Gabriella Fioravanti

To combat the growing issue of petroleum plastic waste, alternative bio-based polymers are being developed. Many of these biopolymers are made from bio-derived materials, or are biodegradable, but the most promising polymers fall in both categories. Polyhydroxyalkanoates (PHAs) are one such class of polymers, and poly-3-hydroxybutyrate (P3HB), the most popular PHA, has shown great potential. This study utilized two types of cotton-derived glucose, alongside commercial glucose, as a feedstock for the biosynthesis of P3HB by Cupriavidus necator (also known as Ralstonia eutropha). The fermentation took place in a 2-L bioreactor, showing potential for scale-up. A single-solvent extraction method was created and utilized to reduce process complexity and chemical consumption of the polymer extraction. Both cotton-derived glucoses were shown to produce more P3HB than commercial glucose. The resulting P3HB samples were compared to each other and to the literature based on polymer yield and thermal characteristics. While all samples averaged a smaller yield than seen in the literature (indicating the need for optimization of the bacterial growth and metabolism with a growth curve in our future work), the cotton-derived glucose was shown to yield more P3HB than commercial glucose. Further, cotton-derived P3HB had very similar thermal properties to the commercial glucose-derived P3HB (and to values from the literature) with onset of thermal degradation ranging from 185 °C to 263 °C, cold crystallization temperatures ranging from 24 °C to 28 °C, and melting temperatures ranging from 147 °C to 151 °C. Lastly, all samples were shown to have a similar percentage crystallinity, ranging from 38% to 45%, which is slightly lower than that reported in the literature. P3HB made from cotton-derived glucose was shown to have potential as a scalable, sustainable alternative process.

To combat the growing issue of petroleum plastic waste, alternative bio-based polymers are being developed. Many of these biopolymers are made from bio-derived materials, or are biodegradable, but the most promising polymers fall in both categories. Polyhy-droxyalkanoates (PHAs) are one such class of polymers, and poly-3-hydroxybutyrate (P3HB), the most popular PHA, has shown great potential. A large drawback to large scale use of P3HB is the cost of its production. Production from local waste carbon sources, in largescale bioprocessing equipment, and using less chemically intensive extraction, drastically reduces P3HB’s cost. In America, the cotton industry offers millions of tons of cellulosic waste each year that can be transformed into a glucose solution. This study utilized two types of cotton-derived glucose, alongside commercial glucose, as a feedstock for the biosynthesis of P3HB by Ralstonia eutropha. The fermentation took place in a 2-L bioreactor, showing potential for scale-up, and a single-solvent extraction method was used, reducing chemical consumption. The resulting P3HB samples were compared to each other and to the literature based on polymer yield and thermal characteristics. First, while all samples averaged a smaller yield than seen in literature, the cotton-derived glucose was shown to yield more P3HB than commercial glucose. Further, cotton-derived P3HB had very similar thermal properties to the commercial glucose-derived P3HB. Lastly, all samples were shown to have a similar percent crystallinity, though slightly lower than that seen in literature. P3HB made from cotton-derived glucose was shown to have potential as a scalable, sustainable alternative process.

The pursuit of an environmentally sustainable manufacturing process requires the substitution of less damaging and recyclable solutions for harmful reagents. This study aims to assess the effectiveness of using cellulose microfibrils synthesized via different hydrolysis reactions as reinforcing agents in polyvinyl alcohol (PVA) at varying concentrations. The investigation explores the morphology, thermal properties, and chemical behavior of the cellulose particles. The cellulose microfibrils (CMFs) produced using citric acid exhibited the highest yield and aspect ratio. Notably, particles from organic acids demonstrated greater thermal stability, with oxalic acid-derived particles displaying the maximum thermal degradation temperature. Subsequently, cast films of PVA reinforced with the cellulose microfibrils underwent comprehensive analyses, including Fourier transfer infrared (FTIR) spectroscopy, thermal degradation temperature (T_d), differential scanning calorimetry (DSC), and tensile strength tests. The thermal behavior of cast films experienced notable changes with the addition of cellulose particles, evidenced by increased melting and crystallinity temperatures, along with a rise in the degree of crystallinity. The incorporation of cellulose particles led to a substantial improvement in mechanical properties. Films containing CMF displayed higher Young’s modulus, and the sample incorporating 5% CMF derived from citric acid exhibited the most significant increase in modulus.

The pursuit of an environmentally sustainable manufacturing process advocates for the substitution of harmful reagents for less damaging and recyclable solutions. This study aims to assess the effectiveness of using cellulose microfibrils synthesized via different hydrolysis reactions as reinforcing agents in polyvinyl alcohol (PVA) at varying con-centrations. The investigation explores the morphology, thermal properties, and chemi-cal behavior of the cellulose particles. The cellulose microfibrils (CMF) produced using citric acid exhibited the highest yield and aspect ratio. Notably, particles from organic acids demonstrated greater thermal stability, with oxalic acid-derived particles displaying the maximum thermal degrada-tion temperature. Subsequently, cast films of PVA reinforced with the cellulose microfibrils underwent comprehensive analyses, including Fourier transfer infrared (FTIR) spectroscopy, thermal degradation temperature (Td), differential scanning calorimetry (DSC), and tensile strength tests. The thermal behavior of cast films experienced notable changes with the addition of cellulose particles, evidenced by increased melting and crystallinity temperatures, along with a rise in the degree of crystallinity. The incorporation of cellulose particles led to a substantial improvement in mechanical properties. Films containing CMF dis-played higher Young’s modulus, and the sample incorporating 5% CMF derived from citric acid exhibited the most significant increase in modulus.

The periosteal and endosteal surfaces of mature bone are densely innervated by sensory nerves expressing TrkA, the high-affinity receptor for nerve growth factor (NGF). In previous work, we demonstrated that administration of exogenous NGF significantly increased load-induced bone formation through the activation of Wnt signaling. However, the translational potential of NGF is limited by the induction of substantial mechanical and thermal hyperalgesia in mice and humans. Here, we tested the effect of gambogic amide (GA), a recently identified robust small molecule agonist for TrkA, on hyperalgesia and load-induced bone formation. Behavioral analysis was used to assess pain up to one week after axial forelimb compression. Contrary to our expectations, GA treatment was not associated with diminished use of the loaded forelimb or sensitivity to thermal stimulus. Furthermore, dynamic histomorphometry revealed a significant increase in relative periosteal bone formation rate as compared to vehicle treatment. Additionally, we found that GA treatment was associated with an increase in the number of osteoblasts per bone surface in loaded limbs as well as a significant upregulation of Wnt1, Wnt7b , and Ngf in loaded bones. To determine if these effects were exclusively mediated by NGF-TrkA signaling in sensory nerves, we cultured MC3T3-E1 cells for 7 or 14 days in osteogenic differentiation media containing NGF (50 ng/mL), GA (5, 50, or 500 nM), or vehicle (DMSO). After 7 days of culture, we observed increases in osteoblastic differentiation markers Runx2, Bglap2 , and Sp7 in response to GA, whereas treatment with NGF was not different than vehicle. Only cells treated with the highest dose of GA (500 nM) had significantly impaired cell proliferation. In conclusion, our study indicates GA may be useful for augmenting skeletal adaptation to mechanical forces without inducing hyperalgesia through actions on both sensory nerves and osteoblasts.