Biointerface Engineering For Enhanced Biomolecule Interaction

Biomolecules are basic structural units of cells.They perform a variety of physiological functions,allowing cell to maintain a wide range of life activities.Molecular recognition between biomolecules such as nucleic acids-proteins,protein-protein,protein-small molecule etc.plays a vital role in life science.Trapping the molecular interaction and identifying targets are very important to understand biological mechanism and discover biomarker.However,recognition force between biomolecules are mostly non-covalent bonding,such as Van der Waals interactions,hydrogen bonding and hydrophobicity,which are weak,transient or pH-dependent interactions.The fragile interaction makes it hard for target identification and handers the way to protein discovery.Aiming at enhancing the molecular recognition,this thesis performed the following three parts of work.1)Photo-reactive probe for aptamer labelling and biomarker discovery.A photo-reactive functional labelling reagent,diazirine phosphoramidite,was designed and synthesized for easy and flexible site specific labelling of oligonucleotides with the diazirine moiety.Diazirine has the advantages of high crosslinking efficiency,small size and excellent chemically stability,which are highly desirable for use in aptamer labelling.The crosslinking efficiency,specificity were evaluated by incorporated in three different aptamers.This new reagent allows facile photo-crosslinking of oligonucleotide with its interacting partner for a variety of applications,including tertiary structure determination,molecular interaction study and biomarker discovery.2)Multifunctional DNA dendrimer for cancer theranostic.A multifunctional DNA dendritic nanostructure was developed for targeted cancer cell imaging and drug delivery.It’s constructed from Y-shaped building blocks with predesigned base-pairing hybridization.With controllable step-by-step self-assembly,the programmable DNA dendrimer has several appealing features,including facile modular design,excellent biostability and intercalated anticancer drugs.By incorporated aptamer in the outside layer,DNA dendrimer showed better binding affinity than individual aptamers which benefited from the multivalent effect.A model chemotherapeutic anticancer drug,doxorubicin,was delivered via these aptamer-based DNA dendrimers and exerted a potent toxicity for target cancer cells with low side effects.This controllable aptamer-based DNA dendrimer is a promising candidate for biomedical applications.3)Microfluidic technology for rare cells enrichment.A series of high-performance microfluidic chips were designed and constructed.The microarrays in the chip were designed according to the principle of deterministic lateral displacement(DLD).Micro fluid formed by DLD microarrays can guide cell’s path in the microchannel which can increase the collision efficiency of targeted cell with micropillars and deplete background cells.Equipped with specific antibody on the surface of micropillars,cell can be selectively captured among the plenty of blood cells.Based on these microfluidic chips,a non-invasive prenatal diagnosis method based on fetal cell capture has been developed to achieve efficient isolation and enrichment of fetal cells in pregnant women’s peripheral blood.With the help of immunostaining,fetal cell can be identified as early as 7 pregnancy weeks in 2 mL maternal blood.Combining single cell manipulation and next-generation high-throughput sequencing,fetal genetics mapping can be achieved for non-invasive and accurate prenatal diagnosis.