Polysaccharide-dextrin thickened fluids for individuals with dysphagia: recent advances in flow behaviors and swallowing assessment methods.

The global aging population has brought about a pressing health concern: dysphagia. To effectively address this issue, we must develop specialized diets, such as thickened fluids made with polysaccharide-dextrin (e.g., water, milk, juices, and soups), which are crucial for managing swallowing-related problems like aspiration and choking for people with dysphagia. Understanding the flow behaviors of these thickened fluids is paramount, and it enables us to establish methods for evaluating their suitability for individuals with dysphagia. This review focuses on the shear and extensional flow properties (e.g., viscosity, yield stress, and viscoelasticity) and tribology (e.g., coefficient of friction) of polysaccharide-dextrin-based thickened fluids and highlights how dextrin inclusion influences fluid flow behaviors considering molecular interactions and chain dynamics. The flow behaviors can be integrated into the development of diverse evaluation methods that assess aspects such as flow velocity, risk of aspiration, and remaining fluid volume. In this context, the key in-vivo (e.g., clinical examination and animal model), in-vitro (e.g., the Cambridge Throat), and in-silico (e.g., Hamiltonian moving particles semi-implicit) evaluation methods are summarized. In addition, we explore the potential for establishing realistic assessment methods to evaluate the swallowing performance of thickened fluids, offering promising prospects for the future.

Fabrication and characterization of complex coacervates utilizing gelatin and carboxymethyl starch.

BACKGROUND: Modified polysaccharides have greatly expanded applications in comparison with native polysaccharides due to their improved compatibility and interactions with proteins and active compounds in food-related areas. Nonetheless, there is a noticeable dearth of research concerning the utilization of carboxymethyl starch (CMS) as a microcapsule wall material in food processing, despite its common use in pharmaceutical delivery. The development of an economical and safe embedding carrier using CMS and gelatin (GE) holds immense importance within the food-processing industry. In this work, the potential of innovative coacervates formed by the combination of GE and CMS as a reliable, stable, and biodegradable embedding carrier is evaluated by turbidity measurements, thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and rheological measurements. RESULTS: The results indicate that GE-CMS coacervates primarily resulted from electrostatic interactions and hydrogen bonding. The optimal coacervation was observed at pH 4.6 and with a GE/CMS blend ratio of 3:1 (w/w). However, the addition of NaCl reduced coacervation and made it less sensitive to temperature changes (35-55 °C). In comparison with individual GE or CMS, the coacervates exhibited higher thermal stability, as shown by TGA. X-ray diffraction analysis shows that the GE-CMS coacervates maintained an amorphous structure. Rheological testing reveals that the GE-CMS coacervates exhibited shear-thinning behavior and gel-like properties. CONCLUSION: Overall, attaining electroneutrality in the mixture boosts the formation of a denser structure and enhances rheological properties, leading to promising applications in food, biomaterials, cosmetics, and pharmaceutical products. © 2023 Society of Chemical Industry.

Transparent and iridescent photonic films with intelligent responsive ability based on electrospun core-shell nanofibrous membranes.

The fabrication of transparent and iridescent photonic films that possess intelligent responsiveness by membrane electrospinning is challenging due to the lack of periodic changes in the refractive index (RI) of electrospun membranes. Herein, transparent and iridescent photonic films are prepared through electrospinning core-shell polyacrylonitrile/glucose-containing polyvinyl alcohol (PAN/PVA@GLU) membranes, infiltrated with a cellulose nanocrystal/polyvinyl alcohol/glucose (CNC/PVA/GLU) suspension, followed by evaporation-induced co-assembling. The as-prepared transparent and iridescent photonic films exhibited reversible changes in selective reflection wavelengths ranging from the visible light to the near-infrared region in response to alternate changes in the relative humidity (RH). Thus, the films could be used as an alcohol dipstick by choosing solvents with different polarities such as alcohol-water mixtures of different ratios. Moreover, the films were highly deformable with a strain at failure up to 14.91% without a compromise of strength. In sum, the current work demonstrates a strategy for the design and fabrication of transparent and iridescent photonic films with intelligent responsiveness using electrospinning, and a soft material platform for developing scalable colorimetric sensors and optically active components.

