Preparation, Characterization and Gelation of a Fungal Nano Chitin Derived from Hericium erinaceus Residue

Preparation of nanochitin using deep eutectic solvents

Chitin is an abundant and renewable non-wood biopolymer. Nanochitin is formed by the assembly of chitin molecules, which has the advantages of large tensile strength, high specific surface area, and biodegradability, so it has been widely used. However, the traditional methods of preparing nanochitin have many drawbacks. As the new generation of green solvents, deep eutectic solvents (DESs) have been successfully applied in the fields of chitin dissolution, extraction, and nanochitin preparation. In this review, the relevant knowledge of chitin, nanochitin, and DESs was first introduced. Then, the application status of DESs in the fields of chitin was summarized, with a focus on the preparation of nanochitin using DESs. In conclusion, this review provided a comprehensive analysis of the published literature and proposed insights and development trends in the field of preparation of nanochitin using DESs, aiming to provide guidance and assistance for future researchers.

Hybrid Amyloid-Chitin Nanofibrils for Magnetic and Catalytic Aerogels

In the quest for a sustainable and circular economy, it is essential to explore environmentally friendly alternatives to traditional petroleum-based materials. A promising pathway toward this goal lies in the leveraging of biopolymers derived from food waste, such as proteins and polysaccharides, to develop advanced sustainable materials. Here, we design versatile hybrid materials by hybridizing amyloid nanofibrils derived by self-assembly of whey, a dairy byproduct, with chitin nanofibrils exfoliated from the two distinct allomorphs of α-chitin and β-chitin, extracted from seafood waste. Various hydrogels and aerogels were developed via the hybridization and reassembly of these biopolymeric nanobuilding blocks, and they were further magnetized upon biomineralization with iron nanoparticles. The pH-phase diagram highlights the significant role of electrostatic interactions in gel formation, between positively charged amyloid fibrils and negatively charged chitin nanofibrils. Hybrid magnetic aerogels exhibit a ferromagnetic response characterized by a low coercivity (<50 Oe) and a high specific magnetization (>40 emu/g) at all temperatures, making them particularly suitable for superparamagnetic applications. Additionally, these aerogels exhibit a distinct magnetic transition, featuring a higher blocking temperature (200 K) compared to previously reported similar nanoparticles (160 K), indicating enhanced magnetic stability at elevated temperatures. Finally, we demonstrate the practical application of these hybrid magnetic materials as catalysts for carbon monoxide oxidation, showcasing their potential in environmental pollution control and highlighting their versatility as catalyst supports.

Optimized high-yield synthesis of chitin nanocrystals from shrimp shell chitin by steam explosion

This study attempted for the first time to prepare chitin nanocrystals (ChNCs) from shrimp shell chitin using steam explosion (SE) method. Response surface methodology (RSM) approach was used to optimize the SE conditions. Optimum SE conditions to acquire a maximum yield of 76.78 % were acid concentration (2.63 N), time (23.70 min), and chitin to acid ratio (1:22). Transmission electron microscopy (TEM) revealed the ChNCs produced by SE had an irregular spherical shape with an average diameter of 55.70 ± 13.12 nm. FTIR spectra showed ChNCs were slightly different than chitin due to a shift in peak positions to higher wavenumber and higher peak intensities. XRD patterns indicated ChNCs were a typical α-chitin structure. Thermal analysis revealed ChNCs were less thermally stable than chitin. Compared to conventional acid hydrolysis, the SE approach described in this study is simple, fast, easy, and requires less acid concentration and acid quantity, making it more scalable and efficient for synthesizing ChNCs. Furthermore, the characteristics of the ChNCs will shed light on the potential industrial uses for the polymer.

