Halloysite- and Montmorillonite-Loaded Scaffolds as Enhancers of Chronic Wound Healing

Smart copper-doped clays in biomimetic microparticles for wound healing and infection control

Chronic wounds are non-healing lesions characterized by a high degree of inflammation, posing significant challenges in clinical management due to the increased risk of severe infection. This study focuses on developing a powder for cutaneous application to enhance the healing and prevent infections in chronic wounds. The smart nanocomposites-based biomimetic microparticles here developed combine the properties of chitosan and of clays and represent a significant innovation in the field of biomaterials for skin regeneration since they possess enhanced antimicrobial properties, are multi-functional scaffolds and promote cell proliferation, support tissue reconstruction by mimicking the natural extracellular matrix, and provide hemostatic properties to control bleeding during wound closure. The microparticles were made of chitosan and doped with clay minerals, specifically montmorillonite or layered double hydroxides, containing copper ions. The synergistic combination of biomimetic polymers and clays aims to regulate cellular responses, angiogenesis, and extracellular matrix (ECM) deposition, leveraging the bioactive properties of both components to promote wound healing. Montmorillonite and layered double hydroxides were enriched with copper ions through intercalation or coprecipitation methods, respectively. The water-insoluble microparticles were prepared using a chitosan derivative, chitosan carbamate, synthesized to obtain chitosan-based microparticles via spray-drying without crosslinkers. Physico-chemical characterization confirmed the successful doping of Cu-clay interaction products in the microparticles. In addition to enhanced cell proliferation and hemostatic properties, the presence of Cu-clays boosted the microparticles' antibacterial properties. Encouraging preclinical in vitro and in vivo results suggest that these smart nanocomposite biomimetic microparticles doped with Cu-enriched clay minerals could be promising candidates for simultaneously enhancing healing and controlling infections in chronic wounds.

The potential cutaneous benefits of bentonites and montmorillonites

Bentonites and montmorillonites, natural clay minerals originating from volcanic ash, possess unique properties that have traditionally been utilized in industrial applications. Recently, their potential biomedical applications, particularly in dermatology, have garnered significant interest. This review explores the cutaneous benefits of bentonites and montmorillonites, highlighting their anti-inflammatory, wound-healing, oil-absorbing, drug delivery, photoprotective, and anti-aging effects. Evidence from in vitro experiments, animal studies, and preliminary clinical trials demonstrate that these clays can significantly reduce inflammation, accelerate wound healing, absorb excess oil, enhance drug delivery, protect against ultraviolet radiation, and improve skin hydration and elasticity. Larger scale randomized clinical trials (RCTs) are needed to further establish the safety and efficacy of bentonites and montmorillonites. Given the increasing consumer demand for natural ingredients in skincare, bentonites and montmorillonites present a promising area for further research and development in dermatologic applications.

Incorporation of montmorillonite into microfluidics-generated chitosan microfibers enhances neuron-like PC12 cells for application in neural tissue engineering

The complexity in structure and function of the nervous system, as well as its slow rate of regeneration, makes it more difficult to treat it compared to other tissues. Neural tissue engineering aims to create an appropriate environment for nerve cell proliferation and differentiation. Fibrous scaffolds with suitable morphology and topography and better mimicry of the extracellular matrix have been promising for the alignment and migration of neural cells. On this premise, to improve the properties of the scaffold, we combined montmorillonite (MMT) with chitosan (CS) polymer and created microfibers with variable diameters and varied concentrations of MMT using microfluidic technology and tested its suitability for the rat pheochromocytoma cell line (PC12). According to the findings, CS/MMT 0.1 % compared to CS/MMT 0 % microfibers showed a 201 MPa increase in Young's modulus, a 68 mS/m increase in conductivity, and a 1.4-fold increase in output voltage. Analysis of cell mitochondrial activity verified the non-toxicity, resulting in good cell morphology with orientation along the microfiber. Overall, the results of this project showed that with a low concentration of MMT, the properties of microfibers can be significantly improved and a suitable scaffold can be designed for neural tissue engineering.

