Halloysite/Keratin Nanocomposite for Human Hair Photoprotection Coating

Development of alginate film filled with halloysite-carbon dots for active food packaging

The development of functional bionanocomposites for active food packaging is of current interest to replace non-biodegradable plastic coatings. In the present work, we report the synthesis of an alginate-based nanocomposite filled with modified halloysite nanotubes (HNTs) to develop coatings with improved barrier properties for food packaging. Firstly, HNTs were chemically modified by the introduction of carbon dots units (CDs) onto their external surface (HNTs-CDs) obtaining a nanomaterial where CDs are uniformly present onto the tubes as verified by morphological investigations, with good UV absorption and antioxidant properties. Afterwards, these were dispersed in the alginate matrix to obtain the alginate/HNTs-CDs nanocomposite (Alg/HNTs-CDs) whose morphology was imaged by AFM measurements. The UV and water barrier properties (in terms of moisture content and water vapor permeability) were investigated, and the antioxidant properties were evaluated as well. To confer some antimicrobial properties to the final nanocomposite, the synthetized filler was loaded with a natural extract (E) from M. cisplatensis. Finally, the extract kinetic release both from the filler and from the nanocomposite was studied in a medium mimicking a food simulant and preliminary studies on the effect of Alg/HNTs-CDs/E on coated and uncoated fruits, specifically apples and bananas were also carried out.

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.

Thermogravimetric Analysis of Moisture in Natural and Thermally Treated Clay Materials

Clays are a class of porous materials; their surfaces are naturally covered by moisture. Weak thermal treatment may be considered practical to remove the water molecules, changing the surface properties and making the micro- and/or mesoporosities accessible to interact with other molecules. Herein, a modulated thermogravimetric analysis (MTGA) study of the moisture behavior on the structures of five, both fibrous and laminar, clay minerals is reported. The effect of the thermal treatment at 150 °C, which provokes the release of weakly adsorbed water molecules, was also investigated. The activation energies for the removal of the adsorbed water (Ea) were calculated, and they were found to be higher, namely, from 160 to 190 kJ mol-1, for fibrous clay minerals compared to lamellar structures, ranging in this latter case from 80 to 100 kJ mol-1. The thermal treatment enhances the rehydration in Na-montmorillonite, stevensite, and sepiolite structures with a decrease in the energy required to remove it, while Ea increases significantly in palygorskite (from 164 to 273 kJ mol-1). As a proof of concept, the MTGA results are statistically correlated, together with a full characterization of the physico-chemical properties of the five clay minerals, with the adsorption of two molecules, i.e., aflatoxin B1 (AFB1) and β-carotene. Herein, the amount of adsorbed molecules ranges from 12 to 97% for the former and from 22 to 35% for the latter, depending on the particular clay. The Ea was correlated with AFB1 adsorption with a Spearman score of -0.9. When the adsorbed water is forcibly removed, e.g., under vacuum conditions and high temperatures, the structure becomes the most important, decreasing the Spearman score between β-carotene and Ea to -0.6.

Micropatterning of biologically derived surfaces with functional clay nanotubes

Micropatterning of biological surfaces performed via assembly of nano-blocks is an efficient design method for functional materials with complex organic-inorganic architecture. Halloysite clay nanotubes with high aspect ratios and empty lumens have attracted widespread interest for aligned biocompatible composite production. Here, we give our vision of advances in interfacial self-assembly techniques for these natural nanotubes. Highly ordered micropatterns of halloysite, such as coffee rings, regular strips, and concentric circles, can be obtained through high-temperature evaporation-induced self-assembly in a confined space and shear-force brush-induced orientation. Assembly of these clay nanotubes on biological surfaces, including the coating of human or animal hair, wool, and cotton, was generalized with the indication of common features. Halloysite-coated microfibers promise new approaches in cotton and hair dyeing, medical hemostasis, and flame-retardant tissue applications. An interfacial halloysite assembly on oil microdroplets (Pickering emulsion) and its core-shell structure (functionalization with quantum dots) was described in comparison with microfiber nanoclay coatings. In addition to being abundantly available in nature, halloysite is also biosafe, which makes its spontaneous surface micropatterning prospective for high-performance materials, and it is a promising technique with potential for an industrial scale-up.

