Preparation And Biological Detection Of Magnetoelastic Nanosensing Chips

Driven by the rapid economic development and technological innovation,humans have attached great importance to their own health problems,and the early detection and diagnosis of diseases have become an inevitable trend of the development of the times.The traditional diagnosis method is mainly to use large-scale hospital equipment to detect patients’tissues or blood samples.This method is mature and accurate,but it is relatively expensive and time-consuming in the initial stage of disease prevention and elimination.In relatively backward areas,such medical equipment cannot be popularized.With the development of science and technology,micro-miniature biosensing equipment has good application prospects in the field of disease marker detection.Investing in clinical testing needs further improvement.Therefore,it is necessary to develop a biosensing chip with simple preparation process,low cost,short time consumption and high sensitivity for the detection of disease markers.Magnetoelastic sensing chips have attracted widespread attention because of their low cost,small size,portability,simple operation,and fast response.They have become popular sensing substrates for biosensors for many years.The magnetoelastic sensing chip is based on the magnetoelastic coupling effect,which generates the mutual conversion of magnetic energy and mechanical energy under the action of an external magnetic field or an external stress to realize the process of converting the recognition reaction into a recordable frequency signal or permeability signal.It is of great value and significance to prepare a high-performance magnetoelastic sensing chip and apply it to the detection of disease markers.Therefore,this thesis proposes two types of magnetoelastic sensing chips:magnetostrictive immunosensing chip and paper-based magnetoelastic biosensing chip,and applies them to the detection of human serum albumin（HSA）,a marker of diabetic nephropathy.In-depth study of their various sensing characteristics provides new ideas for the preparation of biosensing chips,and provides an effective method for early prevention of diabetic nephropathy.The specific research of this thesis is as follows:（1）The sensing mechanism and preparation process of the magnetoelastic sensing chip are studied,the coupling effect of the magnetoelasticity is deeply analyzed,and the mechanism of its application in biological detection is studied.Based on the magnetostrictive effect,the magnetostrictive material after surface micro-nano processing is cut into small chips with a size of5mm×1mm×28μm,and a magnetostrictive sensing chip is prepared,which reflects the test object through the change of the resonance frequency response.Based on the magnetoelastic effect,NiFe₂O₄ nanoparticles were combined with cellulose paper to obtain NiFe₂O₄/paper-based nanocomposite material,and thiolated gold nanoparticles were physically deposited on the surface to prepare a paper-based magnetoelastic sensing chip.Changes in the magnetic properties of the sensing chip enable biological detection.（2）A magnetostrictive immunosensing chip is proposed.The surface of gold-plated magnetostrictive sensing chip is modified with mercaptoethylamine to form a self-assembled film.Based on the principle of antibody-antigen specific binding,an anti-HSA antibody was immobilized on the surface by a covalent bond for detection of HSA.The modification of bovine serum albumin can not only avoid non-specific adsorption,but also reduce the steric hindrance effect.The antibody fixing process was characterized by Raman spectroscopy,X-ray photoelectron spectroscopy and atomic force microscopy.The experimental results show that the prepared magnetostrictive immunosensing chip can realize the detection of HSA with high sensitivity,high specificity and high stability.（3）Propose a paper-based magnetoelastic biosensing chip,based on antibody immunoassay,on the surface of NiFe₂O₄/paper with thiolated gold nanoparticles deposited on the surface,the modified capture probe anti-HSA antibody is used to detect macromolecular protein HSA.Using energy spectrum analysis,scanning electron microscopy and Fourier infrared spectroscopy analysis confirmed that NiFe₂O₄ nanoparticles successfully attached to cellulose paper.In order to improve the sensing response of the paper-based magnetoelastic biosensing chip,the working concentration of NiFe₂O₄ nanofluid and the number of times the NiFe₂O₄ nanofluid impregnated paper were optimized during the preparation process.The experimental results show that the prepared sensing chip achieves low-cost,specific and sensitive detection of HSA,and the detection limit is lower than the health diagnosis standard.In addition,the proposal of NiFe₂O₄/paper provides a new,environmentally friendly and convenient sensing substrate for magnetoelastic biosensing chips.