Development and characterization of three-dimensional antibacterial nanocomposite sponges of chitosan, silver nanoparticles and halloysite nanotubes

In this work, we developed novel nanocomposite three-dimensional (3D) scaffolds composed of chitosan (CTS), halloysite nanotubes (HNTs) and silver nanoparticles (AgNPs) with enhanced antimicrobial activity and fibroblast cell compatibility for their potential use in wound dressing applications. A stock CTS-HNT solution was obtained by mixing water-dispersed HNTs with CTS aqueous-acid solution, and then, AgNPs, in different concentrations, were synthesized in the CTS-HNT solution via a CTS-mediated in situ reduction method. Finally, freeze-gelation was used to obtain CTS-HNT-AgNP 3D porous scaffolds (sponges). Morphology analysis showed that synthesized AgNPs were spherical with an average diameter of 11 nm. HNTs' presence did not affect the AgNPs morphology or size but improved the mechanical properties of the scaffolds, where CTS-HNT sponges exhibited a 5 times larger compression stress than bare-CTS sponges. AgNPs in the scaffolds further increased their mechanical strength in correlation to the AgNP concentration, and conferred them improved antibacterial activity against Gram-negative and Gram-positive bacteria, inhibiting the planktonic proliferation and adhesion of bacteria in a AgNP concentration depending on manner. In vitro cell viability and immunofluorescence assays exhibited that human fibroblast (HF) culture was supported by the sponges, where HF retained their phenotype upon culture on the sponges. Present CTS-HNT-AgNP sponges showed promising mechanical, antibacterial and cytocompatibility properties to be used as potential scaffolds for wound dressing applications.

The Horizons of Medical Mineralogy: Structure-Bioactivity Relationship and Biomedical Applications of Halloysite Nanoclay

Medical mineralogy explores the interactions between natural minerals and living organisms such as cells, tissues, and organs and develops therapeutic and diagnostic applications in drug delivery, medical devices, and healthcare materials. Many minerals (especially clays) have been recognized for pharmacological activities and therapeutic potential. Halloysite clay (Chinese medicine name: Chishizhi), manifested as one-dimensional aluminum silicate nanotubes (halloysite nanotubes, HNTs), has gained applications in hemostasis, wound repair, gastrointestinal diseases, tissue engineering, detection and sensing, cosmetics, and daily chemicals formulations. Various biomedical applications of HNTs are derived from hollow tubular structures, high mechanical strength, good biocompatibility, bioactivity, and unique surface characteristics. This natural nanomaterial is safe, abundantly available, and may be processed with environmentally safe green chemistry methods. This review describes the structure and physicochemical properties of HNTs relative to bioactivity. We discuss surface area, porosity and surface defects, hydrophilicity, heterogeneity and charge of external and internal surfaces, as well as biosafety. The paper provides comprehensive guidance for the development of this tubule nanoclay and its advanced biomedical applications for clinical diagnosis and therapy.

Multifunctional Nanoclay-Based Hemostatic Materials for Wound Healing: A Review

Bleeding to death accounts for around 30-40% of all trauma-related fatalities. Current hemostatic materials are mainly mono-functional or have insufficient hemostatic capacity. Nanoclay has been recently shown to accelerate hemostasis, improve wound healing, and provide the resulting multifunctional hemostatic materials antibacterial, anti-inflammatory, and healing-promoting due to its distinctive morphological structure and physicochemical properties. Herein, the chemical design and action mechanism of nanoclay-based hemostatic, antibacterial, and pro-wound healing materials in the context of wound healing are discussed. The physiological processes of hemostasis and wound healing to elucidate the significance of nanoclay for functional wound hemostatic dressing design are outlined. A summary of the features of various nanoclay and product types used in wound hemostatic dressings is provided. Nanoclay can be antimicrobial due to the slow release of metal ions and has an abundant surface charge allowing for high affinity for proteins and cells, which can activate the coagulation reaction or facilitate tissue repair. Nanoclay with a microporous structure can be used as drug carriers to create composites critical for inhibiting bacterial growth on wounds or promoting the regeneration of vascular, muscle, and skin tissues. Directions for further research and innovation of nanoclay-based multifunctional materials for hemostasis and tissue regeneration are explored.

