Self-Assembled Mucin-Containing Microcarriers via Hard Templating on CaCO₃ Crystals

Influence of natural polysaccharides on the morphology and properties of hybrid vaterite microcrystals

Co-precipitation of biopolymers into calcium carbonate crystals changes their physicochemical and biological properties. This work studies hybrid microcrystals of vaterite obtained in the presence of natural polysaccharides, as carriers for the delivery of proteins and enzymes. Hybrid microcrystals with dextran sulfate, chondroitin sulfate, heparin, fucoidan, and pectin were obtained and compared. The impact of polysaccharides on the morphology (particle diameter, surface area, nanocrystallite and pore size), polysaccharide content and surface charge of hybrid microcrystals was studied. Only microcrystals with fucoidan and heparin exhibited antioxidant activity against •ОН radical. The surface charge and pore size of the hybrid microcrystals affected the sorption of albumin, catalase, chymotrypsin, mucin. A decrease in the catalytic constant and Michaelis constant was observed for catalase sorbed on the hybrid crystals. The biocompatibility of microcrystals depended on the nature of the included polysaccharide: crystals with sulfated polysaccharides increased blood plasma coagulation but not platelet aggregation, and crystals with dextran sulfate had the greatest cytotoxicity against HT-29 cells but not erythrocytes. Hybrid microcrystals with all polysaccharides except chondroitin sulfate reduced erythrocyte lysis in vitro compared with vaterite crystals. The obtained results enable to create novel carriers based on hybrid vaterite crystals with polysaccharides, beneficial for the delivery of protein drugs.

Nanoarchitectonics of Bactericidal Coatings Based on CaCO3-Nanosilver Hybrids

Antimicrobial coatings provide protection against microbes colonization on surfaces. This can prevent the stabilization and proliferation of microorganisms. The ever-increasing levels of microbial resistance to antimicrobials are urging the development of alternative types of compounds that are potent across broad spectra of microorganisms and target different pathways. This will help to slow down the development of resistance and ideally halt it. The development of composite antimicrobial coatings (CACs) that can host and protect various antimicrobial agents and release them on demand is an approach to address this urgent need. In this work, new CACs based on microsized hybrids of calcium carbonate (CaCO3) and silver nanoparticles (AgNPs) were designed using a drop-casting technique. Polyvinylpyrrolidone and mucin were used as additives. The CaCO3/AgNPs hybrids contributed to endowing colloidal stability to the AgNPs and controlling their release, thereby ensuring the antibacterial activity of the coatings. Moreover, the additives PVP and mucin served as a matrix to (i) control the distribution of the hybrids, (ii) ensure mechanical integrity, and (iii) prevent the undesired release of AgNPs. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) techniques were used to characterize the 15 μm thick CAC. The antibacterial activity was determined against Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), and Pseudomonas aeruginosa, three bacteria responsible for many healthcare infections. Antibacterial performance of the hybrids was demonstrated at concentrations between 15 and 30 μg/cm2. Unloaded CaCO3 also presented bactericidal properties against MRSA. In vitro cytotoxicity tests demonstrated that the hybrids at bactericidal concentrations did not affect human dermal fibroblasts and human mesenchymal stem cell viability. In conclusion, this work presents a simple approach for the design and testing of advanced multicomponent and functional antimicrobial coatings that can protect active agents and release them on demand.

Snail extract for skin: A review of uses, projections, and limitations

BACKGROUND

Snail mucin is becoming increasingly popular for its wide range of ingredients and potential benefits. Snail extract's widespread appearance in cosmetic formulations encourages an investigation into the medical and cosmetic benefits.

AIMS

This study aims to explore current literature on the variety of snail mucin applications. Specifically, we present a review of the uses, global market estimates and projects, and limitations to snail mucin.

METHODS

A literature search was conducted on PubMed reviewing snail mucin and their application in medical and dermatologic fields examining their uses. Economic reports were also investigated for Global Market estimates.

RESULTS

The therapeutic use of snail mucin in medical fields has been studied as antimicrobial agents, drug delivery vehicles, antitumor agents, wound healing agents, and biomaterial coatings among others. Additionally, the use in cosmetic fields includes antiaging, hydrating, anti-acne, scarring, and hyperpigmentation treatments. It is important to highlight that most studies conducted were preclinical or small clinical studies, stressing the need for additional large-scale clinical trials to support these claims. Investigations into the global market found estimates ranging from $457 million to $1.2 billion with upward projections in the upcoming decade. Limitations include ethical habitats for collection, allergy investigation, and missing clinical studies.

