skip to main content

Explore Research Products in the NSF-PAR

Title: Electrospun Silk-Boron Nitride Nanofibers with Tunable Structure and Properties
In this study, hexagonal boron nitride (h-BN) nanosheets and Bombyx mori silk fibroin (SF) proteins were combined and electrospun into BNSF nanofibers with different ratios. It was found that the surface morphology and crosslinking density of the nanofibers can be tuned through the mixing ratios. Fourier transform infrared spectroscopy study showed that pure SF electrospun fibers were dominated by random coils and they gradually became α-helical structures with increasing h-BN nanosheet content, which indicates that the structure of the nanofiber material is tunable. Thermal stability of electrospun BNSF nanofibers were largely improved by the good thermal stability of BN, and the strong interactions between BN and SF molecules were revealed by temperature modulated differential scanning calorimetry (TMDSC). With the addition of BN, the boundary water content also decreased, which may be due to the high hydrophobicity of BN. These results indicate that silk-based BN composite nanofibers can be potentially used in biomedical fields or green environmental research.  more » « less
Award ID(s):
1809541
NSF-PAR ID:
10245299
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Polymers
Volume:
12
Issue:
5
ISSN:
2073-4360
Page Range / eLocation ID:
1093
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ( , International Journal of Molecular Sciences)
    null (Ed.)
    Biopolymer composites based on silk fibroin have shown widespread potential due to their brilliant applications in tissue engineering, medicine and bioelectronics. In our present work, biocomposite nanofilms with different special topologies were obtained through blending silk fibroin with crystallizable poly(L-lactic acid) (PLLA) at various mixture rates using a stirring-reflux condensation blending method. The microstructure, phase components, and miscibility of the blended films were studied through thermal analysis in combination with Fourier-transform infrared spectroscopy and Raman analysis. X-ray diffraction and scanning electron microscope were also used for advanced structural analysis. Furthermore, their conformation transition, interaction mechanism, and thermal stability were also discussed. The results showed that the hydrogen bonds and hydrophobic interactions existed between silk fibroin (SF) and PLLA polymer chains in the blended films. The secondary structures of silk fibroin and phase components of PLLA in composites vary at different ratios of silk to PLLA. The β-sheet content increased with the increase of the silk fibroin content, while the glass transition temperature was raised mainly due to the rigid amorphous phase presence in the blended system. This results in an increase in thermal stability in blended films compared to the pure silk fibroin films. This study provided detailed insights into the influence of synthetic polymer phases (crystalline, rigid amorphous, and mobile amorphous) on protein secondary structures through blending, which has direct applications on the design and fabrication of novel protein–synthetic polymer composites for the biomedical and green chemistry fields. 
    more » « less
  2. ; ( , RSC Medicinal Chemistry)
    The electrospinning of hydrocortisone/cyclodextrin complex nanofibers was performed in order to develop a fast-dissolving oral drug delivery system. Hydrocortisone is a water-insoluble hydrophobic drug, yet, the water solubility of hydrocortisone was significantly enhanced by inclusion complexation with hydroxypropyl-beta-cyclodextrin (HP-β-CyD). In this study, hydrocortisone/HP-β-CyD complexes were prepared in aqueous solutions having molar ratios of 1/1, 1/1.5 and 1/2 (hydrocortisone/HP-β-CyD). Highly concentrated aqueous solutions of HP-β-CyD (180%, w/v) were used for hydrocortisone/HP-β-CyD systems (1/1, 1/1.5 and 1/2) in order to perform electrospinning without the use of an additional polymer matrix. The turbidity of hydrocortisone/HP-β-CyD (1/1 and 1/1.5) aqueous solutions indicated the presence of some uncomplexed crystals of hydrocortisone whereas the aqueous solution of hydrocortisone/HP-β-CyD (1/2) was homogeneous indicating that hydrocortisone becomes totally water-soluble by inclusion complexation with HP-β-CyD. Nonetheless, the electrospinning of hydrocortisone/HP-β-CyD systems (1/1, 1/1.5 and 1/2) successfully yielded defect-free uniform nanofibrous structures. Moreover, the electrospinning process was quite efficient that hydrocortisone was completely preserved without any loss yielding hydrocortisone/HP-β-CyD nanofibers having the initial molar ratios (1/1, 1/1.5 and 1/2). The structural and thermal characterization of the hydrocortisone/HP-β-CyD nanofibers revealed that hydrocortisone was totally inclusion complexed with HP-β-CyD and was in the amorphous state in hydrocortisone/HP-β-CyD (1/2) nanofibers whereas some uncomplexed crystalline hydrocortisone was present in hydrocortisone/HP-β-CyD (1/1 and 1/1.5) nanofibers. Nevertheless, hydrocortisone/HP-β-CyD (1/1, 1/1.5 and 1/2) complex aqueous systems were electrospun in the form of nanofibrous webs having a free-standing and flexible nature. The hydrocortisone/HP-β-CyD (1/1, 1/1.5 and 1/2) nanofibrous webs have shown fast-dissolving behavior in water or when they were in contact with artificial saliva. Yet, the hydrocortisone/HP-β-CyD (1/2) nanofibrous web dissolved more quickly than the hydrocortisone/HP-β-CyD (1/1 and 1/1.5) nanofibrous webs due to the full inclusion complexation and the amorphous state of hydrocortisone in this sample. In short, the results suggest that polymer-free electrospun nanofibrous webs produced from hydrocortisone/HP-β-CyD could be quite applicable for fast-dissolving oral drug delivery systems. 
