The development of a facile, reductant- and stabilizer-free alkali-mediated synthesis of gold nanoparticles (AuNPs) within cotton fibers for biocompatible textiles is described in this study. Uses of external chemicals compromises the biocompatibility of AuNPs. Additionally, alkali-mediated synthesis of AuNPs inside cotton has not been successful previously. Herein, AuNPs are synthesized in situ within the interior of cotton fibers under alkaline conditions using a Au(III) (Au3+) precursor (tetrachloroauric acid, HAuCl4) without adding any reducing or capping agents. A mechanism of AuNP formation using cotton cellulose has been studied to understand the formation of Au3+-cellulose complexes and their subsequent reduction to zerovalent atoms. AuNP-infused cotton fibers (AuNP-cotton) were analyzed using ultraviolet-visible (UV-vis) spectroscopy, and the surface plasmon resonance (SPR) peak at 538 nm confirms the reduction of the Au3+ precursor and the formation of metallic AuNP (Au0). The obtained AuNPs are spherical with an average diameter of 12.25 nm. Au content in treated cotton was determined to be 1.66 wt % using graphite furnace atomic absorption spectroscopy (GFAAS). High-resolution electron microscopy techniques reveal the internal formation of AuNPs within the cotton fibers, which are uniformly distributed without agglomeration. The AuNPs incorporated into the cotton fabric demonstrated superior laundering durability under intense mechanical force, retaining 82% AuNPs after 50 home laundering cycles. Rapid and efficient catalytic activity of AuNP-cotton demonstrates easy accessibility of the AuNP surface for chemical interactions across multiple cycles. Notably, nontoxicity toward mouse fibroblast cells and efficient photothermal conversion efficiency (2.3-6.4%) suggest that AuNP-cotton has strong potential to support human cell growth and suitability for biocompatible applications.

Cellulose nanofibril-silver (CNF-Ag) hybrid and ultralight silver-infused aerogel were produced using cotton gin trash (CGT), an abundant agro-waste material. This repurposing of CGT was achieved by exploiting its potential for CNF extraction and the in situ synthesis of silver nanoparticles (Ag NPs). CNFs were extracted from CGT through a mechanical shearing process. These CNFs served as a multifunctional nanotemplate for the controlled reduction of Ag ions, efficient nucleation, and stabilization of NPs, resulting in the production of a high concentration of Ag NPs (ca. 19 wt %) within the CNFs. Transmission electron microscopy images of cross-sectioned CNFs confirmed the uniform dispersion of NPs (ca. 18 nm diameter) inside the CNFs. Rietveld refinement analysis of X-ray diffraction patterns revealed that CNFs produced smaller Ag crystallites compared to CGT microparticles. The CNF-Ag hybrid was then fabricated into an aerogel using freeze-drying, with its weight being light enough to rest on a cotton flower's stamen. The infusion of Ag NPs led to approximately 20% reductions in the specific surface area and pore volume of the aerogel.

In this study, the application of a novel polymer-supported Cu2O/CuO nanoparticle catalyst for the efficient degradation of an organic dye, in which the nanoparticle catalyst is incorporated within a natural plant fiber matrix, is presented. The use of plant fibers provides a renewable and environmentally friendly support material, and enhances the catalytic efficiency over consecutive degradation cycles. This innovative design promotes the efficient adsorption and degradation of dye. The nanoparticle biocomposite showed a remarkable capacity to degrade methyl orange in solution (50 ppm, 150 mL) in <3 h (pH 7.2) or <1.5 h (pH 9.1) using 150 mg catalyst material containing 1.7 wt % copper content. Over five catalytic reaction cycles, the content of Cu1+ relative to Cu2+ increased from 57.6 to 94.1%, average particle size decreased from 54.7 +/- 58.5 to 28.7 +/- 22.0 nm and the average circularity increased from 0.69 +/- 0.25 to 0.75 +/- 0.25, while maintaining high catalytic degradation efficiency (>99.6%). The experimental results demonstrate high degradation rates, showcasing the catalyst's potential for sustainable industrial waste remediation applications.

