Effect of Surface Functionality on the Rheological and Self-Assembly Properties of Chitin and Chitosan Nanocrystals and Use in Biopolymer Films.

Chitin nanocrystals (ChNCs) are unique to all other bio-derived nanomaterials in one aspect: the inherent presence of a nitrogen moiety. By tuning the chemical functionality of this nanomaterial, and thus its charge and hydrogen bonding capacity, one can heavily impact its macroscopic properties such as its rheological and self-assembly characteristics. In this study, two types of ChNCs are made using acid hydrolysis (AH-ChNCs) and oxidative (OX-ChNCs) pathways, unto which deacetylation using a solvent-free procedure is utilized to create chitosan nanocrystals (ChsNCs) of varying degree of deacetylation (DDA). These nanocrystals were then studied for their rheological behavior and liquid crystalline ordering. It was found that with both deacetylation and carboxylation of ChNCs, viscosity continually increased with increasing concentrations from 2 to 8 wt %, contrary to AH-ChNC dispersions in the same range. Interestingly, increasing the amine content of ChNCs was not proportional to the storage modulus, where a peak saturation of amines provided the most stiffness. Conversely, while the introduction of carboxylation increased the elastic modulus of OX-ChNCs by an order of magnitude from that of AH-ChNCs, it was decreased by increasing DDA. Deacetylation and carboxylation both inhibited the formation of a chiral nematic phase. Finally, these series of nanocrystals were incorporated into biodegradable pectin-alginate films as a physical reinforcement, which showed increased tensile strength and Young's modulus values for the films incorporated with ChsNCs. Overall, this study is the first to investigate how surface functionalization of chitin-derived nanocrystals can affect their rheological and liquid crystalline properties and how it augments pectin/alginate films as a physical reinforcement nanofiller.

High-Humidity Shaker Aging to Access Chitin and Cellulose Nanocrystals.

To unlock nature's potential for functional biomaterials, many efforts have been devoted to isolating the nanocrystalline domains within the supramolecular structure of polysaccharides. Yet, low reactivity and yield in aqueous systems along with excessive solvent usage hinders its development. In this report, the first solvent-free pathway to access carboxylated chitin and cellulose nanocrystals with excellent mass balance is described, relying on a new method coined high-humidity shaker aging (HHSA). The method involves a mild grinding of the polysaccharide with ammonium persulfate followed by an aging phase under high-humidity and on a shaker plate. Insights into the mechanism were uncovered, which highlighted the unique role of high humidity to afford a gradual uptake of water by the material up to deliquescence when the reaction is complete. This process was then validated for direct synthesis of nanocrystals from biomass sources including crab and soft wood pulp.

Carboxylated Chitosan Nanocrystals: A Synthetic Route and Application as Superior Support for Gold-Catalyzed Reactions.

In this study, we demonstrate for the first time the fabrication of carboxylated chitosan nanocrystals (ChsNC) with high degree of deacetylation (DDA) at >80% and narrow size distribution. We also studied its application as a sustainable support material for metal-based catalysts. Carboxylated chitin nanocrystals (ChNCs) were initially prepared through partial cleavage of glycosidic bonds in chitin by ammonium persulfate, with concurrent oxidation of chitin C6 primary alcohols to produce carboxylate groups on the surface of the ChNCs. ChsNCs were subsequently prepared using an alkaline deacetylation procedure in the presence of NaBH4 to preserve the nanorod structure of the biomaterial. The resulting nanocrystals feature both carboxyl and amino functional groups. Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy were used to determine the morphology and composition of these carboxylated ChNCs and ChsNCs. Subsequently, we tested the ability of the as-made ChsNCs as a biomass-based catalyst support for Au nanoparticles (NPs) using the 4-nitrophenol reduction and the aldehyde-amine-alkyne (A3) coupling reactions to demonstrate its capabilities in regard to the ones of cellulose nanocrystals (CNCs). In particular, Au NPs over ChsNCs featured the highest turnover frequency (TOF) value for the 4-nitrophenol reduction reported for all Au-based catalysts supported on carbon-based systems. Spectroscopic and imaging techniques confirmed the importance of precisely controlling the redox state of Au as it is being deposited to afford a highly disperse active site on the bionano-support.

Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction.

In this report, chitin and chitosan nanocrystals were used as biomass-based supports for Pd nanoparticles (NPs) used as a heterogeneous catalyst for the Heck coupling reaction. By using a one-pot fabrication method, a Pd salt precursor was directly reduced and deposited onto these nanocrystal catalysts. Characterization of these nanocomposites showed disperse Pd NPs on the surfaces of the chitinous nanocrystals. Heck coupling model reactions revealed full product yield in relatively benign conditions, outcompeting the use of other catalysts supported on biomass-based nanomaterials, including cellulose nanocrystals. These initial results show the potential for using chitinous nanomaterials as effective catalyst supports in cross-coupling reactions.

Physiological responses and exercise preference between the Trikke and the bicycle ergometer.

BACKGROUND/OBJECTIVE: The positive relationship between health benefits or the wellbeing of individuals and their engagement in physical activity is well-documented. Nevertheless, many Americans show no interest or perceive that "exercise is boring" as one of the reasons for not exercising. For these reasons, it is important to promote fun and enjoyment aspects of the activity to motivate people to participate in physical activity. The purpose of this study was to examine the physiological responses and the perception of enjoyment between the Trikke and the bicycle ergometer. METHODS: Thirty college students (15 males and 15 females) aged 18-45 years old voluntarily participated in the study and showed up on three occasions. The first session involved a 5-minute instructional video and practice on the Trikke. Participants were then randomized into sessions which involved either riding the Trikke or the bicycle ergometer. Participants of each group performed a 20-minute ride at 75-80% of maximal predicted heart rate. RESULTS: Results of mixed design analysis of variance (ANOVAs) indicated that VO2, energy expenditure, and rate of perceived exertion (RPE) of the participants were significantly (p < 0.001) higher when using the bicycle ergometer than the Trikke, and female participants were able to manipulate the Trikke more efficiently than their male counterparts. CONCLUSION: Participants were more efficient in using the Trikke than the bicycle ergometer. The Trikke may be an enjoyable alternative for those individuals, particularly women, who have lost interest in traditional forms of exercise.

Designing sustainable circular bioeconomy solutions for the pulse industry: The case of crude pea starch as a substrate for single cell protein production.

Valorization of crude pea starch has become a key focus in the pea industry's sustainability pursuit. This study aimed to explore the circularity potential of crude pea starch as a nutrient-dense substrate for the solid-state cultivation of yeast (Saccharomyces cerevisiae) Single Cell Protein (SCP). Following the ISO 2006:14040/44 standard, a life cycle assessment (LCA) was performed to ascertain the environmental performance and operational dynamics of baseline and scenario pea starch-based yeast SCP process designs and identify optimal design considerations. Results demonstrated a higher relative contribution to the toxicity categories, with a relatively less contribution to global warming and land use. The distribution and media enrichment processes were identified as the hotspots, contributing about 32-55 % and 40-56 % to global warming and land use, respectively. Generally, train and air freight were more sustainable than lorry freight, respective of mileage and mass. Regarding system alteration, eliminating the media enrichment process could offset about 26 % of land footprint, with a similar trend for most impact categories. Process benchmarking showed up to a 3-fold reduction in global warming impacts relative to soybean meal, and about 71 % offset relative to fishmeal. Consequential LCA showed a general sustainability preference for substituting the aquacultural feeds with pea starch-based SCP, with a stronger emphasis on fishmeal substitution. Overall, these findings highlight the potential of the proposed SCP design as a sustainable upcycling solution with substitutionary potentials for conventional food and feeds, recommending further exploration in value and wealth creation.

Recent advances in cellulose nanocrystals-based antimicrobial agents.

