Tham khảo tài liệu 'biosensors for health environment and biosecurity part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Label-free Biosensors for Health Applications 167 virus surface antigen reaches 1 ng ml Qi et al. 2009a while the detection sensitivity of CD146 is 1 ng ml see Figure 1 F5 F6 and F7 areas . Fig. 1. Forty-eight protein arrays in a matrix. Left The visual result of a protein micro-array. Right The detailed reactants relative to the left graph Jin 2008 . Automatic control Some parameters of the microfluidic array reactor such as the position number of the sample plate flow velocity in the microfluidic array reactor of sample or ligand time of immobilization or reaction and number of cycles can be edited in the automatic program. Visualization of results Visualized gray-scale images are offered by imaging ellipsometry in several seconds which is shown on a computer screen. The target interacting ligands on the surface can be identified by values in gray-scale with associated software. Quantitative detection Combined with the calibration curve method disease markers and viruses in samples can be detected easily and quantitatively with the label-free biosensor. Operational process of the biosensor based on ellipsometry The operational process of the biosensor which includes surface modification ligand immobilization biomolecule interaction and result reading is shown in Figure 2. Surface modification is a process by which chemical reagents for reactive groups on the silicone surface for biomolecule immobilization Surface modification has two obvious functions one is the presentation of ligand on the biosensing surface and the other is to prevent nonspecific binding Jin 2008 . Presently surface modification methods include physical adsorption chemical covalent immobilization and biologic modification. Physical adsorption is seldom used because the immobilized proteins suffer partial denaturation and tend to leach or wash off of the surface and compete with adsorption Bhatia et al. 1989 . 168 Biosensors for Health Environment and Biosecurity Chemical covalent .