Nanoclay-Doped Electrospun Nanofibers for Tissue Engineering: Investigation on the Structural Modifications in Physiological Environment

Background

Clay minerals are nanomaterials that have recently been recognized as enabling excipients that can promote cell adhesion, proliferation, and differentiation. When nanoclays are loaded in a 3D polymeric nanostructure, the cell-substrate interaction is enhanced, and other bioactive properties are optimized.

Purpose

In this study, hectorite (HEC)- and montmorillonite (MMT)-doped polymeric scaffolds were explored for the treatment of deep and chronic skin lesions.

Methods

Scaffolds were manufactured by means of electrospinning and then crosslinked by heating. Physicochemical analyses were correlated with in vitro biopharmaceutical characterization to predict the in vivo fate of the clay-doped scaffolds.

Results and Discussion

The addition of MMT or HEC to the polymeric scaffold framework modifies the surface arrangement and, consequently, the potential of the scaffolds to interact with biological proteins. The presence of nanoclays alters the nanofiber morphology and size, and MMT doping increases wettability and protein adhesion. This has an impact on fibroblast behavior in a shorter time since scaffold stiffness facilitates cell adhesion and cell proliferation.

Conclusion

MMT proved to perform better than HEC, and this could be related to its higher hydrophilicity and protein adhesion.

Design and development of polydioxanone scaffolds for skin tissue engineering manufactured via green process

Fiber spinning technologies attracted a great interest since the beginning of the last century. Among these, electrospinning is a widely diffuse technique; however, it presents some drawbacks such as low fiber yield, high energy demand and the use of organic solvents. On the contrary, centrifugal spinning is a more sustainable method and allows to obtain fiber using centrifugal force and melted materials. The aim of the present work was the design and the development of polydioxanone (PDO) microfibers intended for tissue engineering, using centrifugal spinning. PDO, a bioresorbable polymer currently used for sutures, was selected as low melting polyester and DES (deep eutectic solvents), either choline chloride/citric acid (ChCl/CA) or betaine/citric acid (Bet/CA) 1:1 M ratio, were used to improve PDO spinnability. Physical mixtures of DES and PDO were prepared using different weight ratios. These were then poured into the spinneret and melted at 140 °C for 5 min. After the complete melting, the blends were spun for 1 min at 700 rpm. The fibers were characterized for physico chemical properties (morphology; dimensions; chemical structure; thermal behavior; mechanical properties). Moreover, the preclinical investigation was performed in vitro (biocompatibility, adhesion and proliferation of fibroblasts) and in vivo (murine burn/excisional model to assess safety and efficacy). The multidisciplinary approach allowed to obtain an extensive characterization to develop PDO based microfibers as medical device for implant to treat full thickness skin wounds.

Functionally modified halloysite nanotubes for personalized bioapplications

Halloysite nanotubes (HNTs) are naturally aluminosilicate clay minerals that have the benefits of large surface areas, high mechanical properties, easy functionalization, and high biocompatibility, HNTs have been developed as multifunctional nanoplatforms for various bioapplications. Although some reviews have summarized the properties and bioapplications of HNTs, it remains unclear how to functionalize the modifications of HNTs for their personalized bioapplications. In this review, based on the physicochemical properties of HNTs, we summarized the methods of functionalized modifications (surface modification and structure modification) on HNTs. Also, we highlighted their personalized bioapplications (anti-bacterial, anti-inflammatory, wound healing, cancer theranostics, bone regenerative, and biosensing) by stressing on the main roles of HNTs. Finally, we provide perspectives on the future of functionalized modifications of HNTs for docking specific biological applications.

