Studies On The Interaction Of Protein And Typical Nanomaterials

Nanomaterials are referred as ultrafine materials in nanoscale, which aredifferent from ordinary materials in various properties including optical, electrical,magnetic, thermal, mechanical, and other properties. Nanomaterials also have similarsize as biological macromolecules such as proteins, nucleic acids, etc. Thecombination of both can be assembled to form a new biological nanomaterial forapplications in sensor detection, drug delivery, and medical stents and so on.Therefore nanomaterials have broad prospects of applications in the fields of biologyand medicine. However, the mechanism of interactions between nanomaterials andbiomolecules is not yet study in-depth, which inhibits seriously biologicalapplications of nanomaterial. In this study, the discipline of interactions between theprotein molecules was investigated. Next, three typical nanomaterials (carbonnanotubes, graphene oxide and quantum dots) and protein (or peptides) were selectedto study on the interaction between nanomaterials and biomolecules. Moreover, theproperties of new material (electrochemical, membrane separation, drugtransportation) were researched after the combination of biological macromoleculesand nanomaterials.Firstly, the heat-induced aggregation process of bovine serum albumin (BSA)was investigated at different temperatures. The variations of multi-level structure (2,3,4level) in the protein during the aggregation process were study with variousinstruments of biophysics such as derivative UV absorption, circular dichroism,dynamic light scattering and size exclusion chromatography-multi-angle laser lightscattering. The findings demonstrated that BSA molecules are very stable below60℃,however the BSA experienced a significant thermal aggregation process (hydraulicradius Rhsharp increasing) when the temperature is higher than65℃, whichaccompanied with the unfolding of a large number of secondary structure (thecontent of-helix was reduced with anti-curved shape, transition temperature of67.6℃); the apparent expansion of the tertiary structure (aromatic amino acidsincreased, the transition temperature of65.5℃), the electrostatic shielding (the secondvirial coefficient A2is significantly decreased when the temperature is higher than65℃), and the significant formation of polymer (the molecular weight increases sharply at over65℃).Secondly, amphiphilic peptide derivatives (aspartame) functionalizedmulti-walled carbon nanotube with non-toxic, high biocompatibility were exploited tomodify electrode in order to improve the capabilities of electrochemical sensing.Aspartame is an amphiphilic molecule, which can be adsorbed onto the surface ofcarbon nanotubes via–conjugated non-covalent interactions. Aspartame thus has astrong dispersing ability within a wide pH range, and its dispersion effect is superiorto the traditional dispersant such as SDS. After the dispersion liquid coated on aglassy carbon electrode was evaporated at room temperature, a carbon nanotubemodified layer can be formed effectively at the electrode surface. The results ofmeasurement about hydrogen peroxide illustrated that the composition of aspartameand carbon nanotube improved the detection capabilities of electrode sensor andreduce effectively the detection potential.Thirdly, the graphene oxide as the hydrophilic materials was used to preparedPES hydrophilic ultrafiltration membrane with the function of anti-proteincontamination. The properties and variation in anti-pollution of PES ultrafiltrationmembrane modified with graphene oxide were characterized with various methods.The results indicated that graphene oxide prepared by improved Hummers method canbe uniform and stable in DMF casting solution. Furthermore, graphene oxide can bedispersed uniformly in the PES ultrafiltration membrane by phase inversion, whichcan also significantly improve the hydrophilicity and flux of PES ultrafiltrationmembrane.Finally, the interaction of the two types of polyphenol molecules (Procyanidinand Resveratrol) with BSA were study while three different sizes quantum dotscreated by cadmium telluride (green G-QDs, yellow Y-QDs and red R-QDs) wereinvolved. Findings demonstrated that interactions of polyphenols and BSA weredecreased when quantum dots were added. While G-QDS, Y-QDs and R-QDs wereintroduced, the bonding forces of BSA and Procyanidin were weakened to7.40%,30.62%and8.88%, respectively. Interestingly, the binding forces of BSA withresveratrol were decreased to2.12%,5.61%and0.30%, respectively under G-QDS,Y-QDs, R-QDs participating.