Direct Determination of the Structure of Single Biopolymer Molecules Using Nanopore Sequencing.

This review highlights operational principles, features, and modern aspects of the development of third-generation sequencing technology of biopolymers focusing on the nucleic acids analysis, namely the nanopore sequencing system. Basics of the method and technical solutions used for its realization are considered, from the first works showing the possibility of creation of these systems to the easy-to-handle procedure developed by Oxford Nanopore Technologies company. Moreover, this review focuses on applications, which were developed and realized using equipment developed by the Oxford Nanopore Technologies, including assembly of whole genomes, methagenomics, direct analysis of the presence of modified bases.

Application of bacteriophages in biopolymer-based functional food packaging films.

Recently, food spoilage caused by pathogens has been increasing. Therefore, applying control strategies is essential. Bacteriophages can potentially reduce this problem due to their host specificity, ability to inhibit bacterial growth, and extend the shelf life of food. When bacteriophages are applied directly to food, their antibacterial activity is lost. In this regard, bacteriophage-loaded biopolymers offer an excellent option to improve food safety by extending their shelf life. Applying bacteriophages in food preservation requires comprehensive and structured information on their isolation, culturing, storage, and encapsulation in biopolymers for active food packaging applications. This review focuses on using bacteriophages in food packaging and preservation. It discusses the methods for phage application on food, their use for polymer formulation and functionalization, and their effect in enhancing food matrix properties to obtain maximum antibacterial activity in food model systems.

Can bioplastics always offer a truly sustainable alternative to fossil-based plastics?

Bioplastics, comprised of bio-based and/or biodegradable polymers, have the potential to play a crucial role in the transition towards a sustainable circular economy. The use of biodegradable polymers not only leads to reduced greenhouse gas emissions but also might address the problem of plastic waste persisting in the environment, especially when removal is challenging. Nevertheless, biodegradable plastics should not be considered as substitutes for proper waste management practices, given that their biodegradability strongly depends on environmental conditions. Among the challenges hindering the sustainable implementation of bioplastics in the market, the development of effective downstream recycling routes is imperative, given the increasing production volumes of these materials. Here, we discuss about the most advisable end-of-life scenarios for bioplastics. Various recycling strategies, including mechanical, chemical or biological (both enzymatic and microbial) approaches, should be considered. Employing enzymes as biocatalysts emerges as a more selective and environmentally friendly alternative to chemical recycling, allowing the production of new bioplastics and added value and high-quality products. Other pending concerns for industrial implementation of bioplastics include misinformation among end users, the lack of a standardised bioplastic labelling, unclear life cycle assessment guidelines and the need for higher financial investments. Although further research and development efforts are essential to foster the sustainable and widespread application of bioplastics, significant strides have already been made in this direction.

Heat flows enrich prebiotic building blocks and enhance their reactivity.

The emergence of biopolymer building blocks is a crucial step during the origins of life1-6. However, all known formation pathways rely on rare pure feedstocks and demand successive purification and mixing steps to suppress unwanted side reactions and enable high product yields. Here we show that heat flows through thin, crack-like geo-compartments could have provided a widely available yet selective mechanism that separates more than 50 prebiotically relevant building blocks from complex mixtures of amino acids, nucleobases, nucleotides, polyphosphates and 2-aminoazoles. Using measured thermophoretic properties7,8, we numerically model and experimentally prove the advantageous effect of geological networks of interconnected cracks9,10 that purify the previously mixed compounds, boosting their concentration ratios by up to three orders of magnitude. The importance for prebiotic chemistry is shown by the dimerization of glycine11,12, in which the selective purification of trimetaphosphate (TMP)13,14 increased reaction yields by five orders of magnitude. The observed effect is robust under various crack sizes, pH values, solvents and temperatures. Our results demonstrate how geologically driven non-equilibria could have explored highly parallelized reaction conditions to foster prebiotic chemistry.

From Natural Microbe Screening to Sustained Chitinase Activity in Exogenous Hosts.

