Preparation And Application Of Several Functional Nanocarrier Systems

The contents of this paper could be divided into three parts:(1) Amphiphilicchitosan derivative was synthesized by carboxymethyl chitosan (CMCs). Themicelle properties and in vitro release were also studied in detail;(2) A pHresponsive hybrid macromolecule was prepared by emulsion polymerization withamphiphilic chitosan derivative and acrylic acid (AA) monomer. We also studied thein vitro release with pH-responsive.(3) SiO2was used as a template to fabricatethermo-responsive hydrogel, the behavior of temperature responsive and drugloading capacities were also studied.A novel amphiphilic chitosan derivative of N,N-dimethylhexadecylcarboxymethyl chitosan (DCMCs) was synthesized by usingN,N-dimethylhexadecylamide and biocompatible, biodegradable, nontoxic CMCs.The physical properties of DCMCs were characterized by Fourier transform-infraredspectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (H NMR), X-raydiffraction (XRD) and differential scanning calorimetry (DSC). The MTT assaysuggested that the DCMCs had a low toxicity to L929cell lines. DCMCs can formcore–shell micelles with low critical micelle concentration (31mg/L) according topyrene-fluorescence method. The micelle exhibited closed and spherical shape withpositive charge (+50.7mV) and narrow sizedistribution (199.1nm, PDI0.44) bytransmission electron microscope (TEM) and atomic force microscope (AFM).Vitamin D3(VD3) was initially used to load into the core–shell micelles, and thesolubility of VD3was improved with higher encapsulation efficiency (53.2%). Thein vitro release processes of VD3from the core–shell micelles were initially rapidand then followed by a sustained release. The Higuchi model was the most suitablefor describing the entire release procedure. DCMCs core–shell micelles arepromising carriers for VD3and other hydrophobic bioactive food factors.A pH responsive hybrid macromolecule (DCMCs-PAA) was prepared byemulsion polymerization with DCMCs and acrylic acid (AA) monomer, of which theammonium persulfate was used as initiator. The physical properties of DCMCs-PAAwere characterized by FT-IR and1H NMR. The critical aggregation concentration(CAC) was determined as95mg/L with pyrene-fluorescence method. The results of TEM and size distribution demonstrated that the particles had different morphologyand potential in diverse pH conditions. VD3was also used as a model molecule toprepare VD3-loaded nanoparticle, in vitro release of VD3from the nanoparticle indifferent pH solution indicated that the VD3-loaded micelle has the highestaccumulative release (69.2%) in simulated intestinal fluid (SIF), while the lowest(42.1%) in simulated gastric fluid (SGF). Therefore, the nanoparticle has a potentialuse in pH site-specific release.Temperature-sensitive nanocapsules were prepared using SiO2as template andpoly(N-isopropylacrylamide)(PNIPAm) as temperature-sensitive polymers,respectively. And the characterizations were investigated by TEM, FT-IR, TGA andUV techniques. Nanocapsules were applied to load of malachite green. The resultsindicated that PNIPAm was grafted successfully into the surface of SiO2. Thenanocapsules were formed after SiO2removal by HF solutions. The nanocapsuleshave the ability of reversible temperature sensitive with higher loading capability.The loading capability of nancapsules was decreased with increasing of temperature.Thus, the application of such temperature-sensitive nanocapsules might offer apotential technology for controlled delivery.