Nanoclays in medicine: a new frontier of an ancient medical practice

Clays have been used as early as 2500 BC in human civilization for medicinal purposes. The ease of availability, biocompatibility, and versatility of these unique charged 2D structures abundantly available in nature have enabled the extensive applications of clays in human history. Recent advances in the use of clays in nanostructures and as components of polymer clay nanocomposites have exponentially expanded the use of clays in medicine. This review covers the details of structures and biomedical applications of several common clays, including montmorillonite, LAPONITE®, kaolinite, and halloysite. Here we describe the applications of these clays in wound dressings as hemostatic agents in drug delivery of drugs for cancer and other diseases and tissue engineering. Also reviewed are recent experimental and modeling studies that elucidate the impact of clay structures on cellular processes and cell adhesion processes. Various mechanisms of clay-mediated bioactivity, including protein localization, modulation of cell adhesion, biomineralization, and the potential of clay nanoparticles to impact cell differentiation, are presented. We also review the current developments in understanding the impact of clays on cellular responses. This review also elucidates new emerging areas of use of nanoclays in osteogenesis and the development of in vitro models of bone metastasis of cancer.

Topographical and Compositional Gradient Tubular Scaffold for Bone to Tendon Interface Regeneration

The enthesis is an extremely specific region, localized at the tendon–bone interface (TBI) and made of a hybrid connection of fibrocartilage with minerals. The direct type of enthesis tissue is commonly subjected to full laceration, due to the stiffness gradient between the soft tissues and hard bone, and this often reoccurs after surgical reconstruction. For this purpose, the present work aimed to design and develop a tubular scaffold based on pullulan (PU) and chitosan (CH) and intended to enhance enthesis repair. The scaffold was designed with a topographical gradient of nanofibers, from random to aligned, and hydroxyapatite (HAP) nanoparticles along the tubular length. In particular, one part of the tubular scaffold was characterized by a structure similar to bone hard tissue, with a random mineralized fiber arrangement; while the other part was characterized by aligned fibers, without HAP doping. The tubular shape of the scaffold was also designed to be extemporarily loaded with chondroitin sulfate (CS), a glycosaminoglycan effective in wound healing, before the surgery. Micro CT analysis revealed that the scaffold was characterized by a continuous gradient, without interruptions from one end to the other. The gradient of the fiber arrangement was observed using SEM analysis, and it was still possible to observe the gradient when the scaffold had been hydrated for 6 days. In vitro studies demonstrated that human adipose stem cells (hASC) were able to grow and differentiate onto the scaffold, expressing the typical ECM production for tendon in the aligned zone, or bone tissue in the random mineralized part. CS resulted in a synergistic effect, favoring cell adhesion/proliferation on the scaffold surface. These results suggest that this tubular scaffold loaded with CS could be a powerful tool to support enthesis repair upon surgery.

Two-dimensional nanovermiculite and polycaprolactone electrospun fibers composite scaffolds promoting diabetic wound healing

BACKGROUND

Promoting diabetic wound healing is still a challenge, and angiogenesis is believed to be essential for diabetic wound healing. Vermiculite is a natural clay material that is very easy to obtain and exhibits excellent properties of releasing bioactive ions, buffering pH, adsorption, and heat insulation. However, there are still many unsolved difficulties in obtaining two-dimensional vermiculite and using it in the biomedical field in a suitable form.

RESULTS

In this study, we present a versatile organic-inorganic composite scaffold, which was constructed by embedding two-dimensional vermiculite nanosheets in polycaprolactone electrospun fibers, for enhancing angiogenesis through activation of the HIF-1α signaling pathway and promoting diabetic wound healing both in vitro and in vivo.

CONCLUSIONS

Together, the rational-designed polycaprolactone electrospun fibers-based composite scaffolds integrated with two-dimensional vermiculite nanosheets could significantly improve neo-vascularization, re-epithelialization, and collagen formation in the diabetic wound bed, thus promoting diabetic wound healing. This study provides a new strategy for constructing bioactive materials for highly efficient diabetic wound healing.

Inorganic Nanomaterials in Tissue Engineering

In recent decades, the demand for replacement of damaged or broken tissues has increased; this poses the attention on problems related to low donor availability. For this reason, researchers focused their attention on the field of tissue engineering, which allows the development of scaffolds able to mimic the tissues' extracellular matrix. However, tissue replacement and regeneration are complex since scaffolds need to guarantee an adequate hierarchical structured morphology as well as adequate mechanical, chemical, and physical properties to stand the stresses and enhance the new tissue formation. For this purpose, the use of inorganic materials as fillers for the scaffolds has gained great interest in tissue engineering applications, due to their wide range of physicochemical properties as well as their capability to induce biological responses. However, some issues still need to be faced to improve their efficacy. This review focuses on the description of the most effective inorganic nanomaterials (clays, nano-based nanomaterials, metal oxides, metallic nanoparticles) used in tissue engineering and their properties. Particular attention has been devoted to their combination with scaffolds in a wide range of applications. In particular, skin, orthopaedic, and neural tissue engineering have been considered.