Hierarchical Composite Scaffold with Deferoxamine Delivery System to Promote Bone Regeneration via Optimizing Angiogenesis

A bone defect refers to the loss of bone tissue caused by trauma or lesion. Bone defects result in high morbidity and deformity rates worldwide. Autologous bone grafting has been widely applied in clinics as the gold standard of treatment; however, it has limitations. Hence, bone tissue engineering has been proposed and developed as a novel therapeutic strategy for treating bone defects. Rapid and effective vascularization is essential for bone regeneration. In this study, a hierarchical composite scaffold with deferoxamine (DFO) delivery system, DFO@GMs-pDA/PCL-HNTs (DGPN), is developed, focusing on vascularized bone regeneration. The hierarchical structure of DGPN imitates the microstructure of natural bone and interacts with the local extracellular matrix, facilitating cell adhesion and proliferation. The addition of 1 wt% of halloysite nanotubes (HNTs) improves the material properties. Hydrophilic and functional groups conferred by polydopamine (pDA) modifications strengthen the scaffold bioactivity. Gelatin microspheres (GMs) protect the pharmacological activity of DFO, achieving local application and sustained release for 7 days. DFO effectively promotes angiogenesis by activating the signaling pathway of hypoxia inducible factor-1 α. In addition, DFO synergizes with HNTs to promote osteogenic differentiation and matrix mineralization. These results indicate that DGPN promotes bone regeneration and accelerates cranial defect healing.

β-Nicotinamide Mononucleotide Promotes Cell Proliferation and Hair Growth by Reducing Oxidative Stress

β-Nicotinamide mononucleotide (NMN) has shown promising effects on intestinal health, and it is extensively applied as an anti-aging and Alzheimer's disease therapeutic, due to its medicinal properties. The effects of NMN on the growth of mouse hair were observed after hair removal. The results indicated that NMN can reverse the state of hair follicle atrophy, hair thinning, and hair sparsity induced by dihydrotestosterone (DHT), compared to that of minoxidil. In addition, the action mechanisms of NMN promoting hair growth in cultured human dermal papilla cells (HDPCs) treated with DHT were investigated in detail. The incubation of HDPCs with DHT led to a decrease in cell viability and the release of inflammatory mediators, including interleukin-6 (IL-6), interleukin-1Beta (IL-1β) and tumor necrosis factor Alpha (TNF-α). It was found that NMN can significantly lower the release of inflammatory factors induced by DHT in HDPCs. HDPCs cells are protected from oxidative stress damage by NMN, which inhibits the NF-κB p65 inflammatory signaling pathway. Moreover, the levels of androgen receptor (AR), dickkopf-1 (DKK-1), and β-catenin in the HDPCs were assessed using PCR, indicating that NMN can significantly enhance the expression of VEGF, reduced IL-6 levels and suppress the expression of AR and DKK-1, and notably increase β-catenin expression in DHT-induced HDPCs.

Recent Progress in Hair Science and Trichology

Hair is important to our appearance as well as to protect our heads. Human hair mainly consists of proteins (80-85%), melanin pigments (0-5%), water (10-13%), and lipids (1-6%). The physicochemical properties of hair have been studied for over 100 years. However, they are not yet thoroughly understood. In this review, recent progress and the latest findings are summarized from the following three perspectives: structural characteristics, delivery and distribution of active ingredients, and hair as a template. The structural characteristics of hair have been mainly investigated by microscopic and/or spectroscopic techniques such as atomic force microscopy integrated with infrared spectroscopy (AFM-IR) and rheological measurements. The distribution of active ingredients has been generally evaluated through techniques such as nanoscale secondary ion mass spectrometry (NanoSIMS). And finally, attempts to explore the potential of hair to be used as a substrate for flexible device fabrication will be introduced.

