Browsing by Author "Ziegler, Gregory R."
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Item Aligned wet-electrospun starch fiber mats(2019-05) Wang, Hui; Kong, Lingyan; Ziegler, Gregory R.; University of Alabama TuscaloosaElectrospinning is a versatile technique to fabricate non-woven fiber mats with an average fiber diameter ranging from nanometers to micrometers. Fibers produced by electrospinning have potential application in numerous fields owing to their light weight, high surface area, and high porosity. In certain applications, anisotropic properties are desired, which may also improve mechanical strength. This study comprehensively documented the feasibility of directed fiber deposition in wet-electrospinning and offers an inexpensive setup for laboratory investigation. Aligned starch fiber mats were produced and the effects of three operational parameters, i.e., rotational speed, drum location, and coagulation bath composition, were evaluated. The alignment of starch fibers was affected by the ethanol concentration in the coagulation bath and drum rotational speed. Coherent fibers could be obtained in all trials except for the one at the lowest ethanol concentration (60% v/v) and highest rotational speed (500 rpm) when the drum was below the liquid. The tensile strength was influenced by the interaction of location and ethanol concentration, and that of rotational speed and ethanol concentration. This study set a promising example of making aligned biopolymer fiber mats and investigating fiber deposition in wet-electrospinning. Aligned starch fiber mats have potential applications in areas such as tissue engineering and as wound dressings.Item Characterization of amylose inclusion complexes using electron paramagnetic resonance spectroscopy(2018-09) Kong, Lingyan; Yucel, Umut; Yoksan, Rangrong; Elias, Ryan J.; Ziegler, Gregory R.; University of Alabama TuscaloosaAmylose is well known to form inclusion complexes with various small molecules including fatty acids. In this study, we prepared amylose inclusion complexes with stearic acid derived spin probes and demonstrated the electron paramagnetic resonance (EPR) spectroscopy as an emerging tool for studying the microstructure and microenvironment of amylose-guest inclusion complex. Two spin probes, namely 5-doxyl-stearic acid (5-DSA) and 16-doxyl-stearic acid (16-DSA), were used as guest molecules in forming amylose-guest inclusion complexes. The molecular dynamics and local polarity of the spin probes and their interaction with amylose in physical mixtures and inclusion complexes were studied using EPR spectroscopy. Complexed guest spin probes could be released when the inclusion complex was dissolved dimethyl sulfoxide (DMSO) and detected by EPR. Since the inclusion complex could not be dissolved in water, the motion of spin probes was restricted in hydrated samples shown by the powder-like slow spectra. Our findings also indicated that the individual association between amylose and the two DSA molecules in forming the inclusion complexes were different. A portion of 16-DSA molecules were not tightly immobilized in the amylose helical channel, but instead were loosely entrapped in the amorphous region of the semicrystalline V6-type amylose. Therefore, EPR spectroscopy provides valuable information on the molecular dynamics and microenvironment of guest molecules and their interaction with amylose in inclusion complex, and can be exploited as a useful tool to study amylose-guest inclusion complex and other host-guest systems.Item Characterization of macromolecular orientation in κ-carrageenan fibers using polarized Fourier-transform infrared spectroscopy(2018-01) Kong, Lingyan; Stapleton, Joshua J.; Ziegler, Gregory R.; University of Alabama TuscaloosaIn the current study, polarized infrared (IR) microspectroscopy was employed to characterize the macromolecular orientation in wet-spun and stretched κ-carrageenan fibers. The fibers were shown to be well oriented by X-ray diffraction, suggesting that the κ-carrageenan molecules were generally aligned along the fiber axis direction. Longitudinal fiber pieces of about 10 μm thick were obtained by focused ion beam (FIB) micromilling. The fiber pieces were examined by polarized IR in transmission mode. Several bands, including those characteristic of κ-carrageenan at 845 and 930 cm⁻¹, were polarization-dependent, demonstrating polarized IR as a useful tool to evaluate macromolecular orientation in carrageenan fibers. Band assignments were discussed by considering the general alignment of molecules and the polarization dependence of vibration modes, and our results agreed well with band assignments from previous reports.Item Characterization of Starch Polymorphic Structures Using Vibrational Sum Frequency Generation Spectroscopy(American Chemical Society, 2014-01-16) Kong, Lingyan; Lee, Christopher; Kim, Seong H.; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaThe polymorphic structures of starch were characterized with vibrational sum frequency generation (SFG) spectroscopy. The noncentrosymmetry requirement of