Influence of halloysite nanotubes on the efficiency of Asparaginase against mice Ehrlich solid carcinoma

Herein, the impact of the halloysite nanotubes to suppress the side effects of Asparaginase (ANase) cellular proliferation was investigated. Methods: A total of 100 adult male mice was employed. These mice were divided into four equal groups; Group 1 (control), Group 2 (ESC group) of a single dose of 0.15 ml Ehrlich cells (2 × 106) intraperitoneal infusion(IP), Group 3 (ESC + ANase group) received six doses equal treatments of Intratumoral (IT) 0.07 ml Aspragnase (7 mg/kg) over two weeks. For two weeks, Group 4 (ESC + ASNase + HNTs) received an IT administration of 0.07 ml Asparaginase stocked on Halloysite nanotubes (HNTs) (30 mg/kg) three times per week. A blood specimen was collected, and the liver was removed to be investigated histologically. Results: TEM measurements for the Halloysite nanoclay showed their tubular cylindrical shape with a mean diameter of 50 nm and an average length of 1 μm, whereas The X-ray diffraction pattern of the Halloysite nanoclay showed their characteristic peaks. ESC increases the serum levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and bilirubin than control and other groups, even as albumin and total protein were decreasing. After using Halloysite Nanotube, the rates of these variables were enhanced up to 75%. The hepatocytes histological studies showed protection against Ehrlich Solid carcinoma-induced degenerative, necrotic, and inflammatory changes up to 70%. In conclusion, halloysite nanotubes have demonstrated effective removal of Ehrlich solid carcinoma in mice using an ASNase delivery system. It promoted the ASNase to inhibit the adverse effect of ANase's on the liver and remove the tumour cells.

Maltodextrin-amino acids electrospun scaffolds cross-linked with Maillard-type reaction for skin tissue engineering

The goal of this work is the design and the development of scaffolds based on maltodextrin (MD) to recover chronic lesions. MD was mixed with arginine/lysine/polylysine and the electrospinning was successfully used to prepare scaffolds with uniform and continuous nanofibers having regular shape and smooth surface. A thermal treatment was applied to obtain insoluble scaffolds in aqueous environment, taking the advantage of amino acids-polysaccharide conjugates formed via Maillard-type reaction. The morphological analysis showed that the scaffolds had nanofibrous structures, and that the cross-linking by heating did not significantly change the nanofibers' dimensions and did not alter the system stability. Moreover, the heating process caused a reduction of free amino group and proportionally increased scaffold cross-linking degree. The scaffolds were elastic and resistant to break, and possessed negative zeta potential in physiological fluids. These were characterized by direct antioxidant properties and Fe²⁺ chelation capability (indirect antioxidant properties). Moreover, the scaffolds were cytocompatible towards fibroblasts and monocytes-derived macrophages, and did not show any significant pro-inflammatory activity. Finally, those proved to accelerate the recovery of the burn/excisional wounds. Considering all the features, MD-poly/amino acids scaffolds could be considered as promising medical devices for the treatment of chronic wounds.

Therapeutic Applications of Halloysite

In recent years, nanomaterials have attracted significant research interest for applications in biomedicine. Many kinds of engineered nanomaterials, such as lipid nanoparticles, polymeric nanoparticles, porous nanomaterials, silica, and clay nanoparticles, have been investigated for use in drug delivery systems, regenerative medicine, and scaffolds for tissue engineering. Some of the most attractive nanoparticles for biomedical applications are nanoclays. According to their mineralogical composition, approximately 30 different nanoclays exist, and the more commonly used clays are bentonite, halloysite, kaolinite, laponite, and montmorillonite. For millennia, clay minerals have been extensively investigated for use in antidiarrhea solutions, anti-inflammatory agents, blood purification, reducing infections, and healing of stomach ulcers. This widespread use is due to their high porosity, surface properties, large surface area, excellent biocompatibility, the potential for sustained drug release, thermal and chemical stability. We begin this review by discussing the major nanoclay types and their application in biomedicine, focusing on current research areas for halloysite in biomedicine. Finally, recent trends and future directions in HNT research for biomedical application are explored.