CONCLUSIONS

The findings presented here emphasize the expanding uses of snail mucin and its ingredients alongside a growing market cosmetic industry should consider. We also emphasize the need for appropriate clinical trials into the stated benefits of snail mucin to ensure consumer safety and ethical extraction of mucin.

Incorporation of Pectin into Vaterite Microparticles Prevented Effects of Adsorbed Mucin on Neutrophil Activation

The application of vaterite microparticles for mucosal delivery depends on their interaction with mucin and immune cells. As we have shown previously, the binding of mucin onto particles enhances the generation of reactive oxygen species by neutrophils. The attenuation of the pro-oxidant effect of the bound mucin through the modification of vaterite could improve its biocompatibility. Hybrid microparticles composed of vaterite and pectin (CCP) were prepared using co-precipitation. In comparison with vaterite (CC), they had a smaller diameter and pores, a greater surface area, and a negative zeta-potential. We aimed to study the cytotoxicity and mucin-dependent neutrophil-activating effect of CCP microparticles. The incorporated pectin did not influence the neutrophil damage according to a lactate dehydrogenase test. The difference in the CC- and CCP-elicited luminol or lucigenin chemiluminescence of neutrophils was insignificant, with no direct pro- or antioxidant effects from the incorporated pectin. Unlike soluble pectin, the CCP particles were ineffective at scavenging radicals in an ABAP-luminol test. The fluorescence of SYTOX Green demonstrated a CCP-stimulated formation of neutrophil extracellular traps (NETs). The pre-treatment of CC and CCP with mucin resulted in a 2.5-times-higher CL response of neutrophils to the CC-mucin than to the CCP-mucin. Thus, the incorporation of pectin into vaterite microspheres enabled an antioxidant effect to be reached when the neutrophils were activated by mucin-treated microparticles, presumably via exposed ligands.

Exploiting Benefits of Vaterite Metastability to Design Degradable Systems for Biomedical Applications

The widespread application of calcium carbonate is determined by its high availability in nature and simplicity of synthesis in laboratory conditions. Moreover, calcium carbonate possesses highly attractive physicochemical properties that make it suitable for a wide range of biomedical applications. This review provides a conclusive analysis of the results on using the tunable vaterite metastability in the development of biodegradable drug delivery systems and therapeutic vehicles with a controlled and sustained release of the incorporated cargo. This manuscript highlights the nuances of vaterite recrystallization to non-porous calcite, dissolution at acidic pH, biodegradation at in vivo conditions and control over these processes. This review outlines the main benefits of vaterite instability for the controlled liberation of the encapsulated molecules for the development of biodegradable natural and synthetic polymeric materials for biomedical purposes.

Nanoarchitectonics beyond perfect order - not quite perfect but quite useful

Nanoarchitectonics, like architectonics, allows the design and building of structures, but at the nanoscale. Unlike those in architectonics, and even macro-, micro-, and atomic-scale architectonics, the assembled structures at the nanoscale do not always follow the projected design. In fact, they do follow the projected design but only for self-assembly processes producing structures with perfect order. Here, we look at nanoarchitectonics allowing the building of nanostructures without a perfect arrangement of building blocks. Here, fabrication of structures from molecules, polymers, nanoparticles, and nanosheets to polymer brushes, layer-by-layer assembly structures, and hydrogels through self-assembly processes is discussed, where perfect order is not necessarily the aim to be achieved. Both planar substrate and spherical template-based assemblies are discussed, showing the challenging nature of research in this field and the usefulness of such structures for numerous applications, which are also discussed here.

