Colloidal aspects of Janus-like hairy cellulose nanocrystalloids

Biopolymer-Based Nanomedicine for Cancer Therapy: Opportunities and Challenges

Cancer, as the foremost challenge among human diseases, has plagued medical professionals for many years. While there have been numerous treatment approaches in clinical practice, they often cause additional harm to patients. The emergence of nanotechnology has brought new directions for cancer treatment, which can deliver anticancer drugs specifically to tumor areas. This article first introduces the application scenarios of nanotherapies and treatment strategies of nanomedicine. Then, the noteworthy characteristics exhibited by biopolymer materials were described, which make biopolymers stand out in polymeric nanomedicine delivery. Next, we focus on summarizing the state-of-art studies of five categories of proteins (Albumin, Gelatin, Silk fibroin, Zein, Ferritin), nine varieties of polysaccharides (Chitosan, Starch, Hyaluronic acid, Dextran, cellulose, Fucoidan, Carrageenan, Lignin, Pectin) and liposomes in the field of anticancer drug delivery. Finally, we also provide a summary of the advantages and limitations of these biopolymers, discuss the prevailing impediments to their application, and discuss in detail the prospective research directions. This review not only helps readers understand the current development status of nano anticancer drug delivery systems based on biopolymers, but also is helpful for readers to understand the properties of various biopolymers and find suitable solutions in this field through comparative reading.

Multifunctional self-healing hydrogels via nanoengineering of colloidal and polymeric cellulose

The unique features of self-healing hydrogels hold great potential for biomedical applications including injectable hydrogels for cancer treatment, procedures for tumor removal or resection. However, the fabrication of durable and multifunctional self-healing hydrogels composed of biocompatible, green building blocks via versatile synthetic methodology continues to pose a significant challenge. Here, we engineered dialdehyde cellulose (DAC, as a macromolecular bio-crosslinker), and electrosterically stabilized nanocrystalline cellulose (ENCC, as a ligand-targeted drug carrier) to facilitate a strategy for the construction of self-healing hydrogels. Benefiting from its high carboxyl group density, ENCC was functionalized with folic acid (FA) using a non-toxic DMTMM coupling agent and loaded with doxorubicin (DOX, a model drug) through electrostatic interactions. A natural self-healing hydrogel was prepared from carboxymethyl chitosan (CCTS) and DAC mixed with DOX-loaded FA-ENCC using dynamic Schiff-base and hydrogen linkages. A combination of active supramolecular and vital covalent junctions led to a soft (storage modulus ∼500 Pa) and durable material, with rapid (< 5 min) reconstruction of molecular structure from fractured and injected to intact forms. The DAC-CCTS hydrogel showed an appreciable loading capacity of ∼5 mg g-1. Biocompatibility of the hydrogels was evaluated using cell viability and metabolic activity assays, showing lower metabolic activity due to sustained release of its cargo. These materials offer a versatile, sustainable, and green platform for the efficient construction of hydrogels, based on macro- and nano-engineered cellulose, the most abundant and easily accessible biopolymer.

Mussel-Inspired Nanocellulose Coating for Selective Neodymium Recovery

Neodymium (Nd) is one of the most in-demand rare earth elements (REEs) for developing the next generation of magnetic medical devices and clean energy. Eco-friendly and sustainable nanotechnology for REE recovery may be highly suitable to address the limited global supply while minimizing the environmental footprints of current practice, such as solvent extraction. Here, we present a novel one-step mussel-inspired nanocellulose coating (MINC) using bifunctional hairy cellulose nanocrystals (BHCNC), bearing dialdehyde and dicarboxylate groups. The dialdehyde groups enable dopamine-mediated orthogonal conjugation of BHCNC to substrates, such as microparticles, while the high content of dicarboxylate groups yields high-capacity and selective Nd removal against ferric, calcium, and sodium ions. To the best of our knowledge, the MINC-treated substrate provides the most rapid selective removal and recovery of Nd ions even at low Nd concentrations with a capacity that is among the highest reported values. We envision that the MINC will provide new opportunities in developing next-generation bio-based materials and interfaces for the sustainable recovery of REEs and other precious elements.