New Biocide Based on Tributyltin(IV) Ferulate-Loaded Halloysite Nanotubes for Preserving Historical Paper Artworks

Combining biologically active compounds with nanocarriers is an emerging and promising strategy for enhancing the activities of molecules while reducing their levels of toxicity. Green nanomaterials have recently gained momentum in developing protocols for treating and preserving artifacts. In this study, we designed a functional biohybrid material by incorporating tributyltin(IV) ferulate (TBT-F) into halloysite nanotubes (HNTs), generating a new formulation called HNT/TBT-F. The primary objective was to develop a formulation with robust antimicrobial properties and reinforcing features for treating paper with artistic and historical value. To characterize HNT/TBT-F, assess the HNT's loading capacity, and investigate the TBT-F release kinetics from the nanotubes, various analytical techniques, including UV-Vis and infrared spectroscopies, thermogravimetry, and microscopy analysis, were employed. Furthermore, we evaluated the antimicrobial potential of TBT-F and HNT/TBT-F against Kocuria rhizophila, a bacterial strain known for its opportunistic behavior and a cause of artifact biodeterioration. HNT/TBT-F exhibited a significantly stronger bactericidal effect than TBT-F alone against K. rhizophila cells growing planktonically or those forming a biofilm. This enhanced performance could relate to the confinement of TBT-F within the nanotubes, which likely improved its physical-chemical stability and increased the local concentration of TBT-F upon contact with the bacterial cells. Additionally, we evaluated the mechanical properties of a paper treated with HNT/TBT-F, assessing any potential alterations in its color. The findings of this study highlight the favorable attributes of the HNT/TBT-F formulation and its potential for developing protocols aimed at consolidating and preserving culturally significant paper objects.

Bioactive Compound-Loaded Nanocarriers for Hair Growth Promotion: Current Status and Future Perspectives

Hair loss (alopecia) has a multitude of causes, and the problem is still poorly defined. For curing alopecia, therapies are available in both natural and synthetic forms; however, natural remedies are gaining popularity due to the multiple effects of complex phytoconstituents on the scalp with fewer side effects. Evidence-based hair growth promotion by some plants has been reported for both traditional and advanced treatment approaches. Nanoarchitectonics may have the ability to evolve in the field of hair- and scalp-altering products and treatments, giving new qualities to hair that can be an effective protective layer or a technique to recover lost hair. This review will provide insights into several plant and herbal formulations that have been reported for the prevention of hair loss and stimulation of new hair growth. This review also focuses on the molecular mechanisms of hair growth/loss, several isolated phytoconstituents with hair growth-promoting properties, patents, in vivo evaluation of hair growth-promoting activity, and recent nanoarchitectonic technologies that have been explored for hair growth.

Zinc-Intercalated Halloysite Nanotubes as Potential Nanocomposite Fertilizers with Targeted Delivery of Micronutrients

This study reports on the development of nanocomposites utilizing a mineral inhibitor and a micronutrient filler. The objective was to produce a slow release fertilizer, with zinc sulfate as the filler and halloysite nanotubes as the inhibitor. The study seeks to chemically activate the intercalation of zinc into the macro-, meso-, and micropores of the halloysite nanotubes to enhance their performance. As a result, we obtained three nanocomposites in zinc sulfate solution with concentrations of 2%, 20%, and 40%, respectively, which we named Hly-7Å-Zn2, Hly-7Å-Zn20, and Hly-7Å-Zn40. We investigated the encapsulation of zinc sulfate in halloysite nanotubes using X-ray diffraction analysis, transmission electron spectroscopy, infrared spectroscopy (FTIR), and scanning electron microscopy with an energy-dispersive spectrometer. No significant changes were observed in the initial mineral parameters when exposed to a zinc solution with a concentration of 2 mol%. It was proven that zinc was weakly intercalated in the micropore space of the halloysite through the increase in its interlayer distance from 7.2 to 7.4. With an increase in the concentration of the reacted solution, the average diameter of the nanotubes increased from 96 nm to 129 nm, indicating that the macropore space of the nanotubes, also known as the "site", was filled. The activated nanocomposites exhibit a maximum fixed content of adsorbed zinc on the nanotube surface of 1.4 wt%. The TEM images reveal an opaque appearance in the middle section of the nanotubes. S SEM images revealed strong adhesion of halloysite nanotubes to plant tissues. This property guarantees prolonged retention of the fertilizer on the plant surface and its resistance to leaching through irrigation or rainwater. Surface spraying of halloysite nanotubes offers accurate delivery of zinc to plants and prevents soil and groundwater contamination, rendering this fertilizer ecologically sound. The suggested approach of activating halloysite with a zinc solution appears to be a possible route forward, with potential for the production of tailored fertilizers in the days ahead.