SFG spectroscopy allows for the detection of the ordered domains without spectral interferences from the amorphous phase and also the distinction of the symmetric elements among crystalline polymorphs. The V-type amylose was SFG-inactive due to the antiparallel packing of single helices in crystal unit cells, whereas the A- and B-type starches showed strong SFG peaks at 2904 cm(-1) and 2952-2968 cm(-1), which were assigned to CH stretching of the axial methine group in the ring and CH, stretching of the exocyclic CH2OH side group, respectively. The CH2/CH intensity ratios of the A- and B-type starches are significantly different, indicating that the conformation of hydroxymethyl groups in these two polymorphs may be different. Cyclodextrin inclusion complexes were also analyzed as a comparison to the V-type amylose and showed that the head-to-tail and head-to-head stacking patterns of cyclodextrin molecules govern their SFG signals and peak positions. Although the molecular packing is different between V-type amylose and cyclodextrin inclusion complexes, both crystals show the annihilation of SFG signals when the functional group dipoles are arranged pointing in opposite directions.Item Effect of guest structure on amylose-guest inclusion complexation(2019-12) Kong, Lingyan; Perez-Santos, Diana M.; Ziegler, Gregory R.; University of Alabama TuscaloosaAmylose-guest inclusion complexes are a type of supramolecular host-guest assembly that can provide protection for and controlled release of guest molecules. The successful and efficient complexation between amylose and guest molecules is governed by factors including: guest structure and chemistry, and process method and parameters. Here we investigated the formation, crystalline structure, and thermal stability of amylose inclusion complexes with a total of ten guest molecules differing in alkyl chain length (C10 and C16), molecular shape (linear vs. branched), and functional groups (alcohol, aldehyde, carboxylic acid, and ester). Their ability to complex with amylose was evaluated using two complexation methods (partitioning from water after heating and partitioning from a DMSO/water solution), and two annealing temperatures (60 and 90 °C). The extent of complexation differed for the two methods, likely due to guest solubility and partitioning behavior in the respective solvent systems. Annealing temperature created inclusion complexes of different structure and dissociation temperature using the water approach. Here we suggest that the so-called “Form I” and “Form II” V-type amylose inclusion complexes differ in their crystal size, crystallinity and arrangement of guest molecules in the helical cavity, rather than being amorphous or crystalline as previously reported. Chain length, molecular shape, and functional groups affected the thermal stability of the inclusion complexes. Shorter chain length, unsaturation, and short branched chains formed inclusion complexes with lower dissociation temperatures. We propose the Form II as a tail-to-tail arrangement of molecules in the helices that leaves the functional groups at the helical openings. Guest compounds that either failed to form complexes from water or formed poor complexes were able to form inclusion complexes with amylose using the DMSO approach, suggesting solubility of the guest, flexibility of the amylose chain, or the partitioning of the guest between the solvent and the helix core affected complexation.Item Electrospinning of Octenylsuccinylated Starch-Pullulan Nanofibers from Aqueous Dispersions(Elsevier, 2020-08-21) Li, Songnan; Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaWe aimed to develop a greener process for dry-electrospinning food-grade modified starch through the elimination of organic solvents. The rheological properties and electrospinnability of aqueous dispersions of commercial octenylsuccinylated (OS) starches with various molecular weight (Mw) were investigated, yet only nanofibers with beads or defects could be obtained from OS starch with the highest Mw, i.e., Purity Gum(@) Ultra (PGU). Further improvement in the fiber morphology was achieved by adding pullulan (PUL) as a minor component in the spinning dope. Smooth, continuous, and bead-free nanofibers (147-250 nm) were obtained from the PGU-PUL dispersions. Shown on an electrospinnability map, the successful electrospinning of 12%, 15%, and 20% (w/v) aqueous PGU dispersions required a minimum addition of 6%, 5%, and 3% (w/v) of PUL, respectively. The addition of PUL contributed to establishing sufficient molecular entanglement for electrospinning. This study provides a promising green process to produce starch-based nanofibers for use in various applications, e.g., drug delivery, wound dressing, and tissue engineering.Item Encapsulation and stabilization of β-carotene by amylose inclusion complexes(2018-03) Kong, Lingyan; Bhosale, Rajesh; Ziegler, Gregory R.; University of Alabama TuscaloosaIn the present study, we report a novel composition based on amylose (or starch) inclusion complex with an amphiphilic material as an effective encapsulation