Target-Specific Delivery and Bioavailability of Pharmaceuticals via Janus and Dendrimer Particles

Nanosized Janus and dendrimer particles have emerged as promising nanocarriers for the target-specific delivery and improved bioavailability of pharmaceuticals. Janus particles, with two distinct regions exhibiting different physical and chemical properties, provide a unique platform for the simultaneous delivery of multiple drugs or tissue-specific targeting. Conversely, dendrimers are branched, nanoscale polymers with well-defined surface functionalities that can be designed for improved drug targeting and release. Both Janus particles and dendrimers have demonstrated their potential to improve the solubility and stability of poorly water-soluble drugs, increase the intracellular uptake of drugs, and reduce their toxicity by controlling the release rate. The surface functionalities of these nanocarriers can be tailored to specific targets, such as overexpressed receptors on cancer cells, leading to enhanced drug efficacy The design of these nanocarriers can be optimized by tuning the size, shape, and surface functionalities, among other parameters. The incorporation of Janus and dendrimer particles into composite materials to create hybrid systems for enhancing drug delivery, leveraging the unique properties and functionalities of both materials, can offer promising outcomes. Nanosized Janus and dendrimer particles hold great promise for the delivery and improved bioavailability of pharmaceuticals. Further research is required to optimize these nanocarriers and bring them to the clinical setting to treat various diseases. This article discusses various nanosized Janus and dendrimer particles for target-specific delivery and bioavailability of pharmaceuticals. In addition, the development of Janus-dendrimer hybrid nanoparticles to address some limitations of standalone nanosized Janus and dendrimer particles is discussed.

Target-Specific Delivery and Bioavailability of Pharmaceuticals via Janus and Dendrimer Particles

Nanosized Janus and dendrimer particles have emerged as promising nanocarriers for the target-specific delivery and improved bioavailability of pharmaceuticals. Janus particles, with two distinct regions exhibiting different physical and chemical properties, provide a unique platform for the simultaneous delivery of multiple drugs or tissue-specific targeting. Conversely, dendrimers are branched, nanoscale polymers with well-defined surface functionalities that can be designed for improved drug targeting and release. Both Janus particles and dendrimers have demonstrated their potential to improve the solubility and stability of poorly water-soluble drugs, increase the intracellular uptake of drugs, and reduce their toxicity by controlling the release rate. The surface functionalities of these nanocarriers can be tailored to specific targets, such as overexpressed receptors on cancer cells, leading to enhanced drug efficacy The design of these nanocarriers can be optimized by tuning the size, shape, and surface functionalities, among other parameters. The incorporation of Janus and dendrimer particles into composite materials to create hybrid systems for enhancing drug delivery, leveraging the unique properties and functionalities of both materials, can offer promising outcomes. Nanosized Janus and dendrimer particles hold great promise for the delivery and improved bioavailability of pharmaceuticals. Further research is required to optimize these nanocarriers and bring them to the clinical setting to treat various diseases. This article discusses various nanosized Janus and dendrimer particles for target-specific delivery and bioavailability of pharmaceuticals. In addition, the development of Janus-dendrimer hybrid nanoparticles to address some limitations of standalone nanosized Janus and dendrimer particles is discussed.

Nanoengineering the Redispersibility of Cellulose Nanocrystals

Enhancing the redispersibility of dried colloidal particles to yield stable dispersions after rehydration is a persistent challenge in the sustainable processing of nanocelluloses due to hydrogen bonding-induced irreversible aggregation. Programming nanocelluloses, such as cellulose nanocrystals (CNC), with moieties that enable colloidal repulsion after rehydration may address this challenge and contribute to the United Nation (UN)'s sustainable development goals (SDGs) of urban development and sustainable living (SDGs 9 and 11) and cradle-to-cradle processing (SDG 12). We hypothesize that imparting electrosteric repulsion to CNC via polyanionic disordered cellulose chains (hairs) protruding from each end may render the dried nanocrystals highly redispersible in aqueous media. Anionic hairy CNC (AHCNC), that is, CNC decorated with dicarboxylated cellulose (DCC) chains, were synthesized by the preferential, successive periodate/chlorite oxidation of the disordered regions of cellulose fibrils, bearing >5 mmol of carboxylate groups per gram. The colloidal properties of AHCNC were compared with those of sulfate half-ester group-functionalized CNC and TEMPO-oxidized CNC (TOCNC) after redispersion in aqueous media, followed by comparing the redispersibility of AHCNC and CNC in aqueous solutions containing monovalent or divalent cations and at varying pH. The AHCNC had remarkable aqueous redispersibility even at high ionic strengths and extreme pH. The unique redispersibility mechanism of dried AHCNC relies on the synergistic steric and electrostatic repulsion forces, recuperated upon the rehydration of DCC. This work may open new opportunities for more sustainable and cost-effective handling and processing of nanocelluloses.