Nanoformulations based on collagenases loaded into halloysite/Veegum® clay minerals for potential pharmaceutical applications

The design and development of nanomaterials capable of penetrate cancer cells is fundamental when anticancer therapy is involved. The use of collagenase (Col) is useful since this enzyme can degrade collagen, mainly present in the tumor extracellular matrix. However, its use is often limited since collagenase suffers from inactivation and short half-life. Use of recombinant ultrapure collagenase or carrier systems for their delivery are among the strategies adopted to increase the enzyme stability. Herein, based on the more stability showed by recombinant enzymes and the possibility to use them in anticancer therapy, we propose a novel strategy to further increase their stability by using halloysite nanotubes (HNTs) as carrier. ColG and ColH were supramolecularly loaded onto HNTs and used as fillers for Veegum gels. The systems could be used for potential local administration of collagenases for solid tumor treatment. All techniques adopted for characterization showed that halloysite interacts with collagenases in different ways depending with the Col considered. Furthermore, the hydrogels showed a very slow release of the collagenases within 24 h. Finally, biological assays were performed by studying the digestion of a type-I collagen matrix highlighting that once released the Col still possessed some activity. Thus we developed carrier systems that could further increase the high recombinant collagenases stability, preventing their inactivation in future in vivo applications for potential local tumor treatment.

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.

Keratin/alginate hybrid hydrogels filled with halloysite clay nanotubes for protective treatment of human hair

Keratin/alginate hydrogels filled with halloysite nanotubes (HNTs) have been tested for the protective coating of human hair. Preliminary studies have been conducted on the aqueous colloidal systems and the corresponding hydrogels obtained by using Ca²⁺ ions as crosslinkers. Firstly, we have investigated the colloidal properties of keratin/alginate/HNTs dispersions to explore the specific interactions occurring between the biomacromolecules and the nanotubes. Then, the rheological properties of the hydrogels have been studied highlighting that the keratin/alginate interactions and the subsequent addition of HNTs facilitate the biopolymer crosslinking. Finally, human hair samples have been treated with the hydrogel systems by the dipping procedure. The protection efficiency of the hydrogels has been evaluated by studying the tensile properties of hair fibers exposed to UV irradiation. In conclusion, keratin/alginate hydrogel filled with halloysite represents a promising formulation for hair protective treatments due to the peculiar structural and rheological characteristics.

Free-Radical Photopolymerization for Curing Products for Refinish Coatings Market

Even though there are many photocurable compositions that are cured by cationic photopolymerization mechanisms, UV curing generally consists of the formation of cross-linking covalent bonds between a resin and monomers via a photoinitiated free radical polymerization reaction, obtaining a three-dimensional polymer network. One of its many applications is in the refinish coatings market, where putties, primers and clear coats can be cured faster and more efficiently than with traditional curing. All these products contain the same essential components, which are resin, monomers and photoinitiators, the latter being the source of free radicals. They may also include additives used to achieve a certain consistency, but always taking into account the avoidance of damage to the UV curing—for example, by removing light from the innermost layers. Surface curing also has its challenges since it can be easily inhibited by oxygen, although this can be solved by adding scavengers such as amines or thiols, able to react with the otherwise inactive peroxy radicals and continue the propagation of the polymerization reaction. In this review article, we cover a broad analysis from the organic point of view to the industrial applications of this line of research, with a wide current and future range of uses.

High-Performance Wigs via the Langmuir-Blodgett Deposition of Keratin/Graphene Oxide Nanocomposite

Wigs provide a common service as hair accessories in people's daily life. However, the traditional wigs, regardless of the matrices derived from human hair or synthetic fibers, are faced with limitations such as short service life, dry and brittle texture, and static electricity. In this work, we described a new strategy for surface coating of wigs via the Langmuir-Blodgett (LB) technique using a nanocomposite composed of hair-derived keratin and graphene oxide (Ker/GO). In contrast to the conventionally used immersion method, this strategy achieved a significantly higher surface coverage with a close-packed structure and controlled deposition layers of the coating, thus delivering high performances, including greatly enhanced ultraviolet (UV) resistance, antistatic electricity, heat dissipation, hydroscopicity, and moisturizing ability, and durability against washing, for both the human hair and synthetic-fiber-based wigs.