Adhesive and Flame-Retardant Properties of Starch/Ca2+ Gels with Different Amylose Contents.

Starch, being renewable and biodegradable, is a viable resource for developing sustainable and environmentally friendly materials. The potential of starch/Ca2+ gels based on waxy corn starch (WCS), normal corn starch (NCS), and two high-amylose corn starches, G50 (55% amylose content) and G70 (68% amylose content) as flame-retardant adhesives has been explored. Being stored at 57% relative humidity (RH) for up to 30 days, the G50/Ca2+ and G70/Ca2+ gels were stable without water absorption or retrogradation. The starch gels with increasing amylose content displayed increased cohesion, as reflected by significantly higher tensile strength and fracture energy. All the four starch-based gels showed good adhesive properties on corrugated paper. For wooden boards, because of the slow diffusion of the gels, the adhesive abilities are weak initially but improve with storage extension. After storage, the adhesive abilities of the starch-based gels are essentially unchanged except for G70/Ca2+, which peels from a wood surface. Moreover, all the starch/Ca2+ gels exhibited excellent flame retardancy with limiting oxygen index (LOI) values all around 60. A facile method for the preparation of starch-based flame-retardant adhesives simply by gelating starch with a CaCl2 solution, which can be used in paper or wood products, has been demonstrated.

Wheat Flour-Based Edible Films: Effect of Gluten on the Rheological Properties, Structure, and Film Characteristics.

This work investigates the structure, rheological properties, and film performance of wheat flour hydrocolloids and their comparison with that of a wheat starch (WS)-gluten blend system. The incorporation of gluten could decrease inter-chain hydrogen bonding of starch, thereby reducing the viscosity and solid-like behavior of the film-forming solution and improving the frequency-dependence, but reducing the surface smoothness, compactness, water vapor barrier performance, and mechanical properties of the films. However, good compatibility between starch and gluten could improve the density of self-similar structure, the processability of the film-forming solution, and film performance. The films based on wheat flours showed a denser film structure, better mechanical properties, and thermal stability that was no worse than that based on WS-gluten blends. The knowledge gained from this study could provide guidance to the development of other flour-based edible packaging materials, thereby promoting energy conservation and environmental protection.

Whole grain rice: Updated understanding of starch digestibility and the regulation of glucose and lipid metabolism.

Nowadays, resulting from disordered glucose and lipid metabolism, metabolic diseases (e.g., hyperglycemia, type 2 diabetes, and obesity) are among the most serious health issues facing humans worldwide. Increasing evidence has confirmed that dietary intervention (with healthy foods) is effective at regulating the metabolic syndrome. Whole grain rice (WGR) rich in dietary fiber and many bioactive compounds (e.g., γ-amino butyric acid, γ-oryzanol, and polyphenols) can not only inhibit starch digestion and prevent rapid increase in the blood glucose level, but also reduce oxidative stress and damage to the liver, thereby regulating glucose and lipid metabolism. The rate of starch digestion is directly related to the blood glucose level in the organism after WGR intake. Therefore, the effects of different factors (e.g., additives, cooking, germination, and physical treatments) on WGR starch digestibility are examined in this review. In addition, the mechanisms from human and animal experiments regarding the correlation between the intake of WGR or its products and the lowered blood glucose and lipid levels and the reduced incidence of diabetes and obesity are discussed. Moreover, information on developing WGR products with the health benefits is provided.

Cellulose-starch Hybrid Films Plasticized by Aqueous ZnCl2 Solution.