Inflammatory disease biomarker detection has become a high priority in point-of-care diagnostic research in relation to chronic wounds, with a variety of sensor-based designs becoming available. Herein, two primary aspects of biosensor design are examined: (1) assessment of a cellulose nanofiber (CNF) matrix derived from cotton ginning byproducts as a sensor transducer surface; and (2) assessment of the relation of spacer length and morphology between the CNF cellulose backbone and peptide fluorophore as a function of sensor activity for porcine pancreatic and human neutrophil elastases. X-ray crystallography, specific surface area, and pore size analyses confirmed the suitability of CNF as a matrix for wound care diagnostics. Based upon the normalized degree of substitution, a pegylated-linker connecting CNF transducer substrate to peptide fluorophore showed the greatest fluorescence response, compared to short- and long-chain alkylated linkers.

Anions have a profound effect on the properties of soluble proteins. Such Hofmeister effects have implications in biologics stability, protein aggregation, amyloidogenesis, and crystallization. However, the interplay between the important noncovalent interactions (NCIs) responsible for Hofmeister effects is poorly understood. To contribute to improving this state of affairs, we report on the NCIs between anions and ammonium and guanidinium hosts 1 and 2, and the consequences of these. Specifically, we investigate the properties of cavitands designed to mimic two prime residues for anion-protein NCIs─lysines and arginines─and the solubility consequences of complex formation. Thus, we report NMR and ITC affinity studies, X-ray analysis, MD simulations, and anion-induced critical precipitation concentrations. Our findings emphasize the multitude of NCIs that guanidiniums can form and how this repertoire qualitatively surpasses that of ammoniums. Additionally, our studies demonstrate the ease by which anions can dispense with a fraction of their hydration-shell waters, rearrange those that remain, and form direct NCIs with the hosts. This raises many questions concerning how solvent shell plasticity varies as a function of anion, how the energetics of this impact the different NCIs between anions and ammoniums/guanidiniums, and how this affects the aggregation of solutes at high anion concentrations.

Cotton gin waste presents a significant challenge in the cotton ginning industry due to its abundant generation and limited disposal options. In this study, we explored the potential of cotton gin waste as a naturally occurring source material that can synthesize and host silver nanoparticles. The noncellulosic constituents of cotton gin waste served as effective reducing agents, facilitating the conversion of silver ions into silver atoms, while its porous structure acted as a microreactor, enabling controlled particle growth. A simple heat treatment of cotton gin waste powder in an aqueous silver precursor solution actualized the in situ synthesis of silver nanoparticles, without the need for additional chemical agents. Remarkably, a high concentration of silver nanoparticles (14.7%) with an average diameter of approximately 27 nm was produced throughout the entire volume of cotton gin waste. Electron microscopic images of cross-sectioned cotton gin waste confirm the internal formation of nanoparticles. Rietveld refinement analysis of X-ray diffraction patterns showed that the majority of the nanoparticles possess a cubic silver crystal structure. By leveraging the well-known biocidal properties of silver nanoparticles, the resulting silver nanoparticle-filled cotton gin waste holds promise for novel antimicrobial and antifungal material applications.

Two of the research areas that have gained a lot of current attention are nanotechnology and sustainable green chemistry. It seems attractive to use the methodologies of both areas in carrying out research studies involving polymers and agriculture. The present authors have been actively pursuing this combined approach in their research work, and a selected review is given here that highlights some of the relevant studies. A common thread in these studies is the use of agro-based nanomaterials as key components in various polymeric products. This approach is advantageous because the nanomaterials involved are non-toxic, biodegradable and sustainable, and their incorporation often enhances the end-use performance of the polymeric products. Examples of these studies include biobased wood adhesives, paper strength agents, rheology modifiers, edible films for food packaging, nanocomposites, and fertilizer applications.

Peptide–cellulose conjugates designed for use as optical protease sensors have gained interest for point-of-care (POC) detection. Elevated serine protease levels are often found in patients with chronic illnesses, necessitating optimal biosensor design for POC assessment. Nanocellulose provides a platform for protease sensors as a transducer surface, and the employment of nanocellulose in this capacity combines its biocompatibility and high specific surface area properties to confer sensitive detection of dilute biomarkers. However, a basic understanding of the spatiotemporal relationships of the transducer surface and sensor disposition is needed to improve protease sensor design and development. Here, we examine a tripeptide, fluorogenic elastase biosensor attached to TEMPO-oxidized nanofibrillated cellulose via a polyethylene glycol linker. The synthetic conjugate was found to be active in the presence of human neutrophil elastase at levels comparable to other cellulose-based biosensors. Computational models examined the relationship of the sensor molecule to the transducer surface. The results illustrate differences in two crystallite transducer surfaces ((110) vs. (1−10)) and reveal preferred orientations of the sensor. Finally, a determination of the relative (110) vs. (1−10) orientations of crystals extracted from cotton demonstrates a preference for the (1−10) conformer. This model study potentiates the HNE sensor results for enhanced sensor activity design.