AFM Characterization of Halloysite Clay Nanocomposites' Superficial Properties: Current State-of-the-Art and Perspectives

Natural halloysite clay nanotubes (HNTs) are versatile inorganic reinforcing materials for creating hybrid composites. Upon doping HNTs with polymers, coating, or loading them with bioactive molecules, the production of novel nanocomposites is possible, having specific features for several applications. To investigate HNTs composites nanostructures, AFM is a very powerful tool since it allows for performing nano-topographic and morpho-mechanical measurements in any environment (air or liquid) without treatment of samples, like electron microscopes require. In this review, we aimed to provide an overview of recent AFM investigations of HNTs and HNT nanocomposites for unveiling hidden characteristics inside them envisaging future perspectives for AFM as a smart device in nanomaterials characterization.

Hyper 100 °C Langmuir-Blodgett (Langmuir-Schaefer) Technique for Organized Ultrathin Film of Polymeric Semiconductors

In this study, we advanced the conventional Langmuir-Blodgett (LB) method to a high-temperature range (above 100 °C) using a newly manufactured LB machine, which is adaptable to a high-boiling-point subphase, as a universally usable apparatus. A sophisticated trough design, with homogeneous heating capability up to approximately 200 °C, together with automatic film compression and Langmuir-Schaefer type film transfer, enabled the fabrication of highly aligned thin films of polymeric semiconductors with uniaxial alignment of polymer backbones, which is desirable for efficient charge transport. Herein, ultrathin films of semicrystalline thiophene-based semiconductors were prepared on ethylene glycol and heated to 80 °C. The analyses of the transferred films with pressure-area isotherms, atomic force microscopy (AFM), polarized optical microscopy (POM), and grazing-incidence wide-angle X-ray scattering (GIWAXS) indicated that the proposed high-temperature LB method allows ideal deposition of high-quality ultrathin films with molecular layer precision at the selected high-temperature conditions. Furthermore, preparing thin-film donor-acceptor-type copolymers in ionic liquids at high temperatures (up to 140 °C) was a challenging task that was successfully demonstrated in this study. Highly ordered thin films of donor-acceptor polymers with a uniaxial backbone orientation were obtained only at 140 °C. The obtained semicrystalline thin films with uniaxially aligned polymer backbones significantly contribute to the two-dimensional overlap of molecular orbitals, which is likely to promote charge transport. The use of the manufactured automatic LB machines is advantageous for better quality films prepared at higher temperatures (even above 100 °C) from various technical viewpoints, including homogeneous heating, constant compression, and automatic film transfer. The novel methodology proposed herein expands the possibilities of the Hyper 100 °C Langmuir-Blodgett technique, which has not been accessible by the conventional LB method with the aqueous subphase.

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.

Probing Diffusive Dynamics of Natural Tubule Nanoclays with Machine Learning

Reproducibility of the experimental results and object of study itself is one of the basic principles in science. But what if the object characterized by technologically important properties is natural and cannot be artificially reproduced one-to-one in the laboratory? The situation becomes even more complicated when we are interested in exploring stochastic properties of a natural system and only a limited set of noisy experimental data is available. In this paper we address these problems by exploring diffusive motion of some natural clays, halloysite and sepiolite, in a liquid environment. By using a combination of dark-field microscopy and machine learning algorithms, a quantitative theoretical characterization of the nanotubes' rotational diffusive dynamics is performed. Scanning the experimental video with the gradient boosting tree method, we can trace time dependence of the diffusion coefficient and probe different regimes of nonequilibrium rotational dynamics that are due to contacts with surfaces and other experimental imperfections. The method we propose is of general nature and can be applied to explore diffusive dynamics of various biological systems in real time.