Starch and cellulose are two typical natural polymers from plants that have similar chemical structures. The blending of these two biopolymers for materials development is an interesting topic, although how their molecular interactions could influence the conformation and properties of the resultant materials has not been studied extensively. Herein, the rheological properties of cellulose/starch/ZnCl2 solutions were studied, and the structures and properties of cellulose-starch hybrid films were characterized. The rheological study shows that compared with starch (containing mostly amylose), cellulose contributed more to the solution's viscosity and has a stronger shear-thinning behavior. A comparison between the experimental and calculated zero-shear-rate viscosities indicates that compact complexes (interfacial interactions) formed between cellulose and starch with ≤50 wt % cellulose content, whereas a loose structure (phase separation) existed with ≥70 wt % cellulose content. For starch-rich hybrid films prepared by compression molding, less than 7 wt % of cellulose was found to improve the mechanical properties despite the reduced crystallinity of the starch; for cellulose-rich hybrid films, a higher content of starch reduced the material properties, although the chemical interactions were not apparently influenced. It is concluded that the mechanical properties of biopolymer films were mainly affected by the structural conformation, as indicated by the rheological results.

Purification, Characterization and Degradation Performance of a Novel Dextranase from Penicillium cyclopium CICC-4022.

A novel dextranase was purified from Penicillium cyclopium CICC-4022 by ammonium sulfate fractional precipitation and gel filtration chromatography. The effects of temperature, pH and some metal ions and chemicals on dextranase activity were investigated. Subsequently, the dextranase was used to produce dextran with specific molecular mass. Weight-average molecular mass (Mw) and the ratio of weight-average molecular mass/number-average molecular mass, or polydispersity index (Mw/Mn), of dextran were measured by multiple-angle laser light scattering (MALS) combined with gel permeation chromatography (GPC). The dextranase was purified to 16.09-fold concentration; the recovery rate was 29.17%; and the specific activity reached 350.29 U/mg. Mw of the dextranase was 66 kDa, which is similar to dextranase obtained from other Penicillium species reported previously. The highest activity was observed at 55 °C and a pH of 5.0. This dextranase was identified as an endodextranase, which specifically degraded the α-1,6 glucosidic bonds of dextran. According to metal ion dependency tests, Li⁺, Na⁺ and Fe2+ were observed to effectively improve the enzymatic activity. In particular, Li⁺ could improve the activity to 116.28%. Furthermore, the dextranase was efficient at degrading dextran and the degradation rate can be well controlled by the dextranase activity, substrate concentration and reaction time. Thus, our results demonstrate the high potential of this dextranase from Penicillium cyclopium CICC-4022 as an efficient enzyme to produce specific clinical dextrans.

Solubility of starch and microcrystalline cellulose in 1-ethyl-3-methylimidazolium acetate ionic liquid and solution rheological properties.

This study compared the solubility of starch (G50) and microcrystalline cellulose (MCC) in an ionic liquid (IL), 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), at different temperatures. From SAXS and WAXS analysis, polysaccharides could be totally dissolved in [Emim][OAc]. Fourier-transform infrared (FTIR) spectra showed a similar dissolution mechanism for starch and MCC, which was related to the formation of hydrogen bonds between polysaccharide hydroxyls and acetic anions, causing the breakage of the hydrogen bonding network of the polysaccharide. The polysaccharide-[Emim][OAc] solutions displayed viscosity in the order of G50-[Emim][OAc] < G50/MCC-[Emim][OAc] < MCC-[Emim][OAc], which led to speculation that the molecular chain of G50 and MCC existed concordantly in [Emim][OAc]. The intrinsic viscosity study showed that G50 was much less temperature-sensitive than MCC, and G50/MCC solutions showed intermediate and tuned behaviors. Steady-shear measurements indicated that for dilute solutions, there was a slightly shear-thinning behavior at low shear rates, and high concentration solutions presented an apparent shear-thinning behavior at high shear rates. These characteristics also reflect the different conformation of polysaccharide chains in the solution, which guides the processing of polysaccharide materials and composites for the desired structure and properties.

Adsorption of azo dyes from aqueous solution by the hybrid MOFs/GO.