Activation of Neutrophils by Mucin–Vaterite Microparticles

Nano- and microparticles enter the body through the respiratory airways and the digestive system, or form as biominerals in the gall bladder, salivary glands, urinary bladder, kidney, or diabetic pancreas. Calcium, magnesium, and phosphate ions can precipitate from biological fluids in the presence of mucin as hybrid nanoparticles. Calcium carbonate nanocrystallites also trap mucin and are assembled into hybrid microparticles. Both mucin and calcium carbonate polymorphs (calcite, aragonite, and vaterite) are known to be components of such biominerals as gallstones which provoke inflammatory reactions. Our study was aimed at evaluation of neutrophil activation by hybrid vaterite–mucin microparticles (CCM). Vaterite microparticles (CC) and CCM were prepared under standard conditions. The diameter of CC and CCM was 3.3 ± 0.8 µm and 5.8 ± 0.7 µm, with ƺ-potentials of −1 ± 1 mV and −7 ± 1 mV, respectively. CC microparticles injured less than 2% of erythrocytes in 2 h at 1.5 mg mL−1, and no hemolysis was detected with CCM; this let us exclude direct damage of cellular membranes by microparticles. Activation of neutrophils was analyzed by luminol- and lucigenin-dependent chemiluminescence (Lum-CL and Luc-CL), by cytokine gene expression (IL-6, IL-8, IL-10) and release (IL-1β, IL-6, IL-8, IL-10, TNF-α), and by light microscopy of stained smears. There was a 10-fold and higher increase in the amplitude of Lum-CL and Luc-CL after stimulation of neutrophils with CCM relative to CC. Adsorption of mucin onto prefabricated CC microparticles also contributed to activation of neutrophil CL, unlike mucin adsorption onto yeast cell walls (zymosan); adsorbed mucin partially suppressed zymosan-stimulated production of oxidants by neutrophils. Preliminary treatment of CCM with 0.1–10 mM NaOCl decreased subsequent activation of Lum-CL and Luc-CL of neutrophils depending on the used NaOCl concentration, presumably because of the surface mucin oxidation. Based on the results of ELISA, incubation of neutrophils with CCM downregulated IL-6 production but upregulated that of IL-8. IL-6 and IL-8 gene expression in neutrophils was not affected by CC or CCM according to RT2-PCR data, which means that post-translational regulation was involved. Light microscopy revealed adhesion of CC and CCM microparticles onto the neutrophils; CCM increased neutrophil aggregation with a tendency to form neutrophil extracellular traps (NETs). We came to the conclusion that the main features of neutrophil reaction to mucin–vaterite hybrid microparticles are increased oxidant production, cell aggregation, and NET-like structure formation, but without significant cytokine release (except for IL-8). This effect of mucin is not anion-specific since particles of powdered kidney stone (mainly calcium oxalate) in the present study or calcium phosphate nanowires in our previous report also activated Lum-CL and Luc-CL response of neutrophils after mucin sorption.

Calcium carbonate vaterite particles for drug delivery: Advances and challenges

The recent successful application of lipid-based nanoparticles as delivery vehicles in COVID-19 vaccines demonstrated the superior potential of nanoparticle-based technology for targeted drug delivery in biomedicine. Among novel, rapidly advancing delivery platforms, the inorganic nano/microparticles gradually reach new heights and attract well-deserved attention among scientists and clinicians. Calcium carbonate in its vaterite form is used as a biocompatible carrier for a progressively increasing number of biomedical applications. Its growing popularity is conferred by beneficial porosity of particles, high mechanical stability, biodegradability under certain physiological conditions, ability to provide a continuous steady release of bioactives, preferential safety profile, and low cost, which make calcium carbonate a suitable entity of highly efficacious formulations for controlled drug delivery and release. The focal point of the current review is the success of the recent vaterite applications in the delivery of various diagnostics and therapeutic drugs. The manuscript highlights the nuances of drug loading in vaterite particles, connecting it with particle morphology, size, and charge of the loaded molecules, payload concentration, mono- or multiple drug loading. The manuscript also depicts recent successful methods of increasing the loading capacity developed for vaterite carriers. In addition, the review describes the various administration routes for vaterite particles with bioactive payloads, which were reported in recent years. Special attention is given to the multi-drug-loaded vaterite particles ("molecular cocktails") and reports on their successful delivery in vitro and in vivo.

