Novel Biosensing Technology Based On Nanomaterials

Nanomaterials because of its unique volume effect, quantum size, excellent surface effect and unique optical speciality, huge changes have taken place in its electrical, mechanical, optics ,magnetics and other aspects . They have received much attention for their potential wide applications in the field of chemical,food,biological medicine,environment monitoring, medicine and military. Nanotechnology offers unique opportunities for creating highly sensitive innovative biosensing devices and ultrasensitive bioassays. Biological chemistry as one of the most promising field of application, research about it has become the hotspot. This assay use carbon nanotubes and gold nanoparticles (GNPs) two common nanomaterials, building a new method of analysis or establish a new type of sensor. The details are summarized as follows:(1)Carbon nanotubes (CNTs) as ideal one-dimensional nanomaterial have valuable applications in chemical biosensors due to large aspect ratio, excellent electrical conductivity special biological affinity and high electrocatalytic activity. Taking advantage of the fluorescence quenching ability of single wall carbon nanotubes (SWCNT), terminal protection of small-molecule-linked DNA via selective carbon nanotube assembly has been constructed. The small-molecule-linked ssDNA will be hydrolyzed successively into mononucleotides from the 3′end by Exo I. When ssDNA is bound to the protein target (streptavidin, SA) through the small-molecule(biotin,BT) moiety, Exo I fails to catalyze the stepwise hydrolysis of the small-molecule-linked DNA, leaving the ssDNA intact. This terminal protection, in contrast to those mediated by the interaction of proteins with specific DNA sequences is sequence-independent with no interaction between DNA and proteins, because it merely involves the binding of the small molecule moiety to its protein target. So this terminal protection is expected to establish a platform for the interaction of small molecule and protein.(in chapter 2)(2)Immobilization of biomolecules with GNPs plays an important role in the construction of biosensors. Due to their large specific surface area and high surface free energy, easy conjugation chemistry, good conductivity and biocompatibility, using GNPs as substrates for biomolecule immobilization can effectively retain the activity of biomolecules, enhance immobilization results, improve the stability of biosensors and facilitate the electron transfer efficiency. Furthermore, enormous signal amplification can also be achieved by linking the biorecognition unit to nanoparticle carrying multiple signal tracers. In this work, we use GNPs as SERS active surface, present the study of SERS detection of MDA, which is also based on the TBA/MDA addition reaction. Compared traditional fluorescence and UV–visible (UV–vis) spectro-photometric methods, the main focus of this study is to explore the TBA–MDA SERS sensitivity as well as its molecular specificity. Our results demonstrated that our sensor has a favorable linear relationship toward MDA range from 100μM to 100 nM. (in chapter 3)...