Smart Device for Biologically Enhanced Functional Regeneration of Osteo-Tendon Interface

The spontaneous healing of a tendon laceration results in the formation of scar tissue, which has lower functionality than the original tissue. Moreover, chronic non-healing tendon injuries frequently require surgical treatment. Several types of scaffolds have been developed using the tissue engineering approach, to complement surgical procedures and to enhance the healing process at the injured site. In this work, an electrospun hybrid tubular scaffold was designed to mimic tissue fibrous arrangement and extracellular matrix (ECM) composition, and to be extemporaneously loaded into the inner cavity with human platelet lysate (PL), with the aim of leading to complete post-surgery functional regeneration of the tissue for functional regeneration of the osteo-tendon interface. For this purpose, pullulan (P)/chitosan (CH) based polymer solutions were enriched with hydroxyapatite nanoparticles (HP) and electrospun. The nanofibers were collected vertically along the length of the scaffold to mimic the fascicle direction of the tendon tissue. The scaffold obtained showed tendon-like mechanical performance, depending on HP content and tube size. The PL proteins were able to cross the scaffold wall, and in vitro studies have demonstrated that tenocytes and osteoblasts are able to adhere to and proliferate onto the scaffold in the presence of PL; moreover, they were also able to produce either collagen or sialoproteins, respectively-important components of ECM. These results suggest that HP and PL have a synergic effect, endorsing PL-loaded HP-doped aligned tubular scaffolds as an effective strategy to support new tissue formation in tendon-to-bone interface regeneration.

Benefits and Risks of Clays and Clay Minerals to Human Health From Ancestral to Current Times: A Synoptic Overview

Clay, or more precisely, certain clay typologies, have been used traditionally by humans for therapeutic, nutritional, and skin-care purposes though they may be responsible for some relatively rare but significant health and skin-care risks. For example, clay particles could adsorb and make available for elimination or excretion any potential toxic elements or toxins being ingested or produced, but they could also adsorb and make available for incorporation, through ingestion or through dermal absorption, toxic elements, e.g. heavy metals. Geophagy has been observed in all parts of the world since Antiquity, reflecting cultural practices, religious beliefs, and physiological needs, be they nutritional (dietary supplementation) or as a remedy for disease. Some clays and clay minerals are employed widely in both the pharmaceutical and cosmetics industries as active compounds/agents and as excipients. In the biomedical field, some clay minerals such as halloysite and montmorillonite are known for their effective role as carriers for the control and sustainable delivery of active drug molecules, and in the biomaterials field some clay minerals are used for scaffold, hydrogel, foam, and film production. Constraints, both chemical and microbiological, on the use of clay-based products for therapeutic and cosmetic topical applications are generally imposed by sanitary regulations, and some solutions are proposed herein to control and reduce such restrictions. Particular emphasis is placed here on peloids and pelotherapy, as well as on manipulated and modified peloids, and specifically on tailored peloids or ‘designed and engineered’ peloids, and their derivatives, bactericidal peloids and ointments. As far as the so-called ‘killer clays’ are concerned, their pre-requisites, mechanisms of action, and disinfection role are also enhanced. Podoconiosis is an environment-related or geochemical disease that occurs in tropical highland areas, and is caused by long-term exposure of bare feet to volcanic, red-clay soil and affects some people, particularly those working in agriculture in some regions of Africa, Asia, and South America.