Over the past five years, there has been growing interest in the design of modified cellulose nanocrystals (CNCs) as nanoscale antimicrobial agents in potential end-user applications such as food preservation/packaging, additive manufacturing, biomedical and water purification. The interest of applying CNCs-based antimicrobial agents arise due to their abilities to be derived from renewable bioresources and their excellent physicochemical properties including rod-like morphologies, large specific surface area, low toxicity, biocompatibility, biodegradability and sustainability. The presence of ample surface hydroxyl groups further allows easy chemical surface modifications for the design of advanced functional CNCs-based antimicrobial materials. Furthermore, CNCs are used to support antimicrobial agents that are subjected to instability issues. The current review summarizes recent progress in CNC-inorganic hybrid-based materials (Ag and Zn nanoparticles, other metal/metal oxide) and CNC-organic hybrid-based materials (polymers, chitosan, simple organic molecules). It focuses on their design, syntheses and applications with a brief discussion on their probable modes of antimicrobial action whereby the roles of CNCs and/or the antimicrobial agents are highlighted.

Exploring the functional attributes and in vitro starch and protein digestibility of pea flours having a wide range of amylose content.

In this study, ten pea flours covering a broad range of amylose content (37.2-77.6 %, dsb) were characterized for functional and nutritional properties. As the amylose contents increased, the starch contents of the pea flours showed a downward trend (r = -0.990, p < 0.001 in Pearson correlation) but their protein and total dietary fiber contents exhibited an upward trend (r = 0.915, p < 0.001 and r = 0.885, p < 0.001, respectively). A greater amylose content tended to increase starch gelatinization temperatures of the pea flours, which thus required a higher cooking temperature for pasting viscosity development and subsequent gel formation. An increased amylose level reduced in vitro starch digestibility of the cooked pea flours (r = -0.944, p < 0.001) but did not influence in vitro protein digestibility. The insightful findings will be valuable for utilizing the diverse pea lines to create new flour, starch, and protein ingredients.

Improving Safety Performance of Construction Workers through Learning from Incidents.

Learning from incidents (LFI) is a process to seek, analyse, and disseminate the severity and causes of incidents, and take corrective measures to prevent the recurrence of similar events. However, the effects of LFI on the learner's safety performance remain unexplored. This study aimed to identify the effects of the major LFI factors on the safety performance of workers. A questionnaire survey was administered among 210 construction workers in China. A factor analysis was conducted to reveal the underlying LFI factors. A stepwise multiple linear regression was performed to analyse the relationship between the underlying LFI factors and safety performance. A Bayesian Network (BN) was further modelled to identify the probabilistic relational network between the underlying LFI factors and safety performance. The results of BN modelling showed that all the underlying factors were important to improve the safety performance of construction workers. Additionally, sensitivity analysis revealed that the two underlying factors-information sharing and utilization and management commitment-had the largest effects on improving workers' safety performance. The proposed BN also helped find out the most efficient strategy to improve workers' safety performance. This research may serve as a useful guide for better implementation of LFI practices in the construction sector.

Carboxylated Cellulose Nanocrystals Decorated with Varying Molecular Weights of Poly(diallyldimethylammonium chloride) as Sustainable Antibacterial Agents.

Cationic nanomaterials are promising candidates for the development of effective antibacterial agents by taking advantage of the nanoscale effects as well as other exceptional physicochemical properties of nanomaterials. In this study, carboxylated cellulose nanocrystals (cCNCs) derived from softwood pulp were coated with cationic poly(diallyldimethylammonium chloride) of varying molecular weights. The resulting cationic carboxylated cellulose nanocrystals coated with poly(diallyldimethylammonium chloride) (cCNCs-PDDA) nanomaterials were characterized for their structural and morphological properties using Fourier transform infrared spectroscopy, dynamic light scattering, zeta potential, elemental analysis, transmission electron microscopy, and thermogravimetric analysis. Cationic cCNCs-PDDA were investigated for their antibacterial properties against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli 23934 and Pseudomonas aeruginosa using a bacterial lawn growth inhibition assay. cCNC-PDDA materials displayed marked antibacterial activity, particularly against Gram-positive Staphylococcus aureus. Overall, our results indicated that cCNCs-PDDA could be a potential candidate for antibacterial applications such as antibacterial surfaces or coatings.

Characterization of Virulent T4-Like Acinetobacter baumannii Bacteriophages DLP1 and DLP2.