In this work, a hybrid of chromium(III) terephthalate metal organic framework (MIL-101) and graphene oxide (GO) was synthesized and its performance in the removal of azo dyes (Amaranth, Sunset Yellow, and Carmine) from water was evaluated. The adsorption for azo dyes on MIL-101/GO was compared with that of MIL-101, and it was found that the addition of GO enhanced the stability of MIL-101 in water and increased the adsorption capacity. The maximum adsorption capacities of MIL-101/GO were 111.01 mg g(-1) for Amaranth, 81.28 mg g(-1) for Sunset Yellow, and 77.61 mg g(-1) for Carmine. The adsorption isotherms and kinetics were investigated, showing that the adsorption fits the Freundlich isotherm and the pseudo-second-order kinetic model. The recyclability of MIL-101/GO was shown by the regeneration by acetone. The high adsorption capability and excellent reusability make MIL-101/GO a competent adsorbent for the removal dyes from aqueous solution.

Understanding the structural disorganization of starch in water-ionic liquid solutions.

Using synchrotron X-ray scattering analyses and Fourier transform infrared spectroscopy, this work provides insights into the solvent effects of water : [C2mim][OAc] solutions on the disorganization of a starch semi-crystalline structure. When a certain ratio (10.2 : 1 mol/mol) of water : [C2mim][OAc] solution is used, the preferential hydrogen bonding between starch hydroxyls and [OAc](-) anions results in the breakage of the hydrogen bonding network of starch and thus the disruption of starch lamellae. This greatly facilitates the disorganization of starch, which occurs much easier than in pure water. In contrast, when 90.8 : 1 (mol/mol) water : [C2mim][OAc] solution is used, the interactions between [OAc](-) anions and water suppress the solvent effects on starch, thereby making the disorganization of starch less easy than in pure water. All these differences can be shown by changes in the lamellar and fractal structures: firstly, a preferable increase in the thickness of the crystalline lamellae rather than that of the amorphous lamellae causes an overall increase in the thickness of the semi-crystalline lamellae; then, the amorphous lamellae start to decrease probably due to the out-phasing of starch molecules from them; this forms a fractal gel on a larger scale (than the lamellae) which gradually decreases to a stable value as the temperature increases further. It is noteworthy that these changes occur at temperatures far below the transition temperature that is thermally detectable as is normally described. This hints to our future work that using certain aqueous ionic liquids for destructuration of the starch semi-crystalline structure is the key to realize green processes to obtain homogeneous amorphous materials.

Natural polymer starch-based materials for flexible electronic sensor development: A review of recent progress.

In response to the burgeoning interest in the development of highly conformable and resilient flexible electronic sensors capable of transducing diverse physical stimuli, this review investigates the pivotal role of natural polymers, specifically those derived from starch, in crafting sustainable and biocompatible sensing materials. Expounding on cutting-edge research, the exploration delves into innovative strategies employed to leverage the distinctive attributes of starch in conjunction with other polymers for the fabrication of advanced sensors. The comprehensive discussion encompasses a spectrum of starch-based materials, spanning all-starch-based gels to starch-based soft composites, meticulously scrutinizing their applications in constructing resistive, capacitive, piezoelectric, and triboelectric sensors. These intricately designed sensors exhibit proficiency in detecting an array of stimuli, including strain, temperature, humidity, liquids, and enzymes, thereby playing a pivotal role in the continuous and non-invasive monitoring of human body motions, physiological signals, and environmental conditions. The review highlights the intricate interplay between material properties, sensor design, and sensing performance, emphasizing the unique advantages conferred by starch-based materials, such as self-adhesiveness, self-healability, and re-processibility facilitated by dynamic bonding. In conclusion, the paper outlines current challenges and future research opportunities in this evolving field, offering valuable insights for prospective investigations.

Pre-gelatinized high-amylose starch enables easy preparation of flexible and antimicrobial composite films for fresh fruit preservation.