Hybrid Mucin-Vaterite Microspheres for Delivery of Proteolytic Enzyme Chymotrypsin

While the enteral delivery of proteolytic enzymes is widely established for combating many diseases as an alternative to antibiotic treatment, their local delivery only emerges as administration route enabling sustained release in a controlled manner on site. The latest requires the development of drug delivery systems suitable for encapsulation and preservation of enzymatic proteolytic activity. This study proposes hybrid microspheres made of mucin and biodegradable porous crystals of calcium carbonate (CC) as the carriers for chymotrypsin (CTR) delivery. CTR was impregnated into CC and hybrid CC/mucin (CCM) microspheres by means of sorption without any chemical modification. The loading of the CC with mucin enhances CTR retention on hybrid microspheres (adsorption capacity of ca 8.7 versus 4.7 mg/g), recharging crystal surface due to the presence of mucin and diminishing the average pore diameter of the crystals from 25 to 8 nm. Mucin also retards recrystallization of vaterite into non-porous calcite improving stability of CCM microspheres upon storage. Proteolytic activity of CTR is preserved in both CC and CCM microspheres, being pH dependent. Temperature-induced inactivation of CTR significantly diminishes by CTR encapsulation into CC and CCM microspheres. Altogether, these findings indicate promises of hybrid mucin-vaterite microspheres for mucosal application of proteases. This article is protected by copyright. All rights reserved.

A comparative evaluation of layer-by-layer assembly techniques for surface modification of microcarriers used in human mesenchymal stromal cell manufacturing

The demand for large quantities of highly potent human mesenchymal stromal cells (hMSCs) is growing given their therapeutic potential. To meet high production needs, suspension-based cell cultures using microcarriers are commonly used. Microcarriers are commonly made of or coated with extracellular matrix proteins or charged compounds to promote cell adhesion and proliferation. In this work, we demonstrate a simple method (draining filter) to perform layer by layer (LbL) assembly on microcarriers to create multilayers of heparin and collagen and further demonstrate that these multilayers have a positive effect on hMSC viability after 48 hours of culture. The draining filter method is evaluated against two other methods found in literature - centrifugation and fluidized bed, showing that the draining filter method can perform the surface modification with greater efficiency and with less materials and steps needed in the coating process. This article is protected by copyright. All rights reserved.

Modification of Surfaces with Vaterite CaCO3 Particles

Former studies have demonstrated a strong interest toward the crystallization of CaCO3 polymorphs in solution. Nowadays, CaCO3 crystallization on solid surfaces is extensively being studied using biomolecules as substrates for the control of the growth aiming at various applications of CaCO3. Calcium carbonate exists in an amorphous state, as three anhydrous polymorphs (aragonite, calcite and vaterite), and as two hydrated polymorphs (monohydrocalcite and ikaite). The vaterite polymorph is considered as one of the most attractive forms due to its large surface area, biocompatibility, mesoporous nature, and other features. Based on physical or chemical immobilization approaches, vaterite can be grown directly on solid surfaces using various (bio)molecules, including synthetic polymers, biomacromolecules such as proteins and peptides, carbohydrates, fibers, extracellular matrix components, and even biological cells such as bacteria. Herein, the progress on the modification of solid surfaces by vaterite CaCO3 crystals is reviewed, focusing on main findings and the mechanism of vaterite growth initiated by various substances mentioned above, as well as the discussion of the applications of such modified surfaces.

Stimulation Of Neutrophil Oxidative Burst By Calcium Phosphate Particles With Adsorbed Mucin

Objective — Mucin can promote formation of gallstones via precipitation with calcium phosphate. The proinflammatory effect of mucin-coated particles is still unclear, and our aim was to study the role of mucin sorption in activation of neutrophil respiratory burst. Material and Methods — Polydisperse calcium phosphate nanowires (CP) were prepared from hot gelatin solution and according to scanning electron microscopy (SEM) had the length 1-10 μm and thickness 50-450 nm. CP were incubated in mucin or human serum albumin (HSA) giving CP-Muc and CP-HSA. Their hemolytic activity towards human erythrocytes was assayed, and neutrophil lucigenin- and luminol- chemiluminescence (Luc-CL and Lum-CL) response to CP, CP-HSA and CP-Muc was measured. Cytokine RNA was detected in neutrophils by means of reverse transcription with subsequent real-time PCR. Cytokines (IL-1β, IL-6, IL-8, IL-10) were assessed in cell medium by ELISA. Results and Conclusion — Hemolytic activity of CP was 3.0±0.5%, mucin sorption (0.019 mg/mg) reduced it to 0.24±0.04% (p<0.05) as well as HSA. CP and CP-HSA stimulated neutrophil Lum-CL and Luc-Cl by 2-3 times vs. spontaneous values while for CP-Muc the effect was 10-fold and higher. No increased cytokine gene expression or cytokine secretion was detected after 1h incubation of neutrophils with samples. Obviously, sorption of mucin but not that of HSA stimulated generation of reactive oxygen and halogen species with no increase in cytokine production. Thus, the mucin-coated CP has the potential to contribute to gallstone-associated cholecystitis via oxidative damage of mucosa and epithelium.