Biomaterials for Soft Tissue Repair and Regeneration: A Focus on Italian Research in the Field

Tissue repair and regeneration is an interdisciplinary field focusing on developing bioactive substitutes aimed at restoring pristine functions of damaged, diseased tissues. Biomaterials, intended as those materials compatible with living tissues after in vivo administration, play a pivotal role in this area and they have been successfully studied and developed for several years. Namely, the researches focus on improving bio-inert biomaterials that well integrate in living tissues with no or minimal tissue response, or bioactive materials that influence biological response, stimulating new tissue re-growth. This review aims to gather and introduce, in the context of Italian scientific community, cutting-edge advancements in biomaterial science applied to tissue repair and regeneration. After introducing tissue repair and regeneration, the review focuses on biodegradable and biocompatible biomaterials such as collagen, polysaccharides, silk proteins, polyesters and their derivatives, characterized by the most promising outputs in biomedical science. Attention is pointed out also to those biomaterials exerting peculiar activities, e.g., antibacterial. The regulatory frame applied to pre-clinical and early clinical studies is also outlined by distinguishing between Advanced Therapy Medicinal Products and Medical Devices.

One-Shot Preparation of Polybasic Ternary Hybrid Cryogels Consisting of Halloysite Nanotubes and Tertiary Amine Functional Groups: An Efficient and Convenient Way by Freezing-Induced Gelation

A convenient method for the preparation of polybasic ternary hybrid cryogels consisting of Halloysite nanotubes (HNTs) and tertiary amine functional groups by freezing-induced gelation is proposed. Ternary hybrid gels were produced via one-shot radical terpolymerization of 2-hydroxyethyl methacrylate (HEMA), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), and DEAEMA in the presence of HNTs. The equilibrium swelling in various swelling media and the mechanical properties of the produced ternary hybrid gels were analyzed to investigate their network structure and determine their final performance. The swelling ratio of HNT-free gels was significantly higher than the ternary hybrid gels composed of high amount of HNTs. The addition of HNTs to terpolymer network did not suppress pH- and temperature-sensitive behavior. While DEAEMA groups were effective for pH-sensitive swelling, it was determined that both HEMA and DEAEMA groups were effective in temperature-sensitive swelling. Ternary hybrid gels simultaneously demonstrated both negative and positive temperature-responsive swelling behavior. The swelling ratio changed considerably according to swelling temperature. Both DEAEMA and HEMA monomers in terpolymer structure were dominant in temperature-sensitive swelling. Mechanical tests in compression of both as-prepared and swollen-state demonstrated that strength and modulus of hybrid cryogels significantly increased with addition of HNTs without significant loss of mechanical strength. Ultimately, the results of the current system can benefit characterization with analysis tools for the application of innovative materials.

Electrospun Scaffolds in Periodontal Wound Healing

Periodontitis is a set of inflammatory conditions affecting the tissues surrounding the teeth predominantly sustained by bacterial infections. The aim of the work was the design and the development of scaffolds based on biopolymers to be inserted in the periodontal pocket to restore tissue integrity and to treat bacterial infections. Nanofibrous scaffolds were prepared by means of electrospinning. Gelatin was considered as base component and was associated to low and high molecular weight chitosans and alginate. The scaffolds were characterized by chemico-physical properties (morphology, solid state-FTIR and differential scanning calorimetry (DSC)-surface zeta potential and contact angle), and mechanical properties. Moreover, preclinical properties (cytocompatibility, fibroblast and osteoblast adhesion and proliferation and antimicrobial properties) were assessed. All the scaffolds were based on cylindrical and smooth nanofibers and preserved their nanofibrous structure upon hydration independently of their composition. They possessed a high degree of hydrophilicity and negative zeta potentials in a physiological environment, suitable surface properties to enhance cell adhesion and proliferation and to inhibit bacteria attachment. The scaffold based on gelatin and low molecular weight chitosan proved to be effective in vitro to support both fibroblasts and osteoblasts adhesion and proliferation and to impair the proliferation of Streptococcus mutans and Aggregatibacter actinomycetemcomitans, both pathogens involved in periodontitis.