There is current interest in replacing petroleum-based additives in consumer paper products with abundantly available, renewable and sustainable biopolymers such as lignin-containing cellulose nanofibers (LCNFs) and cottonseed protein. This research characterized the performance of cottonseed protein isolate with/without LCNFs to increase the dry strength of filter paper. The application of 10% protein solution with 2% LCNFs as an additive improved the elongation at break, tensile strength and modulus of treated paper products compared to the improved performance of cottonseed protein alone. Improvements in tensile modulus and tensile strength were greatest for samples containing larger amounts of lignin and a greater degree of polymerization than for those with less lignin from the same biomass sources.

Here we describe the synthesis and characterization of a peptide-cellulose conjugate biosensor based on TEMPO-oxidized nanofibrillated cellulose (tNFC) for detecting elevated levels of human neutrophil elastase (HNE) in chronic wounds. The fluorescent peptide HNE substrate constructed from n-succinyl-Ala-Pro-Ala-7-amino-4-methyl-coumarin was attached to the TEMPO-oxidized cellulose surface via polyethylene glycol linker. The characterization of the biosensor conjugate shows a high degree of peptide incorporation onto the surface with the degree of substitution of 0.057. The relatively small crystallite size of 26.0 Å compared to other cellulose- and nanocellulose-based materials leads to a large specific surface area which can promote access of HNE to the enzyme substrates due to decreased steric interactions. Likewise, the porosity for tNFC was found to be higher than all other samples, including the nanocellulosic aerogel, lending to its hydrogel-like nature. The properties of tNFC were compared to other cellulose-based materials. The volume of each crystallite and volume ratio to the largest sample was calculated. tNFC was found to occupy the smallest space resulting in high amounts of sensors per crystallite unit volume. With a small crystallite volume and large number of sensors, the tNFC peptide-cellulose conjugate biosensor could provide a more sensitive system and is a good candidate for point of care diagnostic devices for detecting elevated protease levels in humans.

Azo dyes are commonly used in textile color processing for their wide array of vibrant colors. However, in recent years these dyes have become of concern in wastewater management given their toxicity to humans and the environment. In the present work, researchers remediated water contaminated with azo dyes using silver nanoparticles (Ag NPs) intercalated within cotton fabric as a catalyst, for their enhanced durability and reusability, in a reductive degradation method. Three azo dyes—methyl orange (MO), Congo red (CR), and Chicago Sky Blue 6B (CSBB)—were investigated. The azo degradation was monitored by UV/vis spectroscopy, degradation capacity, and turnover frequency (TOF). The Ag NP–cotton catalyst exhibited excellent degradation capacity for the dyes, i.e., MO (96.4% in 30 min), CR (96.5% in 18.5 min), and CSBB (99.8% in 21 min), with TOFs of 0.046 min−1, 0.082 min−1, and 0.056 min−1, respectively, using a 400 mg loading of catalyst for 100 mL of 25 mg L−1 dye. To keep their high reusability while maintaining high catalytic efficiency of >95% degradation after 10 cycles, Ag NPs immobilized within cotton fabric have promising potential as eco-friendly bio-embedded catalysts.

Cotton gin motes (CGM) and cotton gin trash (CGT) are abundant, renewable, low-value agricultural by-products that are excellent feedstocks for the production of cellulose nanocrystals (CNCs). In the following, process methods to obtain CNCs from CGM and CGT are discussed in light of previously published methods. Process method selection is most influenced by the specific physical property demands of the CNC product as a composite material.

A simple method was developed to deposit palladium (Pd) nanoparticles (NPs) within an inexpensive substrate, nonwoven brown cotton fabric, using naturally occurring polyphenols contained within the fabric as a reducing agent. The Pd NPs were imbedded within the fiber's cross-sectional area. The Pd-impregnated substrate was applicable in a series of Suzuki-Miyaura cross-coupling reactions, wherein the product yields were affected by steric hindrance and aryl halide selection; para-substituted and iodoaryl reactants provided the greatest yields. The Pd NPs were catalytically active at submilliequivalent levels, retained catalytic activity for 10 experimental cycles, and did not leach into isolated products.