Purified mucins in drug delivery research

One of the main challenges in the field of drug delivery remains the development of strategies to efficiently transport pharmaceuticals across mucus barriers, which regulate the passage and retention of molecules and particles in all luminal spaces of the body. A thorough understanding of the molecular mechanisms, which govern such selective permeability, is key for achieving efficient translocation of drugs and drug carriers. For this purpose, model systems based on purified mucins can contribute valuable information. In this review, we summarize advances that were made in the field of drug delivery research with such mucin-based model systems: First, we give an overview of mucin purification procedures and discuss the suitability of model systems reconstituted from purified mucins to mimic native mucus. Then, we summarize techniques to study mucin binding. Finally, we highlight approaches that made use of mucins as building blocks for drug delivery platforms or employ mucins as active compounds.

Advancing Discovery of Snail Mucins Function and Application

Mucins are a highly glycosylated protein family that are secreted by animals for adhesion, hydration, lubrication, and other functions. Despite their ubiquity, animal mucins are largely uncharacterized. Snails produce mucin proteins in their mucous for a wide array of biological functions, including microbial protection, adhesion and lubrication. Recently, snail mucins have also become a lucrative source of innovation with wide ranging applications across chemistry, biology, biotechnology, and biomedicine. Specifically, snail mucuses have been applied as skin care products, wound healing agents, surgical glues, and to combat gastric ulcers. Recent advances in integrated omics (genomic, transcriptomic, proteomic, glycomic) technologies have improved the characterization of gastropod mucins, increasing the generation of novel biomaterials. This perspective describes the current research on secreted snail mucus, highlighting the potential of this biopolymer, and also outlines a research strategy to fulfill the unmet need of examining the hierarchical structures that lead to the enormous biological and chemical diversity of snail mucus genes.

Biopolymer-Based Multilayer Capsules and Beads Made via Templating: Advantages, Hurdles and Perspectives

One of the undeniable trends in modern bioengineering and nanotechnology is the use of various biomolecules, primarily of a polymeric nature, for the design and formulation of novel functional materials for controlled and targeted drug delivery, bioimaging and theranostics, tissue engineering, and other bioapplications. Biocompatibility, biodegradability, the possibility of replicating natural cellular microenvironments, and the minimal toxicity typical of biogenic polymers are features that have secured a growing interest in them as the building blocks for biomaterials of the fourth generation. Many recent studies showed the promise of the hard-templating approach for the fabrication of nano- and microparticles utilizing biopolymers. This review covers these studies, bringing together up-to-date knowledge on biopolymer-based multilayer capsules and beads, critically assessing the progress made in this field of research, and outlining the current challenges and perspectives of these architectures. According to the classification of the templates, the review sequentially considers biopolymer structures templated on non-porous particles, porous particles, and crystal drugs. Opportunities for the functionalization of biopolymer-based capsules to tailor them toward specific bioapplications is highlighted in a separate section.

Aerosol-based antimicrobial photoinactivation in the lungs: an action spectrum study