Genetic parts and hosts can be sourced from nature to realize new functions for synthetic biology or to improve performance in a particular application environment. Here, we proceed from the discovery and characterization of new parts to stable expression in new hosts with a particular focus on achieving sustained chitinase activity. Chitinase is a key enzyme for various industrial applications that require the breakdown of chitin, the second most abundant biopolymer on the earth. Diverse microbes exhibit chitinase activity, but for applications, the environmental conditions for optimal enzyme activity and microbe fitness must align with the application context. Achieving sustained chitinase activity under broad conditions in heterologous hosts has also proven difficult due to toxic side effects. Toward addressing these challenges, we first screen ocean water samples to identify microbes with chitinase activity. Next, we perform whole genome sequencing and analysis and select a chitinase gene for heterologous expression. Then, we optimize transformation methods for target hosts and introduce chitinase. Finally, to achieve robust function, we optimize ribosome binding sites and discover a beneficial promoter that upregulates chitinase expression in the presence of colloidal chitin in a sense-and-respond fashion. We demonstrate chitinase activity for >21 days in standard (Escherichia coli) and nonstandard (Roseobacter denitrificans) hosts. Besides enhancing chitinase applications, our pipeline is extendable to other functions, identifies natural microbes that can be used directly in non-GMO contexts, generates new parts for synthetic biology, and achieves weeks of stable activity in heterologous hosts.

Comparative proteomic analysis of papaya bud flowers reveals metabolic signatures and pathways driving hermaphrodite development.

Papaya (Carica papaya) is a trioecious species with female, male, and hermaphrodite plants. Given the sex segregation, selecting hermaphroditic plants is vital for orchard establishment due to their greater commercial value. However, selecting hermaphrodite plants through sexing is laborious and costly. Moreover, environmental stressors can exacerbate the issue by potentially inducing abnormal flower development, thus affecting fruit quality. Despite these challenges, the molecular mechanisms governing sex development in papaya remain poorly understood. Thus, this study aimed to identify proteins associated with sex development in female and hermaphrodite flowers of papaya through comparative proteomic analysis. Proteins from flower buds at the early and late developmental stages of three papaya genotypes (UENF-CALIMAN 01, JS12, and Sunrise Solo 72/12) were studied via proteomic analysis via the combination of the shotgun method and nanoESI-HDMSE technology. In buds at an early stage of development, 496 (35.9%) proteins exhibited significantly different abundances between sexes for the SS72/12 genotype, 139 (10%) for the JS12 genotype, and 165 (11.9%) for the UC-01 genotype. At the final stage of development, there were 181 (13.5%) for SS72/12, 113 (8.4%) for JS12, and 125 (9.1%) for UC-01. The large group of differentially accumulated proteins (DAPs) between the sexes was related to metabolism, as shown by the observation of only the proteins that exhibited the same pattern of accumulation in the three genotypes. Specifically, carbohydrate metabolism proteins were up-regulated in hermaphrodite flower buds early in development, while those linked to monosaccharide and amino acid metabolism increased during late development. Enrichment of sporopollenin and phenylpropanoid biosynthesis pathways characterizes hermaphrodite samples across developmental stages, with predicted protein interactions highlighting the crucial role of phenylpropanoids in sporopollenin biosynthesis for pollen wall formation. Most of the DAPs played key roles in pectin, cellulose, and lignin synthesis and were essential for cell wall formation and male flower structure development, notably in the pollen coat. These findings suggest that hermaphrodite flowers require more energy for development, likely due to complex pollen wall formation. Overall, these insights illuminate the molecular mechanisms of papaya floral development, revealing complex regulatory networks and energetic demands in the formation of male reproductive structures.

Biodegradability of bioplastics in different aquatic environments: A systematic review.

Bioplastics were first introduced as environmentally friendly materials, with properties similar to those of conventional plastics. A bioplastic is defined as biodegradable if it can be decomposed into carbon dioxide under aerobic degradation, or methane and CO2 under anaerobic conditions, inorganic compounds, and new cellular biomass, by the action of naturally occurring microorganisms. This definition however does not provide any information on the environmental conditions, timescale and extent at which decomposition processes should occur. With regard to the aquatic environment, recognized standards have been established to assess the ability of plastics to undergo biodegradation; however, these standards fail to provide clear targets to be met to allow labelling of a bioplastic as biodegradable. Moreover, these standards grant the user an extensive leeway in the choice of process parameters. For these reasons, the comparison of results deriving from different studies is challenging. The authors analysed and discussed the degree of biodegradability of a series of biodegradable bioplastics in aquatic environments (both fresh and salt water) using the results obtained in the laboratory and from on-site testing in the context of different research studies. Biochemical Oxygen Demand (BOD), CO2 evolution, surface erosion and weight loss were the main parameters used by researchers to describe the percentage of biodegradation. The results showed a large variability both in weight loss and BOD, even when evaluating the same type of bioplastics. This confirms the need for a reference range of values to be established with regard to parameters applied in defining the biodegradability of bioplastics.