platform technology to incorporate guests of interest. Specifically, the encapsulation of β-carotene in amylose-surfactant and amylose/starch-ascorbyl palmitate (AscP) inclusion complexes was investigated. Surfactants of different hydrophilicity/lipophilicity were selected to cover a broad range of HLB values. The formation of the inclusion complexes was characterized by X-ray diffraction and differential scanning calorimetry. The ability of amylose-surfactant system to encapsulate β-carotene was dependent on the HLB value of the surfactants, instead of their ability to induce inclusion complexation. The incorporation of β-carotene hindered amylose-surfactant inclusion complex formation, whereas no significant effect was observed on structural and thermal properties of starch-AscP inclusion complex in the presence of β-carotene. The X-ray diffraction pattern of amylose-AscP-β-carotene showed that β-carotene molecules did not crystallize into a separated phase and thus were suggested to be homogeneously immobilized within the polycrystalline amylose-AscP inclusion complexes. During a storage period of six weeks at 20 and 30 °C, the stability of β-carotene was improved by encapsulation in starch-AscP inclusion complexes compared with that in physical mixtures of the three components.Item Fabrication of kappa-carrageenan fibers by wet spinning: Addition of iota-carrageenan(Elsevier, 2013-01) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaTaking advantage of the gelation process of kappa-carrageenan, we have developed a wet-spinning process to fabricate micro-scale fibers from kappa-carrageenan. Effects of three important spinning parameters, i.e. coagulation bath composition, spinning rate and post-spinning mechanical drawing, on fiber morphological and tensile properties have been discussed. In the present report, we studied the addition of iota-carrageenan on thermal and rheological properties of the bicomponent gels and the fibers spun from them. It was found that kappa- and iota-carrageenan underwent phase separation in the bicomponent gel. Upon addition of i-carrageenan, the diameter and compliance of the blend fiber was increased. (C) 2012 Elsevier Ltd. All rights reserved.Item Fabrication of kappa-Carrageenan Fibers by Wet Spinning: Spinning Parameters(MDPI, 2011-10-11) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaThis study demonstrates the fabrication of kappa-carrageenan fibers by a wet-spinning method and discusses three important spinning parameters: coagulation bath composition, spinning rate and post-spinning mechanical drawing. The as-spun fiber diameter decreased with KCl and ethanol concentration in the coagulation bath. In general, the ultimate tensile stress and elongation at break both increased for KCl concentration from 0.1 to 0.5 M with and without ethanol, with no significant change above 0.5 M. Spinning rate affected the dope flow and thus the polymer orientation (apparent viscosity) and fiber morphology. At spinning rates between 0.25 mL/min and 0.33 mL/min, the fiber diameter reached a minimum and the fiber surface was smooth. Both an increase and decrease from this spinning rate range increased the fiber diameter and roughness of the fiber surface. Post-spinning drawing of the fiber resulted in even smaller fiber diameter.Item Fabrication of pure starch fibers by electrospinning(Elsevier, 2014-05) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaMany efforts to spin starch fibers are reported in the patent and research literature. All reported spinning methods are dependent upon addition of non-starch components, e. g. other polymers, plasticizers or cross-linkers. In the present study, we demonstrate a method of producing pure starch fibers by an electrospinning technique. This method involves choosing an appropriate solvent for native high amylose starch and spinning on a modified electrospinning setup. Resulting starch fibers have diameters in the order of microns. Coagulation solvent composition can affect the crystallinity of the starch fibers. Post-spinning treatments were employed to increase the crystallinity and cross-link the starch fibers. The novel starch fibers have potential in various applications, e. g. in the food, textile, and biomedical industries. (c) 2013 Elsevier Ltd. All rights reserved.Item Formation of starch-guest inclusion complexes in electrospun starch fibers(Elsevier, 2014-07) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaWe have demonstrated a method of fabricating starch fibers with an average diameter in the order of micrometers. In the present study, the formation of starch-guest inclusion complexes in the electrospun starch fibers was evaluated. Two methods were used to electrospin starch fibers with starch-guest inclusion complexes: a dope mixing method, where guest material was mixed into the starch dispersion prior to electrospinning, and a bath mixing method, where guest material was mixed into the coagulation bath into which starch dispersions were electrospun. Three selected guest compounds, palmitic acid, ascorbyl palmitate, and