Biosensor Based On The Assembly Of Gold Nanoparticles For Monitoring The Caspase-3

The self-assembled nanomaterials have great significance in the application of biochemical sensors and biomedical imaging,especially assembly based on noble metal nanoparticles.Noble metal nanoparticles can be fabricated into one-dimensional,two-dimensional and three-dimensional nanostructure by the rational design and control for a variety of applications in biosensing,biological imaging and biotherapy.In this paper,we build a biosensor based on the self-assembly between gold nanorods and gold nanospheres for monitoring the activity of caspase-3.The main contents are as follows:1?Self-assembly of AuNRs and AuNPs.A seed-mediated growth process is employed to prepare AuNRs.Then a small molecule linker with thiol in one end and streptavidin in another end are modified to the surface of AuNRs by the Au-S covalent bond.Similarly,a peptide chain with caspase-3 recognition sequence DEVD is linked to the surface of AuNPs,which possess biotin and thiol at the two ends,respectvely.Finally,the assembly is achieved through the specific recognition between streptavidin and biotin.The assembled nanomaterials have good uniformity and high dispersity by characterization of the TEM and UV-vis spectra.2?Detection of caspase-3 by the self-assembly nanomaterials.The change of signals can be captured by UV-vis spectra,surface plasmon resonance spectra and photoacoustic imaging.Because activated caspase-3 is able to recognize and then cleave the specific sequence DEVD,resulting in the separation of AuNRs and AuNPs.The process causes a blue shift of UV-vis band and the LSPR spectra,in addition,the decrease of the intensity of the photoacoustic imaging.Therefore,the self-assembly nanomaterials are developed for the detection of caspase-3.From the result,the nanosensors have raised promising applications in living thermal therapy and evaluate the therapeutic effect of the anticancer drugs.3?Polarization properties and modification of AuNRs.The polarization propertie of AuNRs are measured by adjusting the angle of light via dark field microscope.Moreover,the bio-modification of AuNRs is explored by using SH-PEG 5000.