orientation-controlled antibodies had antigen-antibody reaction equilibrium dissociation constants (Kd) as low as 8.6 × 10-10 mol/L, whereas randomly oriented and partially oriented antibodies showed Kd values of 2.0 × 10-7 mol/L and 1.2 × 10-7 mol/L, respectively. These findings support the significance of antibody orientation because controlling the orientation resulted in high reactivity and theoretical binding capacity. INTRODUCTION For further development of sandwich immunoassay system, enhancing the sensitivity has gathered much interest. Vigorous researches have been done in this regard; major examples include approaches to maximize the surface mass density of primary antibodies [1-3], to control the orientation of primary antibodies [4-6], or to maintain the innate biochemical activity of primary antibodies [7]. Regardless of the practical approaches, any platform that aims to enhance the sensitivity faces the two fundamental obstacles: the non-specific protein adsorption and loss of biochemical activities of surface-bound antibodies. Kuwabara et al. tried to compensate the loss of antibody activity by exerting high surface
Data Loading...