cetyl-trimethylammonium bromide, formed inclusion complexes with starch in the electrospun starch fibers. The presence of native lipids was not necessary to induce the inclusion complex formation. Encapsulation of these molecules in electrospun starch fibers may increase their stability during processing and storage, while providing controlled release properties. (C) 2013 Elsevier Ltd. All rights reserved.Item Inclusion complex formation between high amylose corn starch and alkylresorcinols from rye bran(Elsevier, 2018-09-01) Gunenc, Aynur; Kong, Lingyan; Elias, Ryan J.; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaThe formation of high amylose corn starch (HACS)-alkylresorcinol (AR) inclusion complexes was demonstrated using HACS and a crude AR extract from rye bran, and was confirmed by complementary characterization techniques. Inclusion complex was extracted using hot 2-propanol/water (3:1), and thirteen different AR homologs were identified in the 2-propanol/water extract. However, this extraction regime was insufficient to remove all guests from the inclusion complexes, but did result in annealing of the V-type crystallinity, yielding an endotherm with higher onset and peak temperatures and dissociation enthalpy. The remaining guest compounds were recovered by disruption of the inclusion complexes with DMSO followed by liquid-liquid extraction. A total of nine AR homologs were recovered and two saturated long alkyl chain AR homologs (C21:0 and C19:0) were obviously enriched in the complexes compared to the crude AR extract. The formation of HACS-AR inclusion complexes may have the potential to inhibit staling in baked goods.Item Molecular encapsulation of ascorbyl palmitate in preformed V-type starch and amylose(Elsevier, 2014-10-13) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaIn the present study, we introduce a simple method to prepare inclusion complexes by "inserting" guest molecules into preformed "empty" V-type amylose helices. Ascorbyl palmitate (AscP) was used as a model guest material to investigate the effect of solvent environment, complexation temperature, annealing and guest concentration on inclusion complex formation. High complexation temperature was not necessary for encapsulating guest molecules in amylose helices, avoiding thermal degradation of guest compounds. This method would also avoid the wasting of guest materials because uncomplexed guest can be reused. It was found in the study that intermediate ethanol and acetone concentrations (generally 40-60%, v/v) at room temperature were appropriate for the complexation between V-amylose and AscP. Annealing, i.e. heat treatment in ethanol solutions at elevated temperatures (45-70 degrees C), was able to significantly increase the crystallinity of V-amylose and V-starch to as high as 65% and facilitate greater complexation evidenced from higher enthalpies, probably due to more regularly arranged helical cavities in larger crystalline phase. The complexation between V-amylose and AscP was also found to be enhanced with AscP concentration, while the dissociation temperature experienced a slight decrease. (C) 2014 Elsevier Ltd. All rights reserved.Item Plasticization and conglutination improve the tensile strength of electrospun starch fiber mats(Elsevier, 2018-10) Wang, Hui; Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaElectrospun starch fiber mats have many potential applications, but an improvement in their mechanical properties is required to realize them. In the present study, wet-electrospun starch fiber mats were subjected to post-drying conditioning at controlled equilibrium relative humidity and equilibration time. The weight-normalized ultimate tensile strength of starch fiber mats increased significantly with equilibration at relative humidity > 0.75 after 28 days. Morphological observation and X-ray diffraction analysis excluded significant changes in fiber size or crystallinity, and thus we concluded that conglutination brought about by the plasticizing effect of water and observed microscopically was primarily responsible for this mechanical improvement.Item Quantitative relationship between electrospinning parameters and starch fiber diameter(Elsevier, 2013-02-15) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaThe diameter of the starch fibers produced by electrospinning is a key parameter for most potential applications. In this study, a quantitative relationship between fiber diameter and certain electrospinning parameters, i.e. starch concentration, applied voltage, spinning distance and feed rate, was established by empirical modeling using a fractional factorial experimental design in a constrained region. Response surface methodology was employed to analyze the interactions of the electrospinning parameters and predict the direction to minimize and maximize the fiber diameters. (C) 2012 Elsevier Ltd. All rights reserved.Item Rheological aspects in fabricating pullulan fibers by electro-wet-spinning(Elsevier, 2014-07) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaElectro-wet-spinning was used to fabricate