Preparation And Behavior Of Keratin-based Polymer Hydrogels

Feather keratin, as a natural polymer material, is not only a rich inexpensive source, butalso has a good biocompatibility and biodegradability. Because its more cystine content,Feather keratin has physicochemical properties, but it is easily protease and has poormechanical properties. Modifying its structure can broaden the application areas of featherkeratin. In this paper, uses feather keratin (FK) as a raw material, while vinyl pyrrolidone(NVP) and N-isopropyl acrylamide (NIPAm) as comonomers, to prepare the environmentalsensitivity intelligent hydrogels. The structure, thermal stability and hydrogel surfacemorphology of copolymers has been characterized by using flourier-infrared spectrometry(FT-IR), thermogravimetric analysis (TG) and scanning electron microscope (SEM),respectively.Firstly, based on the introduction of the hydrogel, the detailed description of the variousclassification methods for hydrogels is given. And the status of several typical protein-basedpolymer hydrogels were reviewed, such as soy protein isolate, zein, collagen protein, wheyprotein, silk protein, keratin and so on are all discussed. Finally, the type of polymerdegradation and degradation mechanism of hydrogels are described.Secondly, a novel drug carrier with graft polymerization hydrogels (FK-PVP-G) basedon feather keratin (FK) and polyvinyl pyrrolidone (PVP) is reported. The structure, thermalstability and hydrogel surface morphology of copolymers has been characterized by usingFT-IR, TG and SEM, respectively.SEM pictures show that the FK-PVP-G have an porestructure which can also be used as a drug carrier. TG results indicate that the thermal stabilityof FK-PVP-G has been significantly improved. Then, FK-PVP-G swollen properties havebeen proved. And the results show a good performance of the swelling properties, which canbe up to22.4(g/g) in water. And in simulated gastric fluid for FK-PVP-G biodegradabilitytests, found that, after17hours, FK-PVP-G hydrogel blocks disappear, indicating that thehydrogel has a good biodegradability. Besides, the vitro drug release behavior of FK-PVP-Gis investigated under different environments by using model drugs such as Bovine SerumAlbumin (BSA) and Rhodamine B (RB). The resust shows that FK-PVP-G for small moleculeloading efficiency is32.6%and macromolecular loading efficiency is98.5%. At a highertemperature (50℃),to small molecule drugs (RB) released, FK-PVP-G has the bestperformance, with the cumulative release rate up to82.4%. For macromolecular drugs, FK-PVP-G release has the best performance at body temperature (37℃), with thecumulative release rate up to35.3%.Thirdly, the NIPAm and PVP are introduced as monomers to prepare FK-based hydrogelFK-PNIPAm-PVP-G. The structure, thermal stability and hydrogel surface morphology ofcopolymers has been characterized by using FT-IR, TG and SEM, respectively.SEM picturesshow that the FK-PNIPAm-PVP-G have an pore structure which can also be used as a drugcarrier. TG results indicate that the thermal stability of FK-PNIPAm-PVP-G has beensignificantly improved. Then, FK-PNIPAm-PVP-G swollen properties have been proved.And the results show a good performance of the swelling properties, which can be up to6.4(g/g) in water. And in simulated gastric fluid for FK-PNIPAm-PVP-G biodegradability tests,found that, after17hours, a mount of FK-PNIPAm-PVP-G hydrogel blocks disappear,indicating that the hydrogel has a good biodegradability. Besides, the vitro drug releasebehavior of FK-PNIPAm-PVP-G is investigated under different environments by usingmodel drugs such as Bovine Serum Albumin (BSA) and Rhodamine B (RB). The resustshows that FK-PNIPAm-PVP-G for small molecule loading efficiency is33.3%andmacromolecular loading efficiency is120.6%. At a higher temperature (50℃),to smallmolecule drugs (RB) released, FK-PNIPAm-PVP-G has the best performance, with thecumulative release rate up to82.5%. For macromolecular drugs, FK-PNIPAm-PVP-Grelease has the best performance at body temperature (37℃), with the cumulative releaserate up to36.4%.Finally, a temperature-sensitive microgel FK-PNIPAm-MG has been prepared, in whichfeather keratin (FK) is a starting material while N-isopropyl acrylamide (NIPAm) ismodifying monomers. By using FT-IR, TG and SEM respectively, the structure, thermalstability and hydrogel surface morphology of microgel FK-PNIPAm-MG are characterized.The results show that FK-PNIPAm-MG has an excellent temperature stimuli-responsive. TheLCST was at30-32℃. And in simulated gastric fluid for FK-PNIPAm-MG biodegradabilitytests, found that, after11hours, FK-PNIPAm-MG hydrogel blocks disappear, indicating thatthe hydrogel has a good biodegradability. Besides, the vitro drug release behavior ofFK-PNIPAm-MG is investigated under different environments by using model drugs such asBovine Serum Albumin (BSA) and Rhodamine B (RB). The resust shows thatFK-PNIPAm-MG for small molecule loading efficiency is38.6%and macromolecular loading efficiency is159.2%. At a higher temperature (50℃),to small molecule drugs (RB)released, FK-PNIPAm-MG has the best performance, with the cumulative release rate up to81.6%. For macromolecular drugs, FK-PNIPAm-MG release has the best performance atbody temperature (37℃), with the cumulative release rate up to14.9%.To be concluded, the paper prepares an excellent biodegradability polymer materialFK-PVP-G and temperature stimuli-responsive sensitively polymer materialsFK-PNIPAm-PVP-G and FK-PNIPAm-MG, showing a good release property in vitro. Thisresearch broadens the study range of natural polymer protein-based drug carrier. There is nodoubt that it will have a bright application prospect in biomedical field.