While high-amylose starch (HAS) possesses advantageous properties such as high resistant starch content and favorable mechanical attributes, its gelatinization constraints have limited its applicability. This study enhances its versatility by focusing on pre-gelatinized (PG) HAS with exceptional rehydratability, achieved by disorganizing native HAS granules (with amylose contents of 55 % and 68 %, respectively) using a 33 % CaCl2 solution, followed by water-ethanol precipitation and freeze-drying. The resulting PG-HAS exhibited elevated amylose content (61 % and 75 %) with minimal changes in amylose molecular weight. PG-HAS displayed superior water-absorption index (WAI) and water-soluble index (WSI) compared to native HAS, further improved by 2 % CaCl2 solution incorporation. Furthermore, composite films were prepared by mixing PG-HAS with PVA at a 6:4 (w/w) ratio. The PG-G50 (61 % amylose content)/PVA composite film exhibited remarkable elongation (131.1 ± 5.4 %), nearly three times that of a normal corn starch (NCS, with 27 % amylose)/PVA film, attributed to improved starch dispersity and higher amylose content. Nonetheless, the PG-G70 (75 % amylose content)/PVA film at the same ratio showed lower elongation (54.7 ± 8.0 %), potentially due to strong cohesive forces between amylose chains that impede starch-PVA interactions. Moreover, the PG-HAS/PVA composite films, enriched with antibacterial agents, demonstrated effective antibacterial properties with a gradual and sustained release of active compounds. Notably, the PG-G50/PVA/tannic acid (TA) film effectively preserved fresh apple slices by inhibiting bacteria growth and preventing browning. These findings underscore the excellent rehydration of PG-HAS and its potential as an inner packaging material for irregularly shaped foods, such as sliced fruits or meats, due to its nontoxic nature, softness and flexibility, which allows the film to maintain close contact with food surfaces.

Mastering textural control in multi-polysaccharide gels: Effect of κ-carrageenan, konjac glucomannan, locust bean gum, low-acyl gellan gum, and sodium alginate.

To comprehend the intricate interplay of five common food polysaccharides, κ-Carrageenan (KC), konjac glucomannan (KGM), locust bean gum (LBG), low-acyl gellan gum (LAG), and sodium alginate (SA), within composite polysaccharide gels, widely employed for textural modulation and flavor enhancement. This study systematically modulates the quantities of these five polysaccharides to yield six distinct multi-polysaccharide gels. The unique impact of each polysaccharide on the overall quality of composite gels were studied by thermostability, microstructure, water-holding capacity (WHC), texture, and sensory attributes. The findings unequivocally manifest the phenomenon of thermoreversible gelation in all composite gels, except for the KC-devoid sample, which displayed an inability to solidify. Notably, KGM, LBG, and LAG emerged as pivotal enhancers of the network structure in these composite gels, while SA was identified as a promotor of layered structure, resulting in a reduction of surface hardness. Leveraging principal component analysis (PCA) to analyzed 14 critical evaluation parameters of the five multi-polysaccharide gels, revealing the order as follows: KC > KGM > SA > LAG > LBG. These findings would imparts valuable insights into the pragmatic utilization of multi-polysaccharide gels for the development of food products (e.g. Bobo balls in milk tea) with tailored textural and sensory attributes.

A short linear glucan nanocomposite hydrogel formed by in situ self-assembly with highly elastic, fatigue-resistant and self-recovery.

