Interaction Mechanism Between Two/Three Dimensional Nanoassemblies And Biomolecules/Cells

In this paper,we fabricated two/three-dimensional nanoassemblies and study the interaction mechanism between nanostructures and biomolecules or cells.Through precise DNA molecule self-assembly,core-satellite nanostrctures were fabricated as chiral sensor or fluorescent sensor and used for sensitive dections.The detection targets varied from biotoxin to thrombin and miRNA.Moreover,we fabricated two-dimensional monolayer nanoparticle film using gas-liquid interface method,and investigated the interaction between nanoparticle film and cells.Firstly,a chiral-aptasensor for ochratoxin A?OTA?detection based on Au core-Ag nanoparticle satellite assemblies was fabricated.High yields of Au core-Ag NP satellite assemblies were prepared in the aqueous phase and the optical properties of the Au core-Ag NP satellite assemblies were investigated in detail.As the different concentrations of OTA target,the assembly degree of the architecture varied and which led to the corresponding chiral signals.The developed method for OTA detection with excellent linear range from 1 to50 pg/mL showed high selectivity for OTA and the limit of detection as low as 0.16 pg/mL.The feasibility of this method was demonstrated by performing recovery experiment using negative red wine samples,excellent recovery ranged from 90%to 105%was achieved,and indicated promising applications.Secondly,NaGd F₄:Yb,Er nanoparticles?with up-conversion?UC?fluorescence?were used to build an“off-on”switch based on Au core-UC satellites for thrombin detection.We fabricated the fluorescence sensor using thrombin aptamer modified Au core and complementary sequence modified UC satellites in liquid phase.With optimized assembled conditions,the yield of Au core-UC satellites achieved 80%.The fluorescence of UC nanoparticles quenched when satellite NP attached to Au core NP.Thrombin aptamer on the surface of Au core would bind to targets when thrombin existed in the system,then UC satellites were released and the quenched fluorescence recovered.The sensor showed high specificity for thrombin compared with other biomolecules and the limit of detection reached3.5 fg/mL.Application of this sensor to detect targets in human serum also achieved satisfactory results.Thirdly,a DNA-driven gold-quantum dot?Au-QD?core-satellite nanostructure was fabricated to directly quantify intracellular miRs in living systems.The Au-QD core-satellite probe underwent a conformational switch upon binding to intracellular miR-21,activating fluorescence.The developed nanostructures demonstrated superior stability and excellent specificity in the detection of intracellular miRs.The results showed that the linear intracellular detection range was from 0.11 to 40.3 amol/ng _RNA with a limit of detection?LOD?of 0.05 amol/ng_RNA.The self-assembled architecture was also applied for guiding high-quality imaging of miR in vivo.The proposed Au-QD core-satellite nanostructure has potential utility in the ultrasensitive bioanalysis of cancer markers.Forthly,we introduced a monolayer plasmonic chiral Au nanoparticle?NP?film modified with L-or D-penicillamine?Pen?,developed for cell growth,differentiation,and retrieval.The monolayer film displayed high chiroptical activity,with circular dichroism values of 3.5 mdeg at 550 nm and 26.8 mdeg at 775 nm.The L-Pen-NP film accelerated cell proliferation,whereas the D-Pen-NP film had the opposite effect.These phenomena were caused by a stereospecific interaction between fibronectin and the chiral NP film.Cells on the L-Pen-NP film displayed bipolar differentiation,whereas multipolar neurite outgrowth occurred on the D-Pen-NP film.Taking advantage of the broad plasmon absorbance band in the red and near-infrared region,remote irradiation with light?808 nm laser?was chosen to noninvasively harvest the cells.Because the chiral film preferentially absorbed left-or right-handed light,left circularly polarized?LCP?light improved the efficiency of cell detachment up to 91.2%for L-Pen-NP film and non-invasive cell harvest.These findings will facilitate the development of cell culture in biomedical application and could help to understand the natural homochirality.