Magnetic tweezers characterization of the entropic elasticity of intrinsically disordered proteins and peptoids.

Understanding the conformational behavior of biopolymers is essential to unlocking knowledge of their biophysical mechanisms and functional roles. Single-molecule force spectroscopy can provide a unique perspective on this by exploiting entropic elasticity to uncover key biopolymer structural parameters. A particularly powerful approach involves the use of magnetic tweezers, which can easily generate lower stretching forces (0.1-20 pN). For forces at the low end of this range, the elastic response of biopolymers is sensitive to excluded volume effects, and they can be described by Pincus blob elasticity model that allow robust extraction of the Flory polymer scaling exponent. Here, we detail protocols for the use of magnetic tweezers for force-extension measurements of intrinsically disordered proteins and peptoids. We also discuss procedures for fitting low-force elastic curves to the predictions of polymer physics models to extract key conformational parameters.

Liquid-liquid biopolymers aqueous solution segregative phase separation in food: From fundamentals to applications-A review.

As a result of the spontaneous movement of molecules, liquid-liquid biopolymer segregative phase separation takes place in an aqueous solution. The efficacy of this type of separation can be optimized under conditions where variables such as pH, temperature, and molecular concentrations have minimal impact on its dynamics. Recently, interest in the applications of biopolymers and their segregative phase separation-associated molecular stratification has increased, particularly in the food industry, where these methods permit the purification of specific particles and the embedding of microcapsules. The present review offers a comprehensive examination of the theoretical mechanisms that regulate the liquid-liquid biopolymers aqueous solution segregative phase separation, the factors that may exert an impact on this procedure, and the importance of this particular separation method in the context of food science. These discussion points also address existing difficulties and future possibilities related to the use of segregative phase separation in food applications. This highlights the potential for the design of novel functional foods and the enhancement of food properties.

Advances in microbial exoenzymes bioengineering for improvement of bioplastics degradation.

Plastic pollution has become a major global concern, posing numerous challenges for the environment and wildlife. Most conventional ways of plastics degradation are inefficient and cause great damage to ecosystems. The development of biodegradable plastics offers a promising solution for waste management. These plastics are designed to break down under various conditions, opening up new possibilities to mitigate the negative impact of traditional plastics. Microbes, including bacteria and fungi, play a crucial role in the degradation of bioplastics by producing and secreting extracellular enzymes, such as cutinase, lipases, and proteases. However, these microbial enzymes are sensitive to extreme environmental conditions, such as temperature and acidity, affecting their functions and stability. To address these challenges, scientists have employed protein engineering and immobilization techniques to enhance enzyme stability and predict protein structures. Strategies such as improving enzyme and substrate interaction, increasing enzyme thermostability, reinforcing the bonding between the active site of the enzyme and substrate, and refining enzyme activity are being utilized to boost enzyme immobilization and functionality. Recently, bioengineering through gene cloning and expression in potential microorganisms, has revolutionized the biodegradation of bioplastics. This review aimed to discuss the most recent protein engineering strategies for modifying bioplastic-degrading enzymes in terms of stability and functionality, including enzyme thermostability enhancement, reinforcing the substrate binding to the enzyme active site, refining with other enzymes, and improvement of enzyme surface and substrate action. Additionally, discovered bioplastic-degrading exoenzymes by metagenomics techniques were emphasized.

Essential oil-loaded biopolymeric particles on food industry and packaging: A review.

Essential oils (EOs) are liquid extracts derived from various parts of herbal or medicinal plants. They are widely accepted in food packaging due to their bioactive components, which exhibit remarkable antioxidant and antimicrobial properties against various pathogenic and food spoilage microorganisms. However, the functional efficacy of EOs is hindered by the high volatility of their bioactive compounds, leading to rapid release. Combining biopolymers with EOs forms a complex network within the polymeric matrix, reducing the volatility of EOs, controlling their release, and enhancing thermal and mechanical stability, favoring their application in food packaging or processing industries. This study presents a comprehensive overview of techniques used to encapsulate EOs, the natural polymers employed to load EOs, and the functional properties of EOs-loaded biopolymeric particles, along with their potential antioxidant and antimicrobial benefits. Additionally, a thorough discussion is provided on the widespread application of EOs-loaded biopolymers in the food industries. However, research on their utilization in confectionery processing, such as biscuits, chocolates, and others, remains limited. Further studies can be conducted to explore and expand the applications of EOs-loaded biopolymeric particles in food processing industries.