Polyacrylamide (PAM) hydrogels are widely used in wide-ranging applications in biology, medicine, pharmaceuticals and environmental sectors. However, achieving the requisite mechanical properties, fatigue resistance, self-recovery, biocompatibility, and biodegradability remains a challenge. Herein, we present a facile method to construct a nanocomposite hydrogel by integrating short linear glucan (SLG), obtained by debranching waxy corn starch, into a PAM network through self-assembly. The resulting composite hydrogel with 10 % SLG content exhibited satisfactory stretchability (withstanding over 1200 % strain), along with maximum compressive and shear strengths of about 490 kPa and 39 kPa at 90 % deformation, respectively. The hydrogel demonstrated remarkable resilience and could endure repeated compression and stretching. Notably, the nanocomposite hydrogel with 10 % SLG content exhibited full stress recovery at 90 % compression deformation after 20 s, without requiring specific environmental conditions, achieving an energy dissipation recovery rate of 98 %. Meanwhile, these hydrogels exhibited strong adhesion to various soft and hard substrates, including skin, glasses and metals. Furthermore, they maintain solid integrity at both 37 °C and 50 °C after swelling equilibrium, unlike traditional PAM hydrogels, which exhibited softening under similar conditions. We hope that this PAM-SLG hydrogel will open up new avenues for the development of multifunctional electronic devices, offering enhanced performance and versatility.

Effect of curdlan addition and thermal sterilization on the structural and properties of rice starch gel.

This study delves into the effects of curdlan integration and thermal sterilization on the rheological properties, structure, and quality attributes of concentrated rice starch gel. Acting as a heat-set polysaccharide, curdlan established a dual-network gel structure with rice starch gel, displaying strong interactions with rice starch, as confirmed by confocal laser scanning microscopy and Fourier-transform infrared spectroscopy. The addition of curdlan expedited the gel formation of rice starch, yielding a denser gel structure. Consequently, this enhanced G', solid-like behavior, textural properties, and cooking quality while reducing frequency-dependence. Given the cooling-induced gelation behavior of pure rice starch, thermal treatment disrupted inter-chain hydrogen bonding, compromising the structural integrity of the gel. This disruption manifested in a softer texture and diminished mechanical properties and cooking quality. Notably, this decline in mechanical properties and cooking quality of rice starch gel was markedly ameliorated with the incorporation of curdlan, particularly at a content of ≥1.0 %. Compared with pure RS, 1.0 % CD inclusion showed a reduction in cooking breakage rate by 30.69 % and an increase in hardness by 38.04 %. This work provides valuable insights for the advancement of fresh starch gel-based foods that exhibit exceptional quality and an extended shelf life.

Revisiting various mechanistic approaches for cellulose dissolution in different solvent systems: A comprehensive review.

The process of dissolving cellulose is a pivotal step in transforming it into functional, value-added materials, necessitating a thorough comprehension of the underlying mechanisms to refine its advanced processing. This article reviews cellulose dissolution using various solvent systems, along with an in-depth exploration of the associated dissolution mechanisms. The efficacy of different solvents, including aqueous solvents, organic solvents, ionic liquids, hybrid ionic liquid/cosolvent systems, and deep eutectic solvents, in dissolving cellulose is scrutinized, and their limitations and advantages are highlighted. In addition, this review methodically outlines the mechanisms at play within these various solvent systems and the factors influencing cellulose solubility. Conclusions drawn highlight the integral roles of the degree of polymerization, crystallinity, particle size, the type and sizes of cations and anions, alkyl chain length, ionic liquid/cosolvent ratio, viscosity, solvent acidity, basicity, and hydrophobic interactions in the dissolution process. This comprehensive review aims to provide valuable insights for researchers investigating biopolymer dissolution in a broader context, thereby paving the way for broader applications and innovations of these solvent systems.

Effect of soybean polysaccharide and soybean oil on gelatinization and retrogradation properties of corn starch.