Nanotechnology-Based Medical Devices for the Treatment of Chronic Skin Lesions: From Research to the Clinic

Chronic wounds, such as pressure ulcers, diabetic ulcers, venous ulcers and arterial insufficiency ulcers, are lesions that fail to proceed through the normal healing process within a period of 12 weeks. The treatment of skin chronic wounds still represents a great challenge. Wound medical devices (MDs) range from conventional and advanced dressings, up to skin grafts, but none of these are generally recognized as a gold standard. Based on recent developments, this paper reviews nanotechnology-based medical devices intended as skin substitutes. In particular, nanofibrous scaffolds are promising platforms for wound healing, especially due to their similarity to the extracellular matrix (ECM) and their capability to promote cell adhesion and proliferation, and to restore skin integrity, when grafted into the wound site. Nanotechnology-based scaffolds are emphasized here. The discussion will be focused on the definition of critical quality attributes (chemical and physical characterization, stability, particle size, surface properties, release of nanoparticles from MDs, sterility and apyrogenicity), the preclinical evaluation (biocompatibility testing, alternative in vitro tests for irritation and sensitization, wound healing test and animal wound models), the clinical evaluation and the CE (European Conformity) marking of nanotechnology-based MDs.

Wound Healing Activity of Nanoclay/Spring Water Hydrogels

BACKGROUND

hydrogels prepared with natural inorganic excipients and spring waters are commonly used in medical hydrology. Design of these clay-based formulations continues to be a field scarcely addressed. Safety and wound healing properties of different fibrous nanoclay/spring water hydrogels were addressed.

METHODS

in vitro biocompatibility, by means of MTT assay, and wound healing properties were studied. Confocal Laser Scanning Microscopy was used to study the morphology of fibroblasts during the wound healing process.

RESULTS

all the ingredients demonstrated to be biocompatible towards fibroblasts. Particularly, the formulation of nanoclays as hydrogels improved biocompatibility with respect to powder samples at the same concentration. Spring waters and hydrogels were even able to promote in vitro fibroblasts motility and, therefore, accelerate wound healing with respect to the control.

CONCLUSION

fibrous nanoclay/spring water hydrogels proved to be skin-biocompatible and to possess a high potential as wound healing formulations. Moreover, these results open new prospects for these ingredients to be used in new therapeutic or cosmetic formulations.

Norfloxacin-Loaded Electrospun Scaffolds: Montmorillonite Nanocomposite vs. Free Drug

Infections in nonhealing wounds remain one of the major challenges. Recently, nanomedicine approach seems a valid option to overcome the antibiotic resistance mechanisms. The aim of this study was the development of three types of polysaccharide-based scaffolds (chitosan-based (CH), chitosan/chondroitin sulfate-based (CH/CS), chitosan/hyaluronic acid-based (CH/HA)), as dermal substitutes, to be loaded with norfloxacin, intended for the treatment of infected wounds. The scaffolds have been loaded with norfloxacin as a free drug (N scaffolds) or in montmorillonite nanocomposite (H—hybrid-scaffolds). Chitosan/glycosaminoglycan (chondroitin sulfate or hyaluronic acid) scaffolds were prepared by means of electrospinning with a simple, one-step process. The scaffolds were characterized by 500 nm diameter fibers with homogeneous structures when norfloxacin was loaded as a free drug. On the contrary, the presence of nanocomposite caused a certain degree of surface roughness, with fibers having 1000 nm diameters. The presence of norfloxacin–montmorillonite nanocomposite (1%) caused higher deformability (90–120%) and lower elasticity (5–10 mN/cm²), decreasing the mechanical resistance of the systems. All the scaffolds were proven to be degraded via lysozyme (this should ensure scaffold resorption) and this sustained the drug release (from 50% to 100% in 3 days, depending on system composition), especially when the drug was loaded in the scaffolds as a nanocomposite. Moreover, the scaffolds were able to decrease the bioburden at least 100-fold, proving that drug loading in the scaffolds did not impair the antimicrobial activity of norfloxacin. Chondroitin sulfate and montmorillonite in the scaffolds are proven to possess a synergic performance, enhancing the fibroblast proliferation without impairing norfloxacin’s antimicrobial properties. The scaffold based on chondroitin sulfate, containing 1% norfloxacin in the nanocomposite, demonstrated adequate stiffness to sustain fibroblast proliferation and the capability to sustain antimicrobial properties to prevent/treat nonhealing wound infection during the healing process.