A generalizable reactive blending strategy to construct flame-retardant, mechanically-strong and toughened poly(L-lactic acid) bioplastics.

Poly(L-lactic acid) (PLA) is an environmentally-friendly bioplastic with high mechanical strength, but suffers from inherent flammability and poor toughness. Many tougheners have been reported for PLA, but their synthesis usually involves organic solvents, and they tend to dramatically reduce the mechanical strength and cannot settle the flammability matter. Herein, we develop strong, tough, and flame-retardant PLA composites by reactive blending PLA, 6-((double (2-hydroxyethyl) amino) methyl) dibenzo [c, e] [1,2] oxyphosphate acid 6-oxide (DHDP) and diphenylmethane diisocyanate (MDI) and define it PLA/xGH, where x indicates that the molar ratio of -NCO group in MDI to -OH group in PLA and DHDP is 1.0x: 1. This fabrication requires no solvents. PLA/2GH with a -NCO/-OH molar ratio of 1.02: 1 maintains high tensile strength of 63.0 MPa and achieves a 23.4 % increase in impact strength compared to PLA due to the incorporation of rigid polyurethane chain segment. The vertical combustion (UL-94) classification and limiting oxygen index (LOI) of PLA/2GH reaches V-0 and 29.8 %, respectively, because DHDP and MDI function in gas and condensed phases. This study displays a generalizable strategy to create flame-retardant bioplastics with great mechanical performances by the in-situ formation of P/N-containing polyurethane segment within PLA.

Correlating fluorescence microscopy, optical and magnetic tweezers to study single chiral biopolymers such as DNA.

Biopolymer topology is critical for determining interactions inside cell environments, exemplified by DNA where its response to mechanical perturbation is as important as biochemical properties to its cellular roles. The dynamic structures of chiral biopolymers exhibit complex dependence with extension and torsion, however the physical mechanisms underpinning the emergence of structural motifs upon physiological twisting and stretching are poorly understood due to technological limitations in correlating force, torque and spatial localization information. We present COMBI-Tweez (Combined Optical and Magnetic BIomolecule TWEEZers), a transformative tool that overcomes these challenges by integrating optical trapping, time-resolved electromagnetic tweezers, and fluorescence microscopy, demonstrated on single DNA molecules, that can controllably form and visualise higher order structural motifs including plectonemes. This technology combined with cutting-edge MD simulations provides quantitative insight into complex dynamic structures relevant to DNA cellular processes and can be adapted to study a range of filamentous biopolymers.

Using waste biomass to produce 3D-printed artificial biodegradable structures for coastal ecosystem restoration.

The loss of ecosystem functions and services caused by rapidly declining coastal marine ecosystems, including corals and bivalve reefs and wetlands, around the world has sparked significant interest in interdisciplinary methods to restore these ecologically and socially important ecosystems. In recent years, 3D-printed artificial biodegradable structures that mimic natural life stages or habitat have emerged as a promising method for coastal marine restoration. The effectiveness of this method relies on the availability of low-cost biodegradable printing polymers and the development of 3D-printed biomimetic structures that efficiently support the growth of plant and sessile animal species without harming the surrounding ecosystem. In this context, we present the potential and pathway for utilizing low-cost biodegradable biopolymers from waste biomass as printing materials to fabricate 3D-printed biodegradable artificial structures for restoring coastal marine ecosystems. Various waste biomass sources can be used to produce inexpensive biopolymers, particularly those with the higher mechanical rigidity required for 3D-printed artificial structures intended to restore marine ecosystems. Advancements in 3D printing methods, as well as biopolymer modifications and blending to address challenges like biopolymer solubility, rheology, chemical composition, crystallinity, plasticity, and heat stability, have enabled the fabrication of robust structures. The ability of 3D-printed structures to support species colonization and protection was found to be greatly influenced by their biopolymer type, surface topography, structure design, and complexity. Considering limited studies on biodegradability and the effect of biodegradation products on marine ecosystems, we highlight the need for investigating the biodegradability of biopolymers in marine conditions as well as the ecotoxicity of the degraded products. Finally, we present the challenges, considerations, and future perspectives for designing tunable biomimetic 3D-printed artificial biodegradable structures from waste biomass biopolymers for large-scale coastal marine restoration.

