Since 1950, there has been an exponential increase in the production of plastic from 2 million to 460 million metric tons produced per year. With this production also comes the exacerbated effects on climate change and health: 2.24 billion metric tons of carbon emitted annually, pollution of ecosystems, and degradation of plastics to microplastics that enter living organisms. There is a clear need to develop eco-friendly plastic alternatives. The Roumeli Research Group has previously observed the ability to form biodegradable plastics (bioplastics) from unprocessed biological matter (biomatter). More specifically, use of whole cells of microalgae spirulina can be processed using conventional plastic manufacturing techniques like hot pressing. My project focuses on understanding the changes in chemical and molecular properties of spirulina that occur during the biomatter to bioplastic transition as a function of processing conditions. I fabricated hundreds of dime-sized samples by hot pressing spirulina powder in customized molds under various temperatures, pressures, and periods of time. I also characterized these samples using Fourier Transform Infrared Spectroscopy (FTIR) to inspect the relationship between chemical bonds and spirulina morphology. I analyze these FTIR results in conjunction with creating and pressing samples of biomatter analogues to better understand spirulina’s complex structure. My efforts, along with other characterization techniques like hardness testing and Scanning Electron Microscopy (SEM), will inform modifications of the processing design to obtain desired mechanical properties of the resulting spirulina bioplastic. These findings can be integrated into a machine learning model that concurrently analyzes multiple characterization results to identify trends in the data and further contribute to our understanding of structure as it relates to pressing conditions. 

The growing demand for sustainable materials has driven research into biodegradable alternatives to petroleum-based plastics. Global plastic production has surged to 367 million metric tons as of 2018, with projections indicating a threefold increase by 2050. The persistence of petroleum-based plastics has led to the accumulation of nearly 5 billion metric tons of plastic waste in oceans and ecosystems since the 1950s, presenting significant environmental challenges. This highlights the need for sustainable alternatives, such as algae-based bioplastics. Photosynthetic algae, such as spirulina, can be processed through hot pressing to produce bioplastics with mechanical properties comparable to conventional plastics. Moreover, algal bioplastics are biodegradable, and algae’s ability to capture atmospheric carbon positions this material as a promising eco-friendly alternative. The chemical composition of algae includes protein, carbohydrates, lipids, as well as vitamins, minerals, and pigments. My research aims to analyze the role of lipids on the formation and performance of the resulting bioplastic. Algae cells were disrupted using mechanical force, followed by lipid extraction using a chloroform-based solvent. The extracted lipids were characterized using Fourier Transform Infrared (FTIR) spectroscopy, revealing consistent peaks associated with lipids. The lipid free algae was then hot pressed to evaluate the mechanical strength of the bioplastic in the absence of lipids. Future work will aim to further analyze the microscopic structure of lipid-free bioplastics to determine the role of lipids in their formation and cohesion. Additionally, this research is expanding to extract other macromolecules, such as proteins and carbohydrates, to investigate their contributions to bioplastic performance. Gaining insight into the roles of lipids and other macromolecules will enable the precise design and optimization of bioplastic materials.

Common drug delivery materials, like poly(lactic-co-glycolic) acid, are sourced from non-renewable resources and involve multi-step processing with harsh organic solvents that require proper waste disposal. A more sustainable material derived from biological sources and abundant in nature is bacterial cellulose (BC). BC requires mild growth conditions, is commercially scalable, and has current drug delivery applications in antimicrobial wound dressings. The aim of this project is to establish a sustainable approach to targeted drug delivery using bacterial cellulose nanoparticles (BCNPs). BCNPs are nano- scale, allowing for sufficient tissue penetration, and have easily modifiable hydroxyl end groups that make them susceptible to incorporation of different drugs among other beneficial interactions. The BCNP modifications to the end group are achieved through substitution with methyl-, acetyl-, or amino- functional groups because these groups allow the use of more hydrophobic or hydrophilic materials due to their molecular interactions. To formulate the modified BCNPs, a BC pellicle was grown in black tea media, isolated and washed. The pellicle undergoes methylation, acetylation, and amination reactions and is characterized through Fourier Transform infrared spectroscopy and contact angle measurements. The unmodified and modified pellicles were chemically and mechanically dissolved, and then nanoprecipitated into surfactant solution to form the BCNPs. After dialysis and size filtering the BCNPs were applied in vitro to BV-2 cells, a microglial cell model, to assess cell death through a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium reduction assay. These preliminary cytotoxicity results support the translation of unmodified and modified BCNPs into ex vivo models to certify a wider range of biocompatibility for BCNPs in targeted drug delivery. 

Stone wool, with its exceptional insulation and fire resistance properties, is an effective material for reducing the energy consumption and environmental impact of buildings. Adhesives such as phenol-formaldehyde resins are used in conventional stone wool systems to provide mechanical strength to the system but require high temperatures and energetic costs during their curing process while also emitting harmful emissions during their uncured and curing phases. Our research aims to develop a non-toxic and fully degradable binder system utilizing algal biomatter, xanthan gum, and bacterial nanocellulose. We investigate the rheological properties of biobinders at different concentrations and evaluate the effects of thermal processing on the mechanical properties of the biobinder. Additionally, we use scanning electron microscopy (SEM) to study the distribution and microstructure of biobinder in the composite systems and Fourier transform infrared (FT-IR) spectroscopy to analyze the bonding interactions between each component at different temperatures. In this work, we obtain a better understanding of the interacting mechanisms between each biopolymer and their effects on biobinder mechanical performance, which shows great potential for reducing the environmental impacts of mineral fiber insulation materials.

Cellulose nanofibres (CNFs), produced from sustainable plant resources, are an emerging class of renewable structural biopolymers. Through surface modification via carboxylation and control of fiber length and aspect ratio, CNFs are open to wider usage through further modification of the carboxylated site. However, an understanding of the foundational specific thermodynamics and kinetics of cellulose defibrillation and surface charge modification has not been developed and generalized, hindering widespread adoption of this biopolymer in applications. Additionally, the current fabrication methods for carboxylated cellulose nanofibers (C-CNFs) require harsh solvents and limit reusability. Thus, this study utilizes a deep eutectic solvent treatment (DES) containing citric acid, oxalic acid, and iron(III) chloride to guide the defibrillation of bacterial cellulose (BC) fibers and their carboxylation. We controlled the ratio of the DES components, normalized by the weight of the BC, and determined the reaction rate of bacterial cellulose carboxylation. Through electron microscopy (EM) and zeta potential analysis of titration results, we determined the morphology and composition of the carboxylated BC and surface charge. This work provides insights into the kinetic and thermodynamic interplay that governs the surface charge modification and defibrillation of bacterial cellulose, offering a foundation for further application.