Preparation And Application Of Hydrogel Micro- And Nano- Capsules

Microcapsulation is the technology which utilizes natural or synthetic polymer wall materials to encapsulate solid particles,liquid droplets or gas core materials,forming capsules with diameters in the range of 1 nm¹000?m.Microencapsulation can isolate the external environment and improve the storage stability of core materials.Systems of many different types of capsules in versatile forms were invented to improve volatility and instability of core materials.However,new problems came along as well,such as large particle sizes,toxic monomers and low encapsulation efficiency.Hydrogel nanoparticles with diameters in the range of tens to hundreds of nanometers,have attracted especially interest because of their significant importance in fundamental studies.They can show a much more rapid response to micro environmental stimuli such as temperature,p H,light and magnetic,compared with bulk ones.Hydrogels are extremely important in textile,pharmaceutical and other fields.Herein,in order to prepare robust capsule systems with enhanced capability,the design,preparation and evaluation of several capsule systems based on the hydrogels platform were conducted as follows:1.It is expensive to obtain optimal conditions through conventional single factor experiments.Response surface method?RSM?was applied in order to solve these problems.According to the RSM,the optimal parameters to achieve the highest yield of encapsulation efficiency was achieved.Poly?1,4-butanediol dimethacrylate?hydrogel microcapsules were synthesized by interfacial free-radical polymerization,in which a 1,4-butanediol dimethacrylate?BDDMA? monomer was self-crosslinked to form a polymer shell.It was found that the fragrance contents on the fabric decreased slowly with an increasing number of washing cycles.The fragrance hydrogel microcapsules had good laundry durability,which is encouraging for applications in textile.2.According to phase separation principle,pseudo-ternary phase diagram was proposed to predict that whether oil in water?O/W?hydrogel capsules can be formed or not.In this work,dementholized peppermint oil was encapsuled by poly?ethylene glycol dimethacrylate?under the guidance of pseudo-ternary phase diagram.The hydrogel nanocapsule can improve the onset evaporation temperature of dementholized peppermint oil?DPO?from 50?to 100?.Further,the hydrogel nanocapsules sizes can be tuned by carbon numbers of monomers,which is of great significance to the controllable preparation of hydrogel nanocapsules with certain size.3.Insituoxidationpolymerizationmethodwasdevelopedtopreparethe poly?N-tert-butylacrylamide-co-acrylic acid?/Fe₃O₄?P?TBA-co-AA?/Fe₃O₄?hydrogel nanocapsules.Firstly,P?TBA-co-AA?nanogels were synthesized through emulsion precipitation polymerization;then P?TBA-co-AA?/Fe₃O₄ hydrogel nanocapsules were synthesized by in situ oxidation of Fe²⁺into Fe₃O₄ nanoparticles.P?TBA-co-AA?/Fe₃O₄ hydrogel nanocapsules had a super paramagnetic property and a significant contrast enhancement,meaning the magnetic hydrogel nanocapsules had high sensitivity and clear imaging as magnetic resonance imaging?MRI?contrast agent.4.The hydroxypropyl methylcellulose?HPMC?hydrogel nanocapsules loaded with insulin?INS?were prepared under the optimal condition,which had a small size and a low polydispersity index?PDI?.Furthermore,the encapsulated INS can diffuse out slowly from the hydrogel nanocapsules by adjusting the temperature or pH,indicating that the hydrogel nanocapsules have a great potential to serve as a novel long-acting INS release formulation.5.Hydrogel nanoparticles were composed of different monomers based on N-isopropyl acrylamide?NIPAm?.We have shown that the introduction of aromatic monomers results in nanoparticles?NPs?with higher affinity to the target protein.The synthetic hydrogel NPs can neutralize the toxin in vitro and neutralization was independent of the presence of an abundant serum protein with similar nonspecific affinity.These results suggested that synthetic hydrogel NPs can be engineered to have an intrinsic affinity to a specific biomacromolecule of snake venom.Hydrogel nanoparticles would offer a low cost alternative to biological affinity agents?antibodies,recombinant proteins,etc.?for biotechnology applications.In summary,novel capsule systems were designed and fabricated based on hydrogels technique.Comprehensive performance of each system was evaluated,and potential applications in various fields were proposed accordingly.This work presents itself as a new reference to the study of effective capsule systems.