The effect of biopolymer gel derived from sugarcane on healing of traumatic oral ulcers: an experimental study.

PURPOSE: The extracellular polysaccharide (EPS) is produced by the bacterium Zoogloea sp. and plays a positive role in tissue repair. The purpose of this study was to clinically and histologically compare the effects of EPS in the healing of traumatic oral ulcers in rats with the effects of triamcinolone. METHODS: Ulcers were induced in the oral mucous of 45 male Wistar rats, divided into three groups: control group, treated with triamcinolone, and treated with biopolymer gel. In the clinical evaluation, we considered the weight variation of the animals and the size of the lesion area, at baseline and on treatment days 1, 3 and 7. The histological parameters evaluated were the type and intensity of the inflammatory infiltration, the presence of necrosis and foreign body granuloma and the degree of re-epithelialization of the lesion. RESULTS: The reduction of the lesion area was greater in the animals treated with EPS, with no difference in the intensity of the inflammatory infiltration between the groups on days 3 and 7 of treatment. CONCLUSIONS: The results suggest that topical application of EPS in traumatic oral ulcers of rats promotes faster repair than triamcinolone ointment, without increasing the intensity of inflammatory infiltration under the lesion.

Development and techno-economic analysis of Grewia biopolymer-based dual coagulant system for wastewater treatment at pilot scale.

Use of Grewia biopolymer as a natural coagulant aid was explored in a dual-coagulant system (conventional coagulant + biopolymer) for wastewater treatment. Such use not only improved turbidity removal efficiency over a wide pH range (5-9) but also helped reducing the concentration demand of inorganic coagulants by 25-50 %. Response surface methodology was employed for investigating the interaction between factors (initial pH, coagulant, and biopolymer concentration) affecting coagulation/flocculation of aqueous laterite suspension, and process optimization for more than 80 % turbidity removal in the desired final pH range (6-7). Mechanisms potentially involved in coagulation/flocculation using biopolymer was elucidated. Techno-economic assessment indicated the feasibility of pilot-scale production of the biopolymer and its use in wastewater treatment. This study demonstrates that Grewia biopolymer has the potential to be used as a coagulant aid and will help researchers select appropriate markets for further cost reduction and successful implementation of biopolymer-based wastewater treatment.

Cold Alkali-Extractable Antioxidative Polysaccharide from Russula pseudocyanoxantha (Agaricomycetes), a Novel Mushroom, Stimulates Immune Responses in RAW264.7 Cells by Regulating the TLR/NF-κB Pathway.

In our previous study, we have established Russula pseudocyanoxantha as a unique species, playing a crucial role in indigenous diets through ages. The research also brought attention to bioactive potential of polysaccharide fraction extracted from the unexplored food using hot water. However, residue of the conventional process still contains therapeutic biopolymers that could further be utilized for pharmacological purposes instead of being discarded. Therefore, the current study aims to valorize the solid remnants, contributing to a deeper understanding of the novel taxon. Subsequently, the leftover was treated with cold alkali, leading to the preparation of a high-yield fraction (RP-CAP). Chemical characterization through FT-IR, GC-MS, HPTLC, and spectroscopy demonstrated presence of several monomers in the carbohydrate backbone, predominantly composed of ß-glucan. Furthermore, GPC chromatogram indicated presence of a homogeneous polymer with molecular weight of ~ 129.28 kDa. Subsequently, potent antioxidant activity was noted in terms of radical scavenging (O2·-, OH·, DPPH· and ABTS·+), chelating ability, reducing power and total antioxidant activity where EC50 values ranged from 472-3600 µg/mL. Strong immune-boosting effect was also evident, as the biopolymers stimulated murine macrophage cell proliferation, phagocytic activity, pseudopod formation, and NO as well as ROS synthesis particularly at the concentration of 100 µg/mL. In-depth analysis through RT-PCR revealed that the fraction stimulated synthesis of several inflammatory mediators, elucidating the mode of action through TLR/ NF-κB pathway. Therefore, the findings collectively suggest that RP-CAP possesses great potential to serve as a healthimproving component in functional food and pharmaceutical sectors.