Spatioselective surface chemistry for the production of functional and chemically anisotropic nanocellulose colloids

Maximizing the benefits of nanomaterials from biomass requires unique considerations associated with their native chemical and physical structure. Both cellulose nanofibrils and nanocrystals are extracted from cellulose fibers via a top-down approach and have significantly advanced materials chemistry and set new benchmarks in the last decade. One major challenge has been to prepare defined and selectively modified nanocelluloses, which would, e.g., allow optimal particle interactions and thereby further improve the properties of processed materials. At the molecular and crystallite level, the surface of nanocelluloses offers an alternating chemical structure and functional groups of different reactivity, enabling straightforward avenues towards chemically anisotropic and molecularly patterned nanoparticles via spatioselective chemical modification. In this review, we will explain the influence and role of the multiscale hierarchy of cellulose fibers in chemical modifications, and critically discuss recent advances in selective surface chemistry of nanocelluloses. Finally, we will demonstrate the potential of those chemically anisotropic nanocelluloses in materials science and discuss challenges and opportunities in this field.

Naturally Derived Janus Cellulose Nanomaterials: Anisotropic Cellulose Nanomaterial Building Blocks and Their Assembly into Asymmetric Structures

Naturally derived cellulose nanomaterials (CNMs) with desirable physicochemical properties have drawn tremendous attention for their versatile applications in a broad range of fields. More recently, Janus amphiphilic cellulose nanomaterial particles with asymmetric structures (i.e., reducing and nonreducing ends and crystalline and amorphous domains) have been in the spotlight, offering a rich and sophisticated toolbox for Janus nanomaterials. With careful surface and interfacial engineering, Janus CNM particles have demonstrated great potential as surface modifiers, emulsifiers, stabilizers, compatibilizers, and dispersants in emulsions, nanocomposites, and suspensions. Naturally derived Janus CNM particles offer a fascinating opportunity for scaling up the production of self-standing Janus CNM membranes. Nevertheless, most Janus CNM membranes to date are constructed by asymmetric fabrication or asymmetric modification without considering the Janus traits of CNM particles. More future research should focus on the self-assembly of Janus CNM particles into bulk self-standing Janus CNM membranes to enable more straightforward and sustainable approaches for Janus membranes. This review explores the fabrication, structure-property relationship, and Janus configuration mechanisms of Janus CNM particles and membranes. Janus CNM membranes are highlighted for their versatile applications in liquid, thermal, and light management. This review also highlights the significant advances and future perspectives in the construction and application of sustainable Janus CNM particles and membranes.

Advanced cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) aerogels: Bottom-up assembly perspective for production of adsorbents

The most common and abundant polymer in nature is the linear polysaccharide cellulose, but processing it requires a new approach since cellulose degrades before melting and does not dissolve in ordinary organic solvents. Cellulose aerogels are exceptionally porous (>90 %), have a high specific surface area, and have low bulk density (0.0085 mg/cm³), making them suitable for a variety of sophisticated applications including but not limited to adsorbents. The production of materials with different qualities from the nanocellulose based aerogels is possible thanks to the ease with which other chemicals may be included into the structure of nanocellulose based aerogels; despite processing challenges, cellulose can nevertheless be formed into useful, value-added products using a variety of traditional and cutting-edge techniques. To improve the adsorption of these aerogels, rheology, 3-D printing, surface modification, employment of metal organic frameworks, freezing temperature, and freeze casting techniques were all investigated and included. In addition to exploring venues for creation of aerogels, their integration with CNC liquid crystal formation were also explored and examined to pursue "smart adsorbent aerogels". The objective of this endeavour is to provide a concise and in-depth evaluation of recent findings about the conception and understanding of nanocellulose aerogel employing a variety of technologies and examination of intricacies involved in enhancing adsorption properties of these aerogels.

The Simultaneous Production of Two Distinct Types of Cellulose Nanocrystals

We develop a route to prepare two types of cellulose nanocrystals (CNCs, CNC1 and CNC2) from a unique biomass resource, the fruit shell of Camellia oleifera Abel (SCOA), by integrating sulfuric acid hydrolysis and high-pressure homogenization and examine the effects of hydrolysis time on characteristics of the CNCs during the process. The CNCs exhibit different evolutions in size, morphology, surface charge, and crystallinity with increasing hydrolysis time. While both the CNCs have high crystallinity, CNC1 is of rod-like character with a relatively low aspect ratio, and CNC2 exhibits a hairy appearance with a high aspect ratio. We highlight that controlled acid hydrolysis contributes to the formation of weak spots with an increased susceptibility for homogenizing cellulosic solid residues into hairy CNCs. This is a good step toward tailoring CNC properties in a conventional and scalable approach to maximize their potential applications.