This investigation stems from the wide interest in mitigating starch retrogradation, which profoundly impacts the quality of starch-based food, garnering significant attention in the contemporary food industry. Our study delves into the intricate dynamics of soluble soybean polysaccharide (SSPS) and soybean oil (SO) when added individually or in combination to native corn starch (NCS), offering insights into the gelatinization and retrogradation phenomena. We observed that SSPS (0.5 %, w/w) hindered starch swelling, leading to an elevated gelatinization enthalpy change (∆H) value, while SO (0.5 %, w/w) increased ∆H due to its hydrophobicity. Adding SSPS and/or SO concurrently reduced the viscosity and storage modulus (G') of starch matrix. For the starch gel (8 %, w/v) after refrigeration, SSPS magnified water-holding capacity (WHC) and decreased hardness through hydrogen bonding with starch, while SO increased hardness with limited water retention. Crucially, the combination of SSPS and SO maximized WHC, minimized hardness, and significantly inhibited starch retrogradation. The specific ratio of SSPS to SO was found to significantly influence the starch properties, with a 1:1 ratio resulting in the most desirable quality for application in starch-based foods. This study offers insights for utilizing polysaccharides and lipids in starch-based food products to extend shelf life.

Towards superior biopolymer gels by enabling interpenetrating network structures: A review on types, applications, and gelation strategies.

Gels derived from single networks of natural polymers (biopolymers) typically exhibit limited physical properties and thus have seen constrained applications in areas like food and medicine. In contrast, gels founded on a synergy of multiple biopolymers, specifically polysaccharides and proteins, with intricate interpenetrating polymer network (IPN) structures, represent a promising avenue for the creation of novel gel materials with significantly enhanced properties and combined advantages. This review begins with the scrutiny of newly devised IPN gels formed through a medley of polysaccharides and/or proteins, alongside an introduction of their practical applications in the realm of food, medicine, and environmentally friendly solutions. Finally, based on the fact that the IPN gelation process and mechanism are driven by different inducing factors entwined with a diverse amalgamation of polysaccharides and proteins, our survey underscores the potency of physical, chemical, and enzymatic triggers in orchestrating the construction of crosslinked networks within these biomacromolecules. In these mixed systems, each specific inducer aligns with distinct polysaccharides and proteins, culminating in the generation of semi-IPN or fully-IPN gels through the intricate interpenetration between single networks and polymer chains or between two networks, respectively. The resultant IPN gels stand as paragons of excellence, characterized by their homogeneity, dense network structures, superior textural properties (e.g., hardness, elasticity, adhesion, cohesion, and chewability), outstanding water-holding capacity, and heightened thermal stability, along with guaranteed biosafety (e.g., nontoxicity and biocompatibility) and biodegradability. Therefore, a judicious selection of polymer combinations allows for the development of IPN gels with customized functional properties, adept at meeting precise application requirements.

Chitosan-based electroconductive inks without chemical reaction for cost-effective and versatile 3D printing for electromagnetic interference (EMI) shielding and strain-sensing applications.

The burgeoning interest in biopolymer 3D printing arises from its capacity to meticulously engineer tailored, intricate structures, driven by the intrinsic benefits of biopolymers-renewability, chemical functionality, and biosafety. Nevertheless, the accessibility of economical and versatile 3D-printable biopolymer-based inks remains highly constrained. This study introduces an electroconductive ink for direct-ink-writing (DIW) 3D printing, distinguished by its straightforward preparation and commendable printability and material properties. The ink relies on chitosan as a binder, carbon fibers (CF) a low-cost electroactive filler, and silk fibroin (SF) a structural stabilizer. Freeform 3D printing manifests designated patterns of electroconductive strips embedded in an elastomer, actualizing effective strain sensors. The ink's high printability is demonstrated by printing complex geometries with porous, hollow, and overhanging structures without chemical or photoinitiated reactions or support baths. The composite is lightweight (density 0.29 ± 0.01 g/cm3), electroconductive (2.64 ± 0.06 S/cm), and inexpensive (20 USD/kg), with tensile strength of 20.77 ± 0.60 MPa and Young's modulus of 3.92 ± 0.06 GPa. 3D-printed structures exhibited outstanding electromagnetic interference (EMI) shielding effectiveness of 30-31 dB, with shielding of >99.9 % incident electromagnetic waves, showcasing significant electronic application potential. Thus, this study presents a novel, easily prepared, and highly effective biopolymer-based ink poised to advance the landscape of 3D printing technologies.