Chronic lung infections are among the most diffused human infections, being often associated with multidrug-resistant bacteria. In this framework, the European project "Light4Lungs" aims at synthesizing and testing an inhalable light source to control lung infections by antimicrobial photoinactivation (aPDI), addressing endogenous photosensitizers only (porphyrins) in the representative case of S. aureus and P. aeruginosa. In the search for the best emission characteristics for the aerosolized light source, this work defines and calculates the photo-killing action spectrum for lung aPDI in the exemplary case of cystic fibrosis. This was obtained by applying a semi-theoretical modelling with Monte Carlo simulations, according to previously published methodology related to stomach infections and applied to the infected trachea, bronchi, bronchioles and alveoli. In each of these regions, the two low and high oxygen concentration cases were considered to account for the variability of in vivo conditions, together with the presence of endogenous porphyrins and other relevant absorbers/diffusers inside the illuminated biofilm/mucous layer. Furthermore, an a priori method to obtain the "best illumination wavelengths" was defined, starting from maximizing porphyrin and light absorption at any depth. The obtained action spectrum is peaked at 394 nm and mostly follows porphyrin extinction coefficient behavior. This is confirmed by the results from the best illumination wavelengths, which reinforces the robustness of our approach. These results can offer important indications for the synthesis of the aerosolized light source and definition of its most effective emission spectrum, suggesting a flexible platform to be considered in further applications.

CaCO3 crystals as versatile carriers for controlled delivery of antimicrobials

CaCO₃ crystals have been known for a long time as naturally derived and simply fabricated nano(micro)-sized materials able to effectively host and release various molecules. This review summarises the use of CaCO₃ crystals as versatile carriers to host, protect and release antimicrobials, offering a strong tool to tackle antimicrobial resistance, a serious global health problem. The main methods for the synthesis of CaCO₃ crystals with different properties, as well as the approaches for the loading and release of antimicrobials are presented. Finally, prospects to utilize the crystals in order to improve the therapeutic outcome and combat antimicrobial resistance are highlighted. Ultimately, this review intends to provide an in-depth overview of the application of CaCO₃ crystals for the smart and controlled delivery of antimicrobial agents and aims at identifying the advantages and drawbacks as well as guiding future works, research directions and industrial applications.

Interactions of microorganisms with host mucins: a focus on Candida albicans

Mucus is an important host innate defense factor that lines most epithelial cell layers of the body and provides crucial physical and biological protection against pathogenic microorganisms. Mucins are the main glycoproteins of mucus that are responsible for interacting with microorganisms and are critical for the antimicrobial properties of mucus. The mechanisms by which microorganisms interact with mucins are poorly understood, especially in terms of fungi, and these interactions are continually evolving. Work in bacterial pathogens has shown that mucins inhibit bacterial virulence traits, including quorum sensing, toxin secretion and biofilm formation. Among the fungal clade, the common opportunistic human fungal pathogen and commensal Candida albicans engages in constant battle with the host innate immune system. This battle creates strong selective pressures for C. albicans to evolve in response to the host. Recent work in C. albicans found that mucins inhibit specific virulence traits, such as surface adherence, filamentation, biofilm formation and the production of secreted proteases. Here we review the current knowledge of microbial interactions with mucins, with a special emphasis on the interactions between C. albicans and mucins.

Layer-By-Layer Assemblies of Biopolymers: Build-Up, Mechanical Stability and Molecular Dynamics

Rapid development of versatile layer-by-layer technology has resulted in important breakthroughs in the understanding of the nature of molecular interactions in multilayer assemblies made of polyelectrolytes. Nowadays, polyelectrolyte multilayers (PEM) are considered to be non-equilibrium and highly dynamic structures. High interest in biomedical applications of PEMs has attracted attention to PEMs made of biopolymers. Recent studies suggest that biopolymer dynamics determines the fate and the properties of such PEMs; however, deciphering, predicting and controlling the dynamics of polymers remains a challenge. This review brings together the up-to-date knowledge of the role of molecular dynamics in multilayers assembled from biopolymers. We discuss how molecular dynamics determines the properties of these PEMs from the nano to the macro scale, focusing on its role in PEM formation and non-enzymatic degradation. We summarize the factors allowing the control of molecular dynamics within PEMs, and therefore to tailor polymer multilayers on demand.

Polyelectrolyte Multilayer Capsule (PEMC)-Based Scaffolds for Tissue Engineering

Tissue engineering (TE) is a highly multidisciplinary field that focuses on novel regenerative treatments and seeks to tackle problems relating to tissue growth both in vitro and in vivo. These issues currently involve the replacement and regeneration of defective tissues, as well as drug testing and other related bioapplications. The key approach in TE is to employ artificial structures (scaffolds) to support tissue development; these constructs should be capable of hosting, protecting and releasing bioactives that guide cellular behaviour. A straightforward approach to integrating bioactives into the scaffolds is discussed utilising polyelectrolyte multilayer capsules (PEMCs). Herein, this review illustrates the recent progress in the use of CaCO3 vaterite-templated PEMCs for the fabrication of functional scaffolds for TE applications, including bone TE as one of the main targets of PEMCs. Approaches for PEMC integration into scaffolds is addressed, taking into account the formulation, advantages, and disadvantages of such PEMCs, together with future perspectives of such architectures.