Bisphenol-substituted spirocyclic phosphazene derivatives were synthesized in 85%–94% yields and analyzed for flame retardant application to cotton fabric using Limiting Oxygen Index, Fourier transform infrared thermogravimetric analysis, differential scanning calorimetry, microscale combustion calorimetry, thermogravimetric analysis, and scanning electron microscopy. The thermogravimetric analysis methods indicate a decomposition pathway consistent for phosphorus-nitrogen-containing compounds. Levoglucosan phosphorylation and carbonaceous char formation were observed. Limiting Oxygen Index testing of these compounds on cotton-based fabrics showed improved flame resistance compared to untreated fabrics.

The use of agricultural waste and residues in composite materials is a potential high-value commercial application for underutilized renewable resources and provides alternative commercial markets to the agricultural industry. Cotton gin trash (CGT) and cotton gin motes (CGM) are underutilized low-value commodities that are attractive targets due to their high cellulose content; however, each contains various amounts of lignin, hemicellulose and other components that impede their utilization as commercial products. In this work, lignin-containing cellulose nanofibers (LCNFs) with gradient degrees of lignin content were prepared from CGT and CGM. Analyses showed the lignin content and other components affected the physical properties of LCNFs, modestly altering their thermal stability and crystallinity. The degree of polymerization (DP) was smaller after successive rounds of processing and was also dependent upon the source (CGT or CGM) with CGT providing nanofibers with a smaller DP than CGM. This translated into slightly different suspension viscoelastic behavior as determined by rheological measurements. Graphic abstract

The preparation of cellulose nanocrystals (CNCs) from cellulose extracted from cotton gin motes (CGM) using an ionic liquid (1-butyl-3-methylimidazolium chloride, [BMIm]Cl) under dilute conditions is reported. The concurrent process involves minimal swelling of cellulose with an ionic liquid and hydrolysis of the cellulose initiated by the addition of either phosphoric (H3PO4), hydrochloric (HCl), or sulfuric (H2SO4) acid. The obtained nanocrystals had similar physical properties (e.g. crystallinity) to the counterparts prepared under conventional conditions and exhibited superior thermal properties for sulfate CNCs. Additionally, the obtained CNCs had low surface functionalization, yet were colloidally stable for >90 days, which is a desirable trait for post-functionalization of CNCs. This process represents a general strategy utilizing dilute ionic liquids in the preparation of nanocellulose under mildly acidic conditions.

Cellulose nanocrystals (CNC) have attracted a great deal of attention as an environmentally-friendly biorenewable resource for use as reinforcing agents in nanocomposites, polymers, gels, and emulsions. CNCs are typically prepared from extracted cellulose or highly refined cellulose products. The chemical refining process can alter the chemical and physical properties of the cellulose fibers prior to extraction of CNCs. Moreover, the method of isolation can also insert various functional groups onto the nanocellulose, affecting thermal stability and imparting different physical properties. Herein, two byproducts of the cotton industry, cotton gin motes and cotton gin waste, are investigated for the preparation of nanocelluloses. Cellulose was purified from these two post-process agroindustrial by-products and CNCs subsequently produced by sulfuric acid hydrolysis. Additionally, two acid hydrolysis methods were utilized to successfully extract CNCs from gin motes without chemical pretreatment. CNCs were obtained with diameters < 10 nm and lengths of ca. 100–300 nm resulting in high aspect ratios (12–33). Incorporating CNCs with these dimensions impart increased hydrophilicity to a substrate. The effect of post-extraction chemical treatments on crystallinity and morphology are discussed. The extracted nanocellulose derivatives were additionally characterized by FTIR, AFM, TGA, DLS, XRD and XPS. Differences in extraction method and chemical treatment resulted in different thermal properties and colloidal stability. Furthermore, this work provides a means of producing a high value commodity from inexpensive source materials such as cotton gin motes and cotton gin waste.

Nonwoven fabrics have grown in popularity in recent years due to their overwhelming usage in a wide range of consumer products. Cotton-based nonwovens are of particular interest because of their ability to be recycled and reused, resulting in a more environmentally friendly product compared to their petroleum-based counterparts. The current research characterized the use of cottonseed protein as an additive to increase the dry strength of cotton-based nonwovens. The tensile strength of nonwovens was found to increase as the concentration of protein applied was increased. At 11% protein concentration, the tear strength and burst strength increased significantly (relative to the nonwoven by itself) by 288% (machine direction) and 295%, respectively. Further characterization by thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy suggested that cottonseed protein interacted with the cotton fiber in the nonwoven fabric to produce the increased dry strength.