Nanoengineered Polymeric RNA Nanoparticles for Controlled Biodistribution and Efficient Targeted Cancer Therapy.

RNA nanotechnology, including rolling circle transcription (RCT), has gained increasing interest as a fascinating siRNA delivery nanoplatform for biostable and tumor-targetable RNA-based therapies. However, due to the lack of fine-tuning technologies for RNA nanostructures, the relationship between physicochemical properties and siRNA efficacy of polymeric siRNA nanoparticles (PRNs) with different sizes has not yet been fully elucidated. Herein, we scrutinized the effects of size/surface chemistry-tuned PRNs on the biological and physiological interactions with tumors. PRNs with adjusted size and surface properties were prepared using sequential engineering processes: RCT, condensation, and nanolayer deposition of functional biopolymers. Through the RCT process, nanoparticles of three sizes with a diameter of 50-200 nm were fabricated and terminated with three types of biopolymers: poly-l-lysine (PLL), poly-l-glutamate (PLG), and hyaluronic acid (HA) for different surface properties. Among the PRNs, HA-layered nanoparticles with a diameter of ∼200 nm exhibited the most effective systemic delivery, resulting in superior anticancer effects in an orthotopic breast tumor model due to the CD44 receptor targeting and optimized nanosized structure. Depending on the type of PRNs, the in vivo siRNA delivery with protein expression inhibition differed by up to approximately 20-fold. These findings indicate that the types of layered biopolymers and the PRNs size mediate efficient polymeric siRNA delivery to the targeted tumors, resulting in high RNAi-induced therapeutic efficacy. This RNA-nanotechnology-based size/surface editing can overcome the limitations of siRNA therapeutics and represents a potent built-in module method to design RNA therapeutics tailored for targeted cancer therapy.

Complicaciones perianales causadas por agentes modeladores inyectados en glúteos / Perianal complications caused by gluteal injection of modeling agents

En este reporte presentamos tres pacientes en quienes ocurrieron condiciones inflamatorias perianales tardías, luego de la administración de sustancias modeladoras no identificadas en los glúteos. El diagnóstico inicial y supuesto no fue correcto, ya que no se investigó durante la evaluación preliminar el antecedente de la administración de elementos modeladores. Recomendamos que los pacientes con patologías inflamatorias del ano, sobre todo aquellos cuyo curso es extraño, se les pregunte acerca de la administración de agentes modeladores en los glúteos. Esta práctica puede contribuir a la eficacia del diagnóstico de manifestaciones perianales caracterizadas por flogosis, que se presentan de forma inusual. (AU)

In this report we present three patients in which late perianal inflammatory conditions occurred after administration of unidentified modeling agents to the buttocks. The initial diagnosis was not correct because of the administration of modeling agents was not investigated during the initial eval-uation. We recommend inquiring patients with inflammatory pathologies of the anus, especially those whose course is unusual, about the adminis-tration of modeling agents to the buttocks. This approach can contribute to the efficiency of the diagnosis of perianal complaints characterized by inflammation, but rare in its appearance. (AU)

Protein-based microneedles for biomedical applications: A systematic review.

Microneedles are minimally-invasive devices with the unique capability of bypassing physiological barriers. Hence, they are widely used for different applications from drug/vaccine delivery to diagnosis and cosmetic fields. Recently, natural biopolymers (particularly carbohydrates and proteins) have garnered attention as safe and biocompatible materials with tailorable features for microneedle construction. Several review articles have dealt with carbohydrate-based microneedles. This review aims to highlight the less-noticed role of proteins through a systematic search strategy based on the PRISMA guideline from international databases of PubMed, Science Direct, Scopus, and Google Scholar. Original English articles with the keyword "microneedle(s)" in their titles along with at least one of the keywords "biopolymers, silk, gelatin, collagen, zein, keratin, fish-scale, mussel, and suckerin" were collected and those in which the proteins undertook a structural role were screened. Then, we focused on the structures and applications of protein-based microneedles. Also, the unique features of some protein biopolymers that make them ideal for microneedle construction (e.g., excellent mechanical strength, self-adhesion, and self-assembly), as well as the challenges associated with them were reviewed. Altogether, the proteins identified so far seem not only promising for the fabrication of "better" microneedles in the future but also inspiring for designing biomimetic structural biopolymers with ideal characteristics.