Encapsulation of Low-Molecular-Weight Drugs into Polymer Multilayer Capsules Templated on Vaterite CaCO3 Crystals

Polyelectrolyte multilayer capsules (PEMCs) templated onto biocompatible and easily degradable vaterite CaCO₃ crystals via the layer-by-layer (LbL) polymer deposition process have served as multifunctional and tailor-made vehicles for advanced drug delivery. Since the last two decades, the PEMCs were utilized for effective encapsulation and controlled release of bioactive macromolecules (proteins, nucleic acids, etc.). However, their capacity to host low-molecular-weight (LMW) drugs (<1–2 kDa) has been demonstrated rather recently due to a limited retention ability of multilayers to small molecules. The safe and controlled delivery of LMW drugs plays a vital role for the treatment of cancers and other diseases, and, due to their tunable and inherent properties, PEMCs have shown to be good candidates for smart drug delivery. Herein, we summarize recent progress on the encapsulation of LMW drugs into PEMCs templated onto vaterite CaCO₃ crystals. The drug loading and release mechanisms, advantages and limitations of the PEMCs as LMW drug carriers, as well as bio-applications of drug-laden capsules are discussed based upon the recent literature findings.

Inter-protein interactions govern protein loading into porous vaterite CaCO3 crystals

Loading of therapeutic proteins into mesoporous vaterite crystals is driven by inter-protein interactions in bulk solution and inside the crystals.

Naturally derived nano- and micro-drug delivery vehicles: halloysite, vaterite and nanocellulose

We discuss prospects for halloysite nanotubes, vaterite crystals and nanocellulose to enter the market of biomaterials for drug delivery and tissue engineering, and their potential for economically viable production from abundant natural sources.

Mucin adsorbed by E. coli can affect neutrophil activation in vitro

Bacteria colonizing human intestine adhere to the gut mucosa and avoid the innate immune system. We previously demonstrated that Escherichia coli isolates can adsorb mucin from a diluted solution in vitro. Here, we evaluated the effect of mucin adsorption by E. coli cells on neutrophil activation in vitro. Activation was evaluated based on the detection of reactive oxygen species production by a chemiluminescent reaction (ChL), observation of morphological alterations in neutrophils and detection of exocytosis of myeloperoxidase and lactoferrin. We report that mucin adsorbed by cells of SharL1 isolate from Crohn's disease patient's inflamed ileum suppressed the potential for the activation of neutrophils in whole blood. Also, the binding of plasma complement proteins and immunoglobulins to the bacteria was reduced. Desialylated mucin, despite having the same adsorption efficiency to bacteria, had no effect on the blood ChL response. The effect of mucin suggests that it shields epitopes that interact with neutrophils and plasma proteins on the bacterial outer membrane. Potential candidates for these epitopes were identified among the proteins within the bacterial outer membrane fraction by 2D‐PAGE, fluorescent mucin binding on a blot and HPLC‐MS/MS. In vitro, the following proteins demonstrated mucin adsorption: outer membrane porins (OmpA, OmpC, OmpD and OmpF), adhesin OmpX, the membrane assembly factor OmpW, cobalamine transporter, ferrum uptake protein and the elongation factor Ef Tu‐1. In addition to their other functions, these proteins are known to be bacterial surface antigens. Therefore, the shielding of epitopes by mucin may affect the dynamics and intensity of an immune response.

