Application Of Nanomaterials In Targeted Drug Delivery And Detection Of Biological Molecules

As one of the major driving forces for nanomaterials, biomedical materials are a very important direction for the development of nanomaterials. Nanomaterials possessed special properties have always been the focus of attention, which provide new modes and approaches for drug delivery and detection of biological molecules. As a new type of nucleic acid probe, aptamers can identify the lesion cells, recognise specific molecules, which open up a new way for the targeted therapy and biological detection. Based on special properties of nanomaterials and the high selectivity, high specificity of aptamers, this thesis has developed novel targeted drug deliery system and biological molecules detector. The details are summarized as follows:We reported an efficient cell-targeting and intracellular controlled-release drug delivery system based on MSN-PEM-Aptamer conjugates. Mesoporous silica nanoparticles (MSN) were employed as drug container for their high loading efficacy and well biological compatibility. Polyelectrolyte multilayers (PEM) were used to prevent the premature leakage of drugs during the delivery process and controllably release drugs under reducing conditions. Finally, a cancer cell-specific DNA aptamer was selected as the targeting recognition molecule for its high cell recognition. The data showed in vitro release behaviors and cell experiment demonstrated that this system had an excellent redox stimuli-response property and targeted delivery effect.A novel cell-type specific and stimuli controlled-release drug delivery vehicle based on the aptamer-modified Fe₃O₄-PEM conjugate was designed. Fe₃O₄ nanoparticles were employed as drug container for their high loading efficacy, sensitive magnetic response and well biological compatibility. The cross-linked polyelectrolyte multilayers (PEM) were used to cap the porous channels of Fe₃O₄ particles. The obtained Fe₃O₄-PEM conjugate is stable in physiological condition while is tend to deconstruct in response to intracellular or reduced environment. Furthermore, due to the high cell-recognition of aptamer tailed on the Fe₃O₄-PEM conjugate, the uptake of Fe₃O₄-PEM-aptamer particles by targeted cells could be enhanced, which resulting in high cellular cytotoxicity. Therefore, by combination of excellent magnetic responsivity, stimuli-respond release kinetics and high cell-recognition features, this multifunctional conjugate is very attractive for site-specific drug delivery applications.The specific reaction between the aptamer and target substance in the immune assay can be used for molecule detection. In view of the particular property of gold nanoparticles (AuNPs) in the immune assay, we introduced a kind of AuNPs probe based on Au-WNJ-aptamer conjugate for protein detection. First, the surface of AuNPs were modified with functional polyelectrolyte (WNJ). The modified AuNPs were stable in a series of harsh environment. The Au-WNJ-aptamer conjugate was obtained after the aptamer was linked to the surface of Au nanoparticles. This conjugate was demonstrated as a sensitive protein detector with high selectivety. And this approach can be applied to other rapid visual protein detection.