continuous nonwoven microscale and nanoscale fibers from pullulan. We investigated the rheological properties of pullulan dispersions using DMSO: water mixtures as solvents with varying compositions. The relationship between electrospinnability and rheological properties were studied. In order to obtain well-formed pullulan fibers, the concentration of pullulan dispersion had to be 1.88-2.25 times the entanglement concentration, depending on DMSO: water ratio in the solvent. Shear viscosity was another important factor. The shear viscosities at 100 s(-1) of electrospinnable pullulan dispersions fell into a range between 0.06 and 2.2 Pa s, regardless of solvent composition. Yet, there may still be other factors governing the fiber size as DMSO concentration changed. Pullulan fibers in the order of hundreds of nanometers to tens of microns were obtained. Increase in DMSO concentration in the solvent generally increased the fiber size and pore size in the electrospun pullulan fiber mat. (C) 2013 Elsevier Ltd. All rights reserved.Item Role of Molecular Entanglements in Starch Fiber Formation by Electrospinning(American Chemical Society, 2012-06-18) Kong, Lingyan; Ziegler, Gregory R.; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; University of Alabama TuscaloosaWe have demonstrated a method of fabricating pure starch fibers with an average diameter in the order of micrometers. In the present study, correlation between the rheological properties of starch dispersions and the electro-spinnability was attempted via the extrapolation of the critical entanglement concentration, which is the boundary between the semidilute unentangled regime and the semidilute entangled regime. Dispersions of high amylose starch containing nominally 80% amylose (Gelose 80) required 1.2-2.7 times the entanglement concentration for effective electrospinning. Besides starch concentration, molecular conformation, and shear viscosity were also of importance in determining the electrospinnability. The rheological properties and electrospinnability of different starches were studied. Hylon VII and Hylon V starches, containing nominally 70 and 50% amylose, respectively, required concentrations of 1.9 and 3.7 times their entanglement concentrations for electrospinning. Only poor fibers were obtained from mung bean starch, which contains about 35% amylose, while starches with even lower amylose contents could not be electrospun.Item Starch-menthol inclusion complex: Structure and release kinetics(Elsevier, 2019-12) Shi, Linfan; Hopfer, Helene; Ziegler, Gregory R.; Kong, Lingyan; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; South China University of Technology; University of Alabama TuscaloosaFlavoring ingredients are often the most expensive ingredients in food formulations, and their stability and release behavior are significant factors for quality and acceptability of food products. Among flavoring compounds, aroma compounds draw a lot of attention in research, as their volatile nature makes their release difficult to control. In the present study, we employed pre-formed V-type starches to molecularly encapsulate an aroma compound, i.e., menthol. We examined high amylose maize starch of six different V-type crystalline structures (containing 6, 7 and 8 glucose units per helical turn), namely V-6, V-7, and V-8-types, to encapsulate menthol and thus, to control the release behavior. Rehydration of V-6a at a relative humidity of 0.75 lead to its conversion to V-6h (V-h), while rehydration had only minor influence on the XRD patterns of anhydrous forms of V-7 and V-8. Successful inclusion complexation was characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and gas chromatography-mass spectrometry (GC-MS). Upon complexation with menthol, the XRD pattern of V-6h shifted to V-7, whereas all other V-subtypes retained their original crystalline structures. An endotherm with peak temperature at ca. 118 degrees C appeared after inclusion complexation, corresponding to the dissociation of starch-menthol inclusion complexes. Endothermic enthalpy, with the exclusion of V-6a, and GC-MS quantification agreed that the total menthol content in inclusion complexes followed the order of V-6h > V-6a > V-7a> "V-7h" > V-8a > "V-8h", with the helices initially of the V-6h-type being the most effective in encapsulating menthol molecules. The controlled release characteristics of the encapsulated aroma compound were investigated in the presence and absence of pancreatic alpha-amylase. The presence of amylase increased both the release rate and the amount of menthol released within 2 h. The release rates were different among samples made from different subtypes, due to their different association mechanisms with menthol, including physical adsorption on the surface of starch or in the amorphous phase, inter-helical entrapment, and intra-helical inclusion complexation. The Higuchi model was fitted to understand the release kinetics and showed that the constant Y for menthol release from different V-type ICs followed the order of "V-8h" > V-8a> "V-7h" > V-6a > V-7a > V-6h.