The world is currently facing a global health crisis due to the rapid increase in antimicrobial-resistant bacterial infections. One of the most concerning pathogens is Acinetobacter baumannii, which is listed as a Priority 1 pathogen by the World Health Organization. This Gram-negative bacterium has many intrinsic antibiotic resistance mechanisms and the ability to quickly acquire new resistance determinants from its environment. A limited number of effective antibiotics against this pathogen complicates the treatment of A. baumannii infections. A potential treatment option that is rapidly gaining interest is "phage therapy", or the clinical application of bacteriophages to selectively kill bacteria. The myoviruses DLP1 and DLP2 (vB_AbaM-DLP_1 and vB_AbaM-DLP_2, respectively) were isolated from sewage samples using a capsule minus variant of A. baumannii strain AB5075. Host range analysis of these phages against 107 A. baumannii strains shows a limited host range, infecting 15 and 21 for phages DLP1 and DLP2, respectively. Phage DLP1 has a large burst size of 239 PFU/cell, a latency period of 20 min, and virulence index of 0.93. In contrast, DLP2 has a smaller burst size of 24 PFU/cell, a latency period of 20 min, and virulence index of 0.86. Both phages show potential for use as therapeutics to combat A. baumannii infections.

Sulfated Lactosyl Archaeol Archaeosome-Adjuvanted Vaccine Formulations Targeting Rabbit Hemorrhagic Disease Virus Are Immunogenic and Efficacious.

Vaccines play an important role in maintaining human and animal health worldwide. There is continued demand for effective and safe adjuvants capable of enhancing antigen-specific responses to a target pathogen. Rabbit hemorrhagic disease virus (RHDV) is a highly contagious calicivirus that often induces high mortality rates in rabbits. Herein, we evaluated the activity of an experimental sulfated lactosyl archaeol (SLA) archaeosome adjuvant when incorporated in subunit vaccine formulations targeting RHDV. The subunit antigens consisted of RHDV-CRM197 peptide conjugates or recombinant RHDV2 VP60. SLA was able to enhance antigen-specific antibody titers and cellular responses in mice and rabbits. Three weeks following immunization, antigen-specific antibody levels in rabbits vaccinated with RHDV2 VP60 + SLA were significantly higher than those immunized with antigen alone, with geomean titers of 7393 vs. 117. In addition, the SLA-adjuvanted VP60-based formulations were highly efficacious in a rabbit RHDV2 challenge model with up to 87.5% animals surviving the viral challenge. These findings demonstrate the potential utility of SLA adjuvants in veterinary applications and highlight its activity in different types of mammalian species.

Starch modification for non-food, industrial applications: Market intelligence and critical review.

The consumer demand for starch continues to grow to meet food consumption needs. However, starch producers are increasingly looking towards non-food, industrial applications to access new markets for revenue generation, while aiming for whole crop utilization to meet sustainability metrics. Native starch properties limit its utilization in many industrial applications, therefore, it is modified through different chemical, enzymatic, and physical processes. This review examines innovation in starch transformation processes, and how modified starch and its functional properties can be used in industrial applications beyond the traditional sectors of textiles and papermaking. Currently, the market value of modified starch is 2.7× greater than native starch and is anticipated to increase through next-generation applications (e.g. packaging, energy and regenerative medicine) enabled by emerging technologies in 3D printing and nanotechnology. Opportunities for increasing the use of other botanical starch sources besides industry-leading corn are also presented through the lens of global market trends.

Mechanochemical Transformations of Biomass into Functional Materials.

Biomass is one of the promising alternatives to petroleum-derived materials and plays a major role in our fight against climate change by providing renewable sources of chemicals and materials. Owing to its chemical and structural complexity, the transformation of biomass into value-added products requires a profound understanding of its composition at different scales and innovative methods such as combining physical and chemical processes. In this context, the use of mechanochemistry in biomass valorization is currently growing owing to its potentials as an efficient, sustainable, and environmentally friendly approach. This review highlights the latest advances in the transformation of biomass (i. e., chitin, cellulose, hemicellulose, lignin, and starch) to functional materials using mechanochemical-assisted methods. We focused here on the methodology of biomass processing, influencing factors, and resulting properties with an emphasis on achieving functional materials rather than breaking down the biopolymer chains into smaller molecules. Opportunities and limitations associated this methodology were discussed accordingly for future directions.

Effect of Chiral Purity on Adjuvanticity of Archaeol-Based Glycolipids.