Porous Alginate Scaffolds Assembled Using Vaterite CaCO3 Crystals

Formulation of multifunctional biopolymer-based scaffolds is one of the major focuses in modern tissue engineering and regenerative medicine. Besides proper mechanical/chemical properties, an ideal scaffold should: (i) possess a well-tuned porous internal structure for cell seeding/growth and (ii) host bioactive molecules to be protected against biodegradation and presented to cells when required. Alginate hydrogels were extensively developed to serve as scaffolds, and recent advances in the hydrogel formulation demonstrate their applicability as "ideal" soft scaffolds. This review focuses on advanced porous alginate scaffolds (PAS) fabricated using hard templating on vaterite CaCO3 crystals. These novel tailor-made soft structures can be prepared at physiologically relevant conditions offering a high level of control over their internal structure and high performance for loading/release of bioactive macromolecules. The novel approach to assemble PAS is compared with traditional methods used for fabrication of porous alginate hydrogels. Finally, future perspectives and applications of PAS for advanced cell culture, tissue engineering, and drug testing are discussed.

Development of Bioelectronic Devices Using Bionanohybrid Materials for Biocomputation System

Bioelectronic devices have been researched widely because of their potential applications, such as information storage devices, biosensors, diagnosis systems, organism-mimicking processing system cell chips, and neural-mimicking systems. Introducing biomolecules including proteins, DNA, and RNA on silicon-based substrates has shown the powerful potential for granting various functional properties to chips, including specific functional electronic properties. Until now, to extend and improve their properties and performance, organic and inorganic materials such as graphene and gold nanoparticles have been combined with biomolecules. In particular, bionanohybrid materials that are composed of biomolecules and other materials have been researched because they can perform core roles of information storage and signal processing in bioelectronic devices using the unique properties derived from biomolecules. This review discusses bioelectronic devices related to computation systems such as biomemory, biologic gates, and bioprocessors based on bionanohybrid materials with a selective overview of recent research. This review contains a new direction for the development of bioelectronic devices to develop biocomputation systems using biomolecules in the future.

Mucin adsorption on vaterite CaCO3 microcrystals for the prediction of mucoadhesive properties

Porous vaterite CaCO₃ crystals are widely used as containers for drug loading and as sacrificial templates to assemble polymer-based nano- and micro-particles at mild conditions. Special attention is paid nowadays to mucosal delivery where the glycoprotein mucin plays a crucial role as a main component of a mucous. In this work mucoadhesive properties of vaterite crystals have been tested by investigation of mucin binding to the crystals as a function of (i) time, (ii) glycoprotein concentration, (iii) adsorption conditions and (iv) degree of mucin desialization. Mucin adsorption follows Bangham equation indicating that diffusion into crystal pores is the rate-limiting step. Mucin strongly binds to the crystals (ΔG = -35 ± 4 kJ mol^-1) via electrostatic and hydrophobic interactions forming a gel and thus giving the tremendous mucin mass content in the crystals of up to 16%. Despite strong intermolecular mucin-mucin interactions, pure mucin spheres formed after crystal dissolution are unstable. However, introduction of protamine, actively used for mucosal delivery, makes the spheres stable via additional electrostatic bonding. The results of this work indicate that the vaterite crystals are extremely promising carriers for mucosal drug delivery and for development of test-systems for the analysis of the mucoadhesion.

Internal Structure of Matrix-Type Multilayer Capsules Templated on Porous Vaterite CaCO₃ Crystals as Probed by Staining with a Fluorescence Dye

Multilayer capsules templated on decomposable vaterite CaCO₃ crystals are widely used as vehicles for drug delivery. The capsule represents typically not a hollow but matrix-like structure due to polymer diffusion into the porous crystals during multilayer deposition. The capsule formation mechanism is not well-studied but its understanding is crucial to tune capsule structure for a proper drug release performance. This study proposes new approach to noninvasively probe and adjust internal capsule structure. Polymer capsules made of poly(styrene-sulfonate) (PSS) and poly(diallyldimethylammonium chloride) (PDAD) have been stained with fluorescence dye rhodamine 6G. Physical-chemical aspects of intermolecular interactions required to validate the approach and adjust capsule structure are addressed. The capsules consist of a defined shell (typically 0.5⁻2 µm) and an internal matrix of PSS-PDAD complex (typically 10⁻40% of a total capsule volume). An increase of ionic strength and polymer deposition time leads to the thickening of the capsule shell and formation of a denser internal matrix, respectively. This is explained by effects of a polymer conformation and limitations in polymer diffusion through the crystal pores. We believe that the design of the capsules with desired internal structure will allow achieving effective encapsulation and controlled/programmed release of bioactives for advanced drug delivery applications.