Nano-chitin reinforced agarose hydrogels: Effects of nano-chitin addition and acidic gas-phase coagulation

Hydrogels based on natural polymers such as agarose usually show low applicability due to their weak mechanical properties. In this work, we developed a dual cross-linked agarose hydrogel by adding different amounts of TEMPO-oxidized nano-chitin (0-0.2 %) to agarose hydrogel matrices and then physically cross-linked under acidic gas-phase coagulation. The prepared hydrogels were characterized by FTIR, XRD, TGA, and SEM. The effects of nano-chitin addition and acidic gas-phase coagulation on the properties of agarose hydrogels, such as gel strength, swelling degree, rheological properties, and methylene blue (MB) adsorption capacity, were also studied. Structural characterizations confirmed that nano-chitin was successfully introduced into agarose hydrogels. The gel strength, storage modulus, and MB adsorption capacity of agarose hydrogels gradually increased with the increasing nano-chitin addition, whereas the swelling degree decreased. After acidic gas-phase coagulation, agarose/nano-chitin nanocomposite hydrogels exhibited improved gel strength and storage modulus, while the swelling degree and MB adsorption capacity were slightly reduced. The combination of oxidized nano-chitin and acidic gas-phase coagulation is expected to be an effective way to improve the properties of natural polymer hydrogels.

Nano-chitin: Preparation strategies and food biopolymer film reinforcement and applications

Current trends in food packaging systems are toward biodegradable polymer materials, especially the food biopolymer films made from polysaccharides and proteins, but they are limited by mechanical strength and barrier properties. Nano-chitin has great economic value as a highly efficient functional and reinforcing material. The combination of nano-chitin and food biopolymers offers good opportunities to prepare biodegradable packaging films with enhanced physicochemical and functional properties. This review aims to give the latest advances in nano-chitin preparation strategies and its uses in food biopolymer film reinforcement and applications. The first part systematically introduces various preparation methods for nano-chitin, including chitin nanofibers (ChNFs) and chitin nanocrystals (ChNCs). The nano-chitin reinforced biodegradable films based on food biopolymers, such as polysaccharides and proteins, are described in the second part. The last part provides an overview of the current applications of nano-chitin reinforced food biopolymer films in the food industry.

Extraction, quantification, characterization, and application in food packaging of chitin and chitosan from mushroom: A review

The application of chitin in food systems is limited by its insolubility in some common solvents and poor degradability. Hence, it is deacetylated to obtain chitosan, an industrially important derivative with excellent biological properties. Fungal-sourced chitosan is gaining prominence and industrial attraction because of its superior functional and biological properties, and vegan appeal. Further, the absence of such compounds as tropomyosin, myosin light chain, and arginine kinase, which are known to trigger allergic reactions, gives it an edge over marine-sourced chitosan in food and pharmaceutical applications. Mushrooms are macro-fungi with a significant content of chitin, with many authors reporting the highest content to be in the mushroom stalks. This indicates a great potential for the valorisation of a hitherto waste product. Hence, this review was written to provide a global summary of literature reports on the extraction and yield of chitin and chitosan from different fruiting parts of some species of mushroom, different methods used to quantify extracted chitin, as well as physicochemical properties of chitin and chitosan from some mushroom species are presented. Critical comparisons of reports on chitin and chitosan from mushrooms and other sources are made. This report concludes with an exposition of the potential application of mushroom-sourced chitosan for food packaging application. The reports from this review provide a very positive outlook regarding the use of mushrooms as a sustainable source of chitin and chitosan and the subsequent application of chitosan as a functional component in food packaging.

Effective detection of ZnO in nicotine using butterfly wing scales

This study aimed to elucidate the optical functions of naturally butterfly wing scales via precise control of morphology as an effective photonic sensor and confirm the content of metal oxide nanoparticles in surrounding nicotine. Metal oxide nanoparticles mixed with nicotine were deposited on the wing scales through the spin-coating method and hence investigated using optical microscopy and spectroscopy. Experimental results demonstrated that absorption intensities of ZnO and TiO₂ mixed with nicotine on Danaus genutia were remarkably enhanced. Due to the relatively high concentration of zinc found in e-cigarette aerosol, the intensity of ZnO/nicotine modelled as aerosol adsorption on Danaus genutia, further held a certain linear relationship with the concentration of ZnO. The limit of detection of ZnO was as low as 1 nM. The working mechanism of our sensor was explained through the molecular adsorption after H-bond formation of ZnO/nicotine molecules as high-index materials on the wing scales of Danaus genutia without aggregation. This photonic sensor is an alternative to the present-day methods for the rapid test of ZnO content, which is very simple without complicated instrumentation. Furthermore, our method might become a starting point for the advancement of portable instruments for onsite ZnO detection.