Microencapsulation Of Polymer And Metal Nanoparticles In Cells

The cells of baker's yeast are spherical or ellipsoidal fungus with a diameter of approximately 2-5?m.The envelopes of yeast cells are intriguing single bag-shaped structures and have been used to protect volatile components from premature evaporation about 40 years ago.Recently,researchers have found that 1,3-?-glucans,the main components of yeast cell wall,could be phagocytosed via receptor-mediated cell uptake by macrophages cells.In this article,we encapsulated polymers and metal nanoparticles in yeast cells and formed hierarchical macroparticles packaged by yeast cell envelopes.We hope this nanoparticles can realize the delivery and function in living cells through package by yeast envelopes.This thesis summarized the work of the following three parts:(1)We encapsulated polymer nanoparticles in yeast cells and studied the up-take of the yeast-encapsulated particles by macrophages cells.We constructed a hierarchical particles of yeast cells encapsulating polymer nanoparticles via in situ free radical polymerization of vinyl monomers inside cells.Proper degree of cell autolysis is important for achieving high yields of polymer nanoparticles inside cells.When styrene is used as the model monomer,the nature of polymerization initiating systems affects the morphologies of obtained particles.Pomegranate-like yeast cellular particles carrying PS nanoparticles are obtained by a AIBN-initiated free radical polymerization of styrene inside yeast cells.The in vitro tests showed that the macrophage cells could selectively take up the yeast particles bearing PS nanoparticles.These yeast microparticles carrying polymer nanoparticles can act as Trojan particles to carry and release polymer nanoparticles in a certain circumstance.Because of the controlled permeability of yeast membrane,the methodology developed in this work can be extended to produce cells bearing water-soluble polymers with big molecular weights.The yeast Trojan particles may find a broad scope of applications,not only as the Trojan particles for drug delivery but also as arterial embolic agents of tumors,as bioadsorption and separation materials,etc.(2)We encapsulated silver and palladium nanoparticles in yeast and bacillus megaterium cells.Metal irons were encapsulated inside yeast cells through water or toluene solution form and then they were reduced and trapped in yeast cells using different methods.We can make the particle distribution at different positions of the yeast by controlling the solvent type and reduction method.When bacillus cells were used instead of yeast cells,we also successfully encapsulated metal nanoparticles.And this method can be extended to other kinds of metals.Many important intracellular biochemical reactions are modulated by transition metals,typically in the form of metalloproteins.The ability to carry out metal nanoparticles inside a cell would allow researchers to manipulate or interrogate innumerable biological processes.(3)We encapsulated manganese carbonate in yeast cells and realized the autonomous movement of this particles.Through heating yeast cells with the solution of potassium permanganate,we encapsulated manganese compound in yeast cells and this manganese compound is proven to be manganese carbonate.We observed a rocket-like self-propelled phenomenon after putting this particles in hydrogen peroxide and the speed of this particles could achieve 0.3 mm/s.As a result of a few fold of the cell surface and other shape asymmetry,cells generated different volume gas in different directions causing the movement of cells.We will control the directions of this particles through encapsulating magnetic particles in yeast cells in the future experiments.We have encapsulated various kinds of interesting structures in yeast cells and realized a lot of Functions.All these functions can be concentrated in one particle system to set up new multifunctional particles.This will make our yeast-cell-based microencapsulation systems have unlimited potential in the future.