Preparation And Application Of Functionalized Janus Composite Nanoparticles

The change of pH in human body and the level of mercury in environment have a very important impact on human life and health,so it is very important to detect these ions in time.Among many methods for detecting intracellular pH,fluorescence method has become a powerful tool for detecting complete cell and subcellular pH because of its high sensitivity,high spatial-temporal resolution and simple operation.It is very important to choose the suitable carrier in fluorescence method.For the common heavy metal pollutant mercury,the traditional analytical methods have many problems,such as complex sample pretreatment,expensive instrument,long analytical cycle and so on.Nano gold and silver materials have become a new favorite in recent years due to their unique surface plasmon resonance effect,but there are also problems such as the inability to separate and recover in time after detection.The Janus particle's ability to combine materials of different properties can solve some of the above problems.Janus particle is a functional particle composed of two surfaces?or internal materials?with different physical or chemical properties.If it can be prepared with a variety of chemical composition and functional partition,it can greatly expand its flexibility and chemical value.Therefore,Janus particles with different functional properties were prepared by surface modification and microfluidic technology,and their applications in the field of optical sensing were developed.The specific research contents are as follows:Chapter 1:The development,preparation and application of Janus particles are reviewed.First,the development history of Janus particles is briefly summarized.Second,the preparation methods of Janus particles and the applicable conditions,advantages and disadvantages of each method are summarized in detail.Applications in the fields of optical sensing and environmental monitoring.Chapter 2:Based on the principle of surface modification,Janus colloidal particles were prepared by Pickering emulsion method.Using silicon dioxide as the raw material,the surface is subjected to amination treatment,and then the aminated silica particles are asymmetrically modified by the Pickering emulsion method.The amino groups exposed on the surface are respectively isothiocyanate and rhodan of isothiocyanate fluorescein.The carboxyl group of the rhodamine B probe was dehydrated and condensed,and finally the Janus composite nanoprobe was synthesized.The Janus composite nanoprobe can detect the ratio of intracellular pH in environments with different pH values,showing good biocompatibility and cell membrane permeability.Working to design and synthesize a new Janus composite nanoprobe,which is expected to provide a new method for detecting the pH value of Janus particles in cells.Chapter 3:Preparation of a simple device based on the principle of microfluidics.The prepared silver nanoparticles and Fe₃O₄ magnetic nanoparticles were dispersed in a sodium alginate solution,and then solidified in a CaCl₂ solution to form Janus particles.Two-phase immiscible and stable Janus particles were prepared by adjusting the ratio of different sodium alginate to silver nanoparticles,magnetic particles,and CaCl₂solution.Detection of Hg²⁺at different concentrations was performed using UV-Vis absorption spectroscopy.Through the detection of actual water samples and recovery rates,the sensor can be directly used for the detection of mercury ions.The Janus particles based on the microfluidic principle designed in this work have a wide detection range and low detection limit,which is expected to provide new ideas for the construction of sensors that detect Hg²⁺.Chapter 4:Raw materials of bovine serum albumin?BSA?are readily available.Fluorescent gold nanoclusters have good optical stability and large Stokes shift,and are often used for the detection of metal ions.So using bovine serum albumin?BSA?as a protective agent and reducing agent,a water-soluble bovine protein-gold nanocluster was prepared.Based on the response of BSA-Au nanoclusters to mercury ions,a method for rapid detection of mercury ions was established.When the Hg²⁺concentration is0-80?g,the fluorescence intensity of the sensor has a good linear relationship and fast response to Hg²⁺,and has good light stability and reversibility.The sensor can be directly used for the detection of actual water samples,and can be separated quickly and efficiently.