Bioactive Keratin and Fibroin Nanoparticles: An Overview of Their Preparation Strategies

In recent years, several studies have focused their attention on the preparation of biocompatible and biodegradable nanocarriers of potential interest in the biomedical field, ranging from drug delivery systems to imaging and diagnosis. In this regard, natural biomolecules—such as proteins—represent an attractive alternative to synthetic polymers or inorganic materials, thanks to their numerous advantages, such as biocompatibility, biodegradability, and low immunogenicity. Among the most interesting proteins, keratin extracted from wool and feathers, as well as fibroin extracted from Bombyx mori cocoons, possess all of the abovementioned features required for biomedical applications. In the present review, we therefore aim to give an overview of the most important and efficient methodologies for obtaining drug-loaded keratin and fibroin nanoparticles, and of their potential for biomedical applications.

Advances in nanotechnology-based hair care products applied to hair shaft and hair scalp disorders

OBJECTIVE

Nanotechnology has been intensively applied to the development of novel cosmetic products for hair and scalp care during the last decades. Such a trend is corroborated by the fact that about 19% of the total nanocosmetics registered in the StatNano database are intended for hair and scalp care. Nanotechnology-enabled formulations based on nanoparticles, cyclodextrins, liposomes and nanoemulsions have emerged as novel approaches due to chemical stability and their controlled release. Regarding hair care formulations, nanocarriers can target the hair shaft, hair follicle and scalp. Therefore, they have been used to treat several hair disorders, including dandruff and other hair-damaging conditions.

METHODS

This review addressed the most important nanocarriers applied to hair-related disorders improvement. Furthermore, the application for hair photoprotection and improvement of hair colour duration by nanotechnological formulations is also approached. Besides, we provided an overview of the current scenario of available nano-based commercial hair products and novel patented inventions.

RESULTS

From the patent search, the Patent Cooperation Treaty was pointed as the most important depositing agency while the United States of America has been the most depositing country. On the contrary, according to the StatNano database, Brazil stands out in the hair care worldwide market, and it is also the main producer of hair cosmetics based on nanotechnology.

CONCLUSION

As nano-based products offer several advantages over conventional cosmetics, it is expected that in future, there will be more research on nanocarriers applied to hair disorders, as well as commercial products and patent applications.

Effects of Cosmetic Emulsions on the Surface Properties of Mongolian Hair

In the light of clean beauty and sustainability requirements emerging in the personal care market, the urgent need for the replacement of silicones in hair conditioners-with comparable performance and customer experience-has been highlighted in the industry. In this context, the goal of the present study was to investigate the physical effects of different silicone-free conditioner formulations on Mongolian hair after damage due to bleaching and compare the results to property changes induced by a classical silicone-containing formulation. To that end, the morphology, structure, and composition of strands and individual fibers of this hair type were characterized before and after bleaching by means of optical microscopy, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). It is shown that oxidative bleaching causes significant damage to the native hair surface, leading to local depletion or even large-area removal of the outer hydrophobic lipid layer. This results in enhanced wettability of the bleached hair by water (as confirmed by contact angle measurements) and is accompanied by an undesired loss of hair gloss and softness. Upon treatment with suitable cosmetic emulsions, the natural hydrophobicity of intact Mongolian hair can be partially or fully restored, with silicone-free formulations having effects similar to those of established silicone-containing products. The successive influence of bleaching and conditioning was further monitored using inverse gas chromatography (iGC), a technique that probes changes in surface energetics and polarity over an ensemble of an entire hair strand through interactions with specific molecules at the solid/gas interface. The resulting data mirror the macroscopic behavior of the bleached/conditioned hair and provide a quantitative scale for measuring damage and repair effects. Most notably, the effect of bleaching and subsequent conditioning on the haptic perception of hair strands could also be quantified with the aid of a biomimetic measurement system, which identifies increased friction (both tactile and sliding) as the major cause for the strawy feel of bleached hair and indicates successful relubrication after treatment with suitable conditioner formulations. Finally, the different physical properties determined for native, bleached, and reconditioned Mongolian hair are found to be reflected in application-oriented tests, namely in vitro measurements of wet and dry combing work. Overall, the data collected in this work shed novel light on the surface properties of Mongolian hair and highlight that effective hair conditioning after damage can be achieved without silicones in advanced cosmetic emulsions based on octyldodecyl myristate and glyceryl oleate.