Nanocellulose for Sustainable Water Purification

Nanocelluloses (NC) are nature-based sustainable biomaterials, which not only possess cellulosic properties but also have the important hallmarks of nanomaterials, such as large surface area, versatile reactive sites or functionalities, and scaffolding stability to host inorganic nanoparticles. This class of nanomaterials offers new opportunities for a broad spectrum of applications for clean water production that were once thought impractical. This Review covers substantial discussions based on evaluative judgments of the recent literature and technical advancements in the fields of coagulation/flocculation, adsorption, photocatalysis, and membrane filtration for water decontamination through proper understanding of fundamental knowledge of NC, such as purity, crystallinity, surface chemistry and charge, suspension rheology, morphology, mechanical properties, and film stability. To supplement these, discussions on low-cost and scalable NC extraction, new characterizations including solution small-angle X-ray scattering evaluation, and structure-property relationships of NC are also reviewed. Identifying knowledge gaps and drawing perspectives could generate guidance to overcome uncertainties associated with the adaptation of NC-enabled water purification technologies. Furthermore, the topics of simultaneous removal of multipollutants disposal and proper handling of post/spent NC are discussed. We believe NC-enabled remediation nanomaterials can be integrated into a broad range of water treatments, greatly improving the cost-effectiveness and sustainability of water purification.

Potential use of Janus structures in food applications

Janus surfaces present technological opportunities both for research and industry in which different chemical, physical and/or structural components need to coexist for a single purpose such as chemistry, textile and material science. Varying inorganic and organic (polymer-based) materials are conventionally used however, utilizing nature-derived polymers to fabricate Janus structures is a recent and attractive trend which makes them more applicable for bio-based treatments with environmental concerns. Particularly, promising applications of Janus structures as being surfactants, drug delivery and micro/nano encapsulation vehicles for biomedical purposes successfully forward the interest on Janus concept to the food related practices. Producing Janus structures from nature-derived and food grade polymers such as alginate, cellulose, chitosan, lipid nanocrystals, zein and some plant-proteins and their usage stronger emulsions with higher stabilities, biosensing or antimicrobial practices as well as bioactive delivery and release control might be considered as a new era for food processing industry.

Engineering hairy cellulose nanocrystals for chemotherapy drug capture

Cancer is one of the leading causes of death worldwide, affecting millions of people every year. While chemotherapy remains one of the most common cancer treatments in the world, the severe side effects of chemotherapy drugs impose serious concerns to cancer patients. In many cases, the chemotherapy can be localized to maximize the drug effects; however, the drug systemic circulation induces undesirable side effects. Here, we have developed a highly efficient cellulose-based nanoadsorbent that can capture more than 6000 mg of doxorubicin (DOX), one of the most widely used chemotherapy drugs, per gram of the adsorbent at physiological conditions. Such drug capture capacity is more than 3200% higher than other nanoadsorbents, such as DNA-based platforms. We show how anionic hairy cellulose nanocrystals, also known as electrosterically stabilized nanocrystalline cellulose (ENCC), bind to positively charged drugs in human serum and capture DOX immediately without imposing any cytotoxicity and hemolytic effects. We elucidate how ENCC provides a remarkable platform for biodetoxification at varying pH, ionic strength, ion type, and protein concentration. The outcome of this research may pave the way for developing the next generation in vitro and in vivo drug capture additives and devices.

Deconstruction and Reassembly of Renewable Polymers and Biocolloids into Next Generation Structured Materials

This review considers the most recent developments in supramolecular and supraparticle structures obtained from natural, renewable biopolymers as well as their disassembly and reassembly into engineered materials. We introduce the main interactions that control bottom-up synthesis and top-down design at different length scales, highlighting the promise of natural biopolymers and associated building blocks. The latter have become main actors in the recent surge of the scientific and patent literature related to the subject. Such developments make prominent use of multicomponent and hierarchical polymeric assemblies and structures that contain polysaccharides (cellulose, chitin, and others), polyphenols (lignins, tannins), and proteins (soy, whey, silk, and other proteins). We offer a comprehensive discussion about the interactions that exist in their native architectures (including multicomponent and composite forms), the chemical modification of polysaccharides and their deconstruction into high axial aspect nanofibers and nanorods. We reflect on the availability and suitability of the latter types of building blocks to enable superstructures and colloidal associations. As far as processing, we describe the most relevant transitions, from the solution to the gel state and the routes that can be used to arrive to consolidated materials with prescribed properties. We highlight the implementation of supramolecular and superstructures in different technological fields that exploit the synergies exhibited by renewable polymers and biocolloids integrated in structured materials.