Archaeosomes composed of sulfated lactosyl archaeol (SLA) glycolipids from stereoisomerically pure archaeol (1) are vaccine adjuvants that can boost immunogenicity and vaccine efficacy in preclinical models. Herein, we report a new synthesis of 2,3-bis((3,7,11,15-tetramethylhexadecyl)oxy) propan-1-ol (3) by treating (±)-3-benzyloxy-1,2-propanediol with a mesylated phytol derivative through a double nucleophilic substitution reaction, followed by reductive debenzylation. Three SLA archaeosomes from archaeols of different chiral purities were prepared, and the effect of stereochemistry on their adjuvanticity toward ovalbumin was investigated. It was found that all SLA archaeosomes induced strong humoral and cell-mediated antigen-specific immune responses following immunization of C57BL/6NCrl mice, with no significant differences, irrespective of the chiral purities. The responses were comparable or better than those obtained using mimetics of approved adjuvants. The performance of SLA archaeosomes during immunization and their lack of dependence on the stereochemistry of archaeol points toward a promising, safe, scalable, and economically viable vaccine adjuvant system.

Controlled tough bioadhesion mediated by ultrasound.

Tough bioadhesion has important implications in engineering and medicine but remains challenging to form and control. We report an ultrasound (US)-mediated strategy to achieve tough bioadhesion with controllability and fatigue resistance. Without chemical reaction, the US can amplify the adhesion energy and interfacial fatigue threshold between hydrogels and porcine skin by up to 100 and 10 times. Combined experiments and theoretical modeling suggest that the key mechanism is US-induced cavitation, which propels and immobilizes anchoring primers into tissues with mitigated barrier effects. Our strategy achieves spatial patterning of tough bioadhesion, on-demand detachment, and transdermal drug delivery. This work expands the material repertoire for tough bioadhesion and enables bioadhesive technologies with high-level controllability.

Immunogenicity of SARS-CoV-2 spike antigens derived from Beta & Delta variants of concern.

Using our strongly immunogenic SmT1 SARS-CoV-2 spike antigen platform, we developed antigens based on the Beta & Delta variants of concern (VOC). These antigens elicited higher neutralizing antibody activity to the corresponding variant than comparable vaccine formulations based on the original reference strain, while a multivalent vaccine generated cross-neutralizing activity in all three variants. This suggests that while current vaccines may be effective at reducing severe disease to existing VOC, variant-specific antigens, whether in a mono- or multivalent vaccine, may be required to induce optimal immune responses and reduce infection against arising variants.

Preparation and Surface Functionalization of Carboxylated Cellulose Nanocrystals.

In recent years, cellulose nanocrystals (CNCs) have emerged as a leading biomass-based nanomaterial owing to their unique functional properties and sustainable resourcing. Sulfated cellulose nanocrystals (sCNCs), produced by sulfuric acid-assisted hydrolysis of cellulose, is currently the predominant form of this class of nanomaterial; its utilization leads the way in terms of CNC commercialization activities and industrial applications. The functional properties, including high crystallinity, colloidal stability, and uniform nanoscale dimensions, can also be attained through carboxylated cellulose nanocrystals (cCNCs). Herein, we review recent progress in methods and feedstock materials for producing cCNCs, describe their functional properties, and discuss the initial successes in their applications. Comparisons are made to sCNCs to highlight some of the inherent advantages that cCNCs may possess in similar applications.

Chitin and chitosan on the nanoscale.

In a matter of decades, nanomaterials from biomass, exemplified by nanocellulose, have rapidly transitioned from once being a subject of curiosity to an area of fervent research and development, now reaching the stages of commercialization and industrial relevance. Nanoscale chitin and chitosan, on the other hand, have only recently begun to raise interest. Attractive features such as excellent biocompatibility, antibacterial activity, immunogenicity, as well as the tuneable handles of their acetylamide (chitin) or primary amino (chitosan) functionalities indeed display promise in areas such as biomedical devices, catalysis, therapeutics, and more. Herein, we review recent progress in the fabrication and development of these bio-nanomaterials, describe in detail their properties, and discuss the initial successes in their applications. Comparisons are made to the dominant nanocelluose to highlight some of the inherent advantages that nanochitin and nanochitosan may possess in similar application.