    more » « less
  3. ; ; ; ; ( , International Journal of Molecular Sciences)
    Silk fibroin (SF) is a protein polymer derived from insects, which has unique mechanical properties and tunable biodegradation rate due to its variable structures. Here, the variability of structural, thermal, and mechanical properties of two domesticated silk films (Chinese and Thailand B. Mori) regenerated from formic acid solution, as well as their original fibers, were compared and investigated using dynamic mechanical analysis (DMA) and Fourier transform infrared spectrometry (FTIR). Four relaxation events appeared clearly during the temperature region of 25 °C to 280 °C in DMA curves, and their disorder degree (fdis) and glass transition temperature (Tg) were predicted using Group Interaction Modeling (GIM). Compared with Thai (Thailand) regenerated silks, Chin (Chinese) silks possess a lower Tg, higher fdis, and better elasticity and mechanical strength. As the calcium chloride content in the initial processing solvent increases (1%–6%), the Tg of the final SF samples gradually decrease, while their fdis increase. Besides, SF with more non-crystalline structures shows high plasticity. Two α- relaxations in the glass transition region of tan δ curve were identified due to the structural transition of silk protein. These findings provide a new perspective for the design of advanced protein biomaterials with different secondary structures, and facilitate a comprehensive understanding of the structure-property relationship of various biopolymers in the future. 
    more » « less
  4. ( , Surfaces and interfaces)
    Co-axial electrospinning is an efficient technique to develop core-shell or hollow nanofibrous structures. In this study electrospun carbon nanofibers with three different morphologies, i.e. solid nanofibers with porous structure (P-ECNF), hollow nanofibers with solid wall (H-ECNF), and hollow nanofibers with porous wall (HP-ECNF) were developed through bicomponent electrospinning and co-axial electrospinning of polyacrylonitrile (PAN) and poly (methyl methacrylate) (PMMA) by varying proportion of the sacrificial PMMA. Through comparative electrochemical analyses, it is revealed that the primary factors for electrochemical performance, i.e. specific capacitance, of the electrospun carbon nanofibrous materials are mesopore volume and total pore volume. The hollow structure as well as ordered carbon structure and intact fiber structure also benefits electrolyte transfer and subsequent electrochemical performance but is secondary. Overall the porous carbon nanofibrous electrode material from electrospinning PAN/PMMA (50/50) solution (P-ECNF-50-50) outperformed those hollow and hollow-porous counterparts from co-axial electrospinning and demonstrated the largest specific capacitance due to the largest mesopore volume as well as the largest total pore volume. This electrode material also showed excellent cycling stability (without any loss of specific capacitance) after 3,000 cycles of charging and discharging. It even showed some increase of specific capacitance with cycling test due to its relatively large amount of micropores. 
    more » « less
  5. ; ( , Food & Function)
    null (Ed.)
    The encapsulation of food/dietary supplements into electrospun cyclodextrin (CD) inclusion complex nanofibers paves the way for developing novel carrying and delivery substances along with orally fast-dissolving properties. In this study, CD inclusion complex nanofibers of Vitamin-A acetate were fabricated from polymer-free aqueous systems by using the electrospinning technique. The hydroxypropylated (HP) CD derivatives of HPβCD and HPγCD were used for both encapsulation of Vitamin-A acetate and the electrospinning of free-standing nanofibrous webs. The ultimate Vitamin-A acetate/CD nanofibrous webs (NWs) were obtained with a loading capacity of 5% (w/w). The amorphous distribution of Vitamin-A acetate in the nanofibrous webs by inclusion complexation and the unique properties of nanofibers ( e.g. high surface area and porosity) ensured the fast disintegration and fast dissolution/release of Vitamin-A acetate/CD-NW in a saliva simulation and aqueous medium. The enhanced solubility of Vitamin-A acetate in the case of Vitamin-A acetate/CD-NW also ensured an improved antioxidant property for the Vitamin-A acetate compound. Moreover, Vitamin-A acetate thermally degraded at higher temperature in Vitamin-A acetate/CD-NWs, suggesting the enhanced thermal stability of this active compound. Here, HPβCD formed inclusion complexes in a more favorable way when compared to HPγCD. Therefore, there were some uncomplexed Vitamin-A acetate crystals detected in Vitamin-A acetate/HPγCD-NW, while Vitamin-A acetate molecules loaded in Vitamin-A acetate/HPβCD-NW were completely in complexed and amorphous states. Depending on this, better solubilizing effect, higher release amount and enhanced antioxidant properties have been provided for the Vitamin-A acetate compound in the case of Vitamin-A acetate/HPβCD-NW. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email