Synthesis and characterization of hairy aminated nanocrystalline cellulose

HYPOTHESIS

The synthesis and characterization of aminated nanocrystalline cellulose (ANCC), a new member of the hairy nanocellulose family, is reported. Hairy nanocelluloses consist of a crystalline rod-like body with amorphous cellulose chains ("hairs") at both ends, on which various functional groups can be accommodated. In ANCC these groups are reactive primary amine groups, which are useful for bioconjugation- and Schiff base-centered modifications. We hypothesize that a two-step oxidation-reductive amination of cellulose fibers followed by hydrothermal treatment will result in the formation of rod-like hairy ANCC.

EXPERIMENTS

ANCC was prepared by converting the aldehyde groups in cellulose, introduced by a periodate oxidation, to primary amines using ammonia and sodium borohydride, followed by a hot water treatment, during which diamine modified cellulose fibers were converted to ANCC. ANCC was characterized by AFM, TEM, DLS, ELS, FTIR, NMR, XPS and conductometric titration. Antibacterial activity of ANCC was assessed by the viable cell counting method.

FINDINGS

ANCC, with an amine content of 5.5 mmol g^-1 is a bare nanocolloid (i.e. non-coated, without adsorbed polyelectrolytes or surfactants) which, as far as we know, has a positive charge density larger than any other bare cationic nanocolloid. It was observed that ANCC particles have a needle-like morphology with a width of ~ 5 nm and a length ~ 120 nm. DLS results proof that ANCC is hairy. Spectroscopic analysis confirmed the introduction of surface primary amine groups. ANCC showed promising bactericidal activities, against Gram-negative species due to their thinner and penetrable cell wall.

Biotemplated Hollow Mesoporous Silica Particles as Efficient Carriers for Drug Delivery

We designed three types of hollow-shaped porous silica materials via a three-step biotemplate-directed method: porous hollow silica nanorods, hollow dendritic fibrous nanostructured silica (DFNS), and ultraporous sponge-like DFNS. The first step was making a biotemplate, for which we used cellulose nanocrystals (CNCs), consisting of rod-shaped nanoparticles synthesized by conventional acid hydrolysis of cellulose fibers. In a second step, core-shell samples were prepared using CNC particles as hard template by two procedures. In the first one, core-shell CNC-silica nanoparticles were synthesized by a polycondensation reaction, which exclusively took place at the surface of the CNCs. In the second procedure, a typical synthesis of DFNS was conducted in a bicontinuous microemulsion with the assistance of additives. DFNS was assembled on the surface of the CNCs, giving rise to core-shell CNC-DFNS structures. Finally, all of the silica-coated CNC composites were calcined, during which the CNC was removed from the core and hollow structures were formed. These materials are very lightweight and highly porous. All three structures were tested as nanocarriers for drug delivery and absorbents for dye removal applications. Dye removal results showed that they can adsorb methylene blue efficiently, with ultraporous sponge-like DFNS showing the highest adsorption capacity, followed by hollow DFNS and hollow silica nanorods. Furthermore, breast cancer cells show a lower cell viability when exposed to doxorubicin-loaded hollow silica nanorods compared with control or doxorubicin cultures, suggesting that the loaded nanorod has a greater anticancer effect than free doxorubicin.

Interaction of hairy carboxyalkyl cellulose nanocrystals with cationic surfactant: Effect of carbon spacer

Tuning the surface chemistry of nanocellulose is essential for developing its end-use applications. Herein, different carboxyalkylated cellulose nanocrystals (CNC) with similar charge densities but with tunable hairy structures were produced. The effect of carbon spacer of the grafted groups on the interaction of the CNC and a cationic surfactant, myristyl trimethyl ammonium bromide (MTAB), at different pH and salinity was explored. The CNC with longer grafted chain length was more hydrophobic, adsorbed more MTAB, and formed a more compact MTAB adlayer than did CNC with the shorter chain length. Also, the adsorption was higher at neutral pH, implying a high electrostatic attraction and hydrophobic interaction between substrates. The hydrophobic interaction of MTAB and hairy CNC in saline systems improved its adsorption. Although MTAB adsorbed more when its concentration was higher than its critical micelle concentration (CMC), the adsorbed adlayer had a less compact structure on the CNC surfaces.

Chemical Modification of Reducing End-Groups in Cellulose Nanocrystals

Native plant cellulose has an intrinsic supramolecular structure. Consequently, it can be isolated as nanocellulose species, which can be utilized as building blocks for renewable nanomaterials. The structure of cellulose also permits its end-wise modification, i.e., chemical reactions exclusively on one end of a cellulose chain or a nanocellulose particle. The premises for end-wise modification have been known for decades. Nevertheless, different approaches for the reactions have emerged only recently, because of formidable synthetic and analytical challenges associated with the issue, including the adverse reactivity of the cellulose reducing end and the low abundance of newly introduced functionalities. This Review gives a full account of the scientific underpinnings and challenges related to end-wise modification of cellulose nanocrystals. Furthermore, we present how the chemical modification of cellulose nanocrystal ends may be applied to directed assembly, resulting in numerous possibilities for the construction of new materials, such as responsive liquid crystal templates and composites with tailored interactions.