Clays as Vehicles for Drug Photostability

Clay minerals are often used due to their high adsorption capacity, which has sparked interest in their biological applications to stabilize drugs and pharmaceutical products. This research aims to summarize information about the stability of drugs, cosmetics, dermocosmetics, and pharmaceutical compounds incorporated in the structure of different clay minerals. The databases used to search the articles were Web of Science, Scopus, PubMed, and Science Direct. Photostabilization of these compounds is reviewed and its importance demonstrated. For biological applications, the increase in solubility and bioavailability of clay minerals has proven useful for them as drug carriers. While their natural abundance, low toxicity, and accessible cost have contributed to classical applications of clay minerals, a wide range of interesting new applications may be facilitated, mainly through incorporating different organic molecules. The search for new functional materials is promising to challenge research on clay minerals in biological or biotechnological approaches.

Nanomaterials in hair care and treatment

Hair care and treatment has evolved significantly through the years as new formulations are continuously being explored in an attempt to meet the demand in cosmetic and medicinal fields. While standard hair care procedures include hair washing, aimed at hair cleansing and maintenance, as well as hair dyeing and bleaching formulations for hair embellishment, modern hair treatments are mainly focused on circumventing hair loss conditions, strengthening hair follicle properties and treat hair infestations. In this regard, active compounds (ACs) included in hair cosmetic formulations include a vast array of hair cleansing and hair dye molecules, and typical hair treatments include anti-hair loss ACs (e.g. minoxidil and finasteride) and anti-lice ACs (e.g. permethrin). However, several challenges still persist, as conventional AC formulations exhibit sub-optimal performance and some may present toxicity issues, calling for an improved design of formulations regarding both efficacy and safety. More recently, nano-based strategies encompassing nanomaterials have emerged as promising tailored approaches to improve the performance of ACs incorporated into hair cosmetics and treatment formulations. The interest in using these nanomaterials is based on account of their ability to: (1) increase stability, safety and biocompatibility of ACs; (2) maximize hair affinity, contact and retention, acting as versatile biointerfaces; (3) enable the controlled release of ACs in both hair and scalp, serving as prolonged AC reservoirs; besides offering (4) hair follicle targeting features attending to the possibility of surface tunability. This review covers the breakthrough of nanomaterials for hair cosmetics and hair treatment, focusing on organic nanomaterials (polymer-based and lipid-based nanoparticles) and inorganic nanomaterials (nanosheets, nanotubes and inorganic nanoparticles), as well as their applications, highlighting their potential as innovative multifunctional nanomaterials towards maximized hair care and treatment. STATEMENT OF SIGNIFICANCE: This manuscript is focused on reviewing the nanotechnological strategies investigated for hair care and treatment so far. While conventional formulations exhibit sub-optimal performance and some may present toxicity issues, the selection of improved and suitable nanodelivery systems is of utmost relevance to ensure a proper active ingredient release in both hair and scalp, maximize hair affinity, contact and retention, and provide hair follicle targeting features, warranting stability, efficacy and safety. This innovative manuscript highlights the advantages of nanotechnology-based approaches, particularly as tunable and versatile biointerfaces, and their applications as innovative multifunctional nanomaterials towards maximized hair care and treatment.

Halloysite nanotubes as nanoreactors for heterogeneous micellar catalysis

HYPOTHESIS

Electrostatic attractions between the anionic head group of sodium alkylsulphates and the positively charged inner surface of halloysite nanotubes (HNTs) drive to the formation of tubular inorganic micelles, which might be employed as nanoreactors for the confinement of non polar compounds in aqueous media. On this basis, sodium alkylsulphates/halloysite hybrids could be efficient nanocatalysts for organic reactions occurring in water.

EXPERIMENTS

Sodium decylsulphate (NaDeS) and sodium dodecylsulphate (NaDS) were selected for the functionalization of the halloysite cavity. The composition, the structure and the surface charge properties of the hybrid nanotubes were determined. The actual formation of inorganic micelles was explored by studying the microviscosity and polarity characteristics of the surfactant modified nanotubes through fluorescence spectroscopy experiments using DiPyme as probe. The performances of the sodium alkylsulphates/halloysite composites as micellar catalysts for the Belousov-Zhabotinsky (BZ) reaction were investigated.