Cellulose-based dispersants and flocculants

Natural dispersants and flocculants, often referred to as dispersion stabilizers and liquid-solid separators, respectively, have secured a promising role in the bioprocessing community. They have various applications, including in biomedicine and in environmental remediation. A large fraction of existing dispersants and flocculants are synthesized from non-safe chemical compounds such as polyacrylamide and surfactants. Despite numerous advantages of synthetic dispersants and flocculants, issues such as renewability, sustainability, biocompatibility, and cost efficiency have shifted attention towards natural homologues, in particular, cellulose-based ones. Within the past decade, cellulose derivatives, obtained via chemical and mechanical treatments of cellulose fibrils, have successfully been used for these purposes. In this review article, by dividing the functional cellulosic compounds into "polymeric" and "nanoscale" categories, we provide insight into the engineering pathways, the structural frameworks, and surface chemistry of these "green" types of dispersants and flocculants. A summary of their efficiency and the controlling parameters is also accompanied by recent advances in their applications in each section. We are confident that the emergence of cellulose-based dispersing and flocculating agents will extend the boundaries of sustainable green technology.

Review: Periodate oxidation of wood polysaccharides-Modulation of hierarchies

Periodate oxidation of polysaccharides has transitioned from structural analysis into a modification method for engineered materials. This review summarizes the research on this topic. Fibers, fibrils, crystals, and molecules originating from forests that have been subjected to periodate oxidation can be crosslinked with other entities via the generated aldehyde functionality, that can also be oxidized or reduced to carboxyl or alcohol functionality or used as a starting point for further modification. Periodate-oxidized materials can be subjected to thermal transitions that differ from the native cellulose. Oxidation of polysaccharides originating from forests often features oxidation of structures rather than liberated molecules. This leads to changes in macro, micro, and supramolecular assemblies and consequently to alterations in physical properties. This review focuses on these aspects of the modulation of structural hierarchies due to periodate oxidation.

Janus particles: from concepts to environmentally friendly materials and sustainable applications

Janus particles represent a unique group of patchy particles combining two or more different physical or chemical functionalities at their opposite sides. Especially, individual Janus particles (JPs) with both chemical and geometrical anisotropy as well as their assembled layers provide considerable advantages over the conventional monofunctional particles or surfactant molecules offering (a) a high surface-to-volume ratio; (b) high interfacial activity; (c) target controlling and manipulation of their interfacial activity by external signals such as temperature, light, pH, or ionic strength and achieving switching between stable emulsions and macro-phase separation; (d) recovery and recycling; (e) controlling the mass transport across the interface between the two phases; and finally (f) tunable several functionalities in one particle allowing their use either as carrier materials for immobilized catalytically active substances or, alternatively, their site-selective attachment to substrates keeping another functionality active for further reactions. All these advantages of JPs make them exclusive materials for application in (bio-)catalysis and (bio-)sensing. Considering “green chemistry” aspects covering biogenic materials based on either natural or fully synthetic biocompatible and biodegradable polymers for the design of JPs may solve the problem of toxicity of some existing materials and open new paths for the development of more environmentally friendly and sustainable materials in the very near future. Considering the number of contributions published each year on the topic of Janus particles in general, the number of contributions regarding their environmentally friendly and sustainable applications is by far smaller. This certainly pinpoints an important challenge and is addressed in this review article. The first part of the review focuses on the synthesis of sustainable biogenic or biocompatible Janus particles, as well as strategies for their recovery, recycling, and reusability. The second part addresses recent advances in applications of biogenic/biocompatible and non-biocompatible JPs in environmental and biotechnological fields such as sensing of hazardous pollutants, water decontamination, and hydrogen production. Finally, we provide implications for the rational design of environmentally friendly and sustainable materials based on Janus particles.

Conformational Transformation of pH-Responsive Hairy Cellulose NanoCrystalloids in Salt-Free Dilute Solutions

Among biomaterials, pH-responsive nanoparticles have promising potential for overcoming nonspecific therapeutic delivery by taking advantage of the pH gradient between physiological and pathological states. This article discusses pH-dependent conformations of an organic nanoparticle that has a needle-shaped body from crystalline cellulose, sandwiched between two amorphous regions from chemically nanoengineered dicarboxylated cellulose (DCC). Computational study on a single free DCC chain elucidated that in a salt-free dilute solution, the chain undergoes a major transformation between pH ∼ 3 and ∼6.3. Through this transformation, the DCC chain nature varies from globular neutral polymer to coiled quasi-neutral polymer and finally to rodlike polyelectrolyte. Study on the particle nanostructure indicated that, at pH ∼ 3, the conformation of the amorphous regions is analogous to that of polymer brushes in poor solvents, whereas at pH ∼ 5, the conformation changes to that of quasi-neutral polymer brushes in good solvents. For pH > 6.3, the conformation transforms into that of star-like polyelectrolytes. The height of the amorphous region exhibits a regressive trend up to pH ∼ 6.3, followed by a progressive trend up to pH ∼ 10. Study on the hydrodynamic properties revealed a sharp decline in the diffusion rate as the pH varies from ∼3 to ∼5, followed by a plateau for higher pH. It was demonstrated that, at pH ∼ 3, the nanoparticle may form a coherent nanophase with a rodlike structure. These results may provide insight into designing pH-responsive nanocelluloses with a controlled expansion and diffusion coefficient.

Recent advances in nanoengineering cellulose for cargo delivery

The recent decade has witnessed a growing demand to substitute synthetic materials with naturally-derived platforms for minimizing their undesirable footprints in biomedicine, environment, and ecosystems. Among the natural materials, cellulose, the most abundant biopolymer in the world with key properties, such as biocompatibility, biorenewability, and sustainability has drawn significant attention. The hierarchical structure of cellulose fibers, one of the main constituents of plant cell walls, has been nanoengineered and broken down to nanoscale building blocks, providing an infrastructure for nanomedicine. Microorganisms, such as certain types of bacteria, are another source of nanocelluloses known as bacterial nanocellulose (BNC), which benefit from high purity and crystallinity. Chemical and mechanical treatments of cellulose fibrils made up of alternating crystalline and amorphous regions have yielded cellulose nanocrystals (CNC), hairy CNC (HCNC), and cellulose nanofibrils (CNF) with dimensions spanning from a few nanometers up to several microns. Cellulose nanocrystals and nanofibrils may readily bind drugs, proteins, and nanoparticles through physical interactions or be chemically modified to covalently accommodate cargos. Engineering surface properties, such as chemical functionality, charge, area, crystallinity, and hydrophilicity, plays a pivotal role in controlling the cargo loading/releasing capacity and rate, stability, toxicity, immunogenicity, and biodegradation of nanocellulose-based delivery platforms. This review provides insights into the recent advances in nanoengineering cellulose crystals and fibrils to develop vehicles, encompassing colloidal nanoparticles, hydrogels, aerogels, films, coatings, capsules, and membranes, for the delivery of a broad range of bioactive cargos, such as chemotherapeutic drugs, anti-inflammatory agents, antibacterial compounds, and probiotics. SYNOPSIS: Engineering certain types of microorganisms as well as the hierarchical structure of cellulose fibers, one of the main building blocks of plant cell walls, has yielded unique families of cellulose-based nanomaterials, which have leveraged the effective delivery of bioactive molecules.

Gelatin-polysaccharide composite scaffolds for 3D cell culture and tissue engineering: Towards natural therapeutics

Gelatin is a promising material as scaffold with therapeutic and regenerative characteristics due to its chemical similarities to the extracellular matrix (ECM) in the native tissues, biocompatibility, biodegradability, low antigenicity, cost-effectiveness, abundance, and accessible functional groups that allow facile chemical modifications with other biomaterials or biomolecules. Despite the advantages of gelatin, poor mechanical properties, sensitivity to enzymatic degradation, high viscosity, and reduced solubility in concentrated aqueous media have limited its applications and encouraged the development of gelatin-based composite hydrogels. The drawbacks of gelatin may be surmounted by synergistically combining it with a wide range of polysaccharides. The addition of polysaccharides to gelatin is advantageous in mimicking the ECM, which largely contains proteoglycans or glycoproteins. Moreover, gelatin-polysaccharide biomaterials benefit from mechanical resilience, high stability, low thermal expansion, improved hydrophilicity, biocompatibility, antimicrobial and anti-inflammatory properties, and wound healing potential. Here, we discuss how combining gelatin and polysaccharides provides a promising approach for developing superior therapeutic biomaterials. We review gelatin-polysaccharides scaffolds and their applications in cell culture and tissue engineering, providing an outlook for the future of this family of biomaterials as advanced natural therapeutics.

Overcoming Interfacial Scaling Using Engineered Nanocelluloses: A QCM-D Study

Nucleation of sparingly soluble species, such as the inorganic salts of calcium, magnesium, and phosphorous, followed by their growth at solid-liquid interfaces has turned into a major concern in water-based industries. Increased resistance against heat, mass, and momentum transfer is the main drawback of the so-called scaling phenomenon. Although phosphorous-, nitrogen-, and sulfur-based antiscaling macromolecules offer adequate antiscaling performance, their potential negative environmental impacts render them less desirable. Despite recent efforts in developing green antiscalants, there has been no promising green solution based on biomass due to its chemical inertness. Here, we use quartz crystal microbalance with dissipation monitoring (QCM-D) to evaluate the real-time performance of an emerging family of nanoengineered anionic hairy cellulose crystals, bearing dicarboxylated amorphous cellulose chains, with a charge density of more than 5.5 mequiv per g, in preventing the nucleation and growth of calcium carbonate, the most common industrial scale. Remarkably, a CaCO₃ mass deposition rate ∼0 (complete scale inhibition) is obtained when less than 10 ppm of the hairy nanocellulose is added to an already scaled surface under a harsh supersaturated condition at 50 °C. Motivated by their threshold antiscaling effect, we show that coating planar silica surfaces with hairy nanocelluloses may result in scale-resistant interfaces. This research envisions how engineered hairy nanocelluloses may have practical implications for developing scale-resistant interfaces based on the most abundant biopolymer in the world.

Periodate Oxidation Followed by NaBH4 Reduction Converts Microfibrillated Cellulose into Sterically Stabilized Neutral Cellulose Nanocrystal Suspensions

The periodate oxidation of microfibrillated cellulose followed by a reduction treatment was implemented to produce a new type of sterically stabilized cellulosic nanocrystals, which were characterized at the molecular and colloidal length scales. Solid-state NMR data showed that these treatments led to objects consisting of native cellulose and flexible polyols resulting from the oxidation and subsequent reduction of cellulose. A consistent set of data from dynamic light scattering, turbidimetry, transmission electron microscopy, and small-angle X-ray scattering experiments further showed that stable neutral elongated nanoparticles composed of a crystalline cellulosic core surrounded by a shell of dangling polyol chains were produced. The dimensions of these biosourced nanocrystals could be controlled by the degree of oxidation of the parent dialdehyde cellulose sample. The purely steric origin of the colloidal stability of these nanoparticles is a strong asset for their use under conditions where electrostatics no longer provides colloidal stability.

The influences of added polysaccharides on the properties of bacterial crystalline nanocellulose

Acid hydrolyzed bacterial crystalline nanocellulose (BCNC) with different nanofiber morphologies, geometrical dimensions, crystalline structure and mechanical properties were obtained by adding different polysaccharides into the growing culture medium. Arabinogalactan had little effect on the characteristics of BCNC due to its negligible binding affinity to bacterial cellulose (BC). Bacterial exopolysaccharides were capable of modulating the bundling of cellulose microfibrils during BC formation, resulting in BCNC with bundled nanocrystals, high crystallinity, a less sulfated surface, and improved thermal stability and tensile properties. Xylan/BCNC and xyloglucan/BCNC exhibited the most significant improvements, including an increased length and aspect ratio, a significantly less sulfated surface and superior thermal stability and tensile properties. It is hypothesized that the improvement in CNC characteristics results from a change in amorphous cellulose formation in the native BC. This study also suggests that improved feedstocks for producing CNCs may be obtained by modulating hemicellulose production in plants.

Nanocellulose as a sustainable biomass material: structure, properties, present status and future prospects in biomedical applications

Nanocellulose, extracted from the most abundant biomass material cellulose, has proved to be an environmentally friendly material with excellent mechanical performance owing to its unique nano-scaled structure, and has been used in a variety of applications as engineering and functional materials. The great biocompatibility and biodegradability, in particular, render nanocellulose promising in biomedical applications. In this review, the structure, treatment technology and properties of three different nanocellulose categories, i.e., nanofibrillated cellulose (NFC), nanocrystalline cellulose (NCC) and bacterial nanocellulose (BNC), are introduced and compared. The cytotoxicity, biocompatibility and frontier applications in biomedicine of the three nanocellulose categories were the focus and are detailed in each section. Future prospects concerning the cytotoxicity, applications and industrial production of nanocellulose are also discussed in the last section.

Squishy nanotraps: hybrid cellulose nanocrystal-zirconium metallogels for controlled trapping of biomacromolecules

A brick-and-mortar-like ultrasoft nanocomposite metallogel is formed by crosslinking cellulose nanocrystals (CNC) with ammonium zirconium carbonate (AZC) to trap and reconfigure dextran, a model biomacromolecule.