FINDINGS

The halloysite functionalization with sodium alkylsulphates generated the formation of hydrophobic microdomains with an enhanced microviscosity. Compared to the surfactant conventional micelles, the functionalized nanotubes induced larger enhancements on the rate constant of the BZ reaction. This is the first report on the surfactant/halloysite hybrids showing their efficiencies as reusable nanocatalysts, which are dependent on their peculiar microviscosity and polarity properties.

Nanomechanical Atomic Force Microscopy to Probe Cellular Microplastics Uptake and Distribution

The concerns regarding microplastics and nanoplastics pollution stimulate studies on the uptake and biodistribution of these emerging pollutants in vitro. Atomic force microscopy in nanomechanical PeakForce Tapping mode was used here to visualise the uptake and distribution of polystyrene spherical microplastics in human skin fibroblast. Particles down to 500 nm were imaged in whole fixed cells, the nanomechanical characterization allowed for differentiation between internalized and surface attached plastics. This study opens new avenues in microplastics toxicity research.

Molecular interaction and partitioning in α-keratin using 1H NMR spin-lattice (T1) relaxation times

The interactions between small molecules and keratins are poorly understood. In this paper, a nuclear magnetic resonance method is presented to measure changes in the ¹H T₁ relaxation times of small molecules in human hair keratin to quantify their interaction with the fibre. Two populations of small-molecule compounds were identified with distinct relaxation times, demonstrating the partitioning of the compounds into different keratin environments. The changes in relaxation time for solvent in hair compared with bulk solvent were shown to be related to the molecular weight (MW) and the partition coefficient, LogP, of the solvent investigated. Compounds with low MWs and high hydrophilicities had greater reductions in their T₁ relaxation times and therefore experienced increased interactions with the hair fibre. The relative population sizes were also calculated. This is a significant step towards modelling the behaviour of small molecules in keratinous materials and other large insoluble fibrous proteins.

Cation effects on the properties of halloysite-confined bis(trifluoromethylsulfonyl)imide based ionic liquids

Four types of ionic liquids (ILs) of [X]TFSI ([X]+ is a cation such as 1-butyl-3-methylimidazolium BMIm+, 1-butyl-1-methylpyrrolidinium BMPyrr+, 1-butyl-1-methylpiperidinium BMPip+ and methyltrioctylammonium MOc3Am+ and TFSI- is the bis(trifluoromethylsulfonyl)imide anion) were confined in halloysite nanoclay (Hal) at an excess ionic liquid concentration (IL : Hal ∼55 : 45 wt%) and studied by X-ray diffraction, TG, DSC analysis and FTIR spectroscopy. It was found that the physicochemical properties of ILs trapped by halloysite at maximum loading are similar to those of bulk ILs and change depending on the cation type and size. The cold crystallization temperature (T cc) and melting point (T m) of the crystalline mesophase in confined BMIm+ and BMPyrr+ ionic liquids are higher than in the bulk ones, while in the amorphous BMPyrr+ mesophase, the T cc and T m values decrease by 9.7 and 14.2 °C, respectively. Confined BMPip+ and MOc3Am+ only have the glass transition temperature (T g), which increases by 1.5 and 8.0 °C, respectively, compared to bulk ILs. The onset decomposition temperature (T d) decreases by 106.5, 40.7, 19.0 and 7.7 °C in BMIm+, BMPip+, BMPyrr+ and MOc3Am+, respectively. The changes in the properties are explained by the cation and anion interaction with halloysite, as well as by the transformation of the ionic liquid structure. It is found that in this case the amount of the TFSI- anion trans-conformer increases in the following order: BMIm+ > BMPyrr+ ∼ BMPip+ >> MOc3Am+.

Sequence Does Not Matter: The Biomedical Applications of DNA-Based Coatings and Cores

Biomedical applications of DNA are diverse but are usually associated with specific recognition of target nucleotide sequences or proteins and with gene delivery for therapeutic or biotechnological purposes. However, other aspects of DNA functionalities, like its nontoxicity, biodegradability, polyelectrolyte nature, stability, thermo-responsivity and charge transfer ability that are rather independent of its sequence, have recently become highly appreciated in material science and biomedicine. Whereas the latest achievements in structural DNA nanotechnology associated with DNA sequence recognition and Watson–Crick base pairing between complementary nucleotides are regularly reviewed, the recent uses of DNA as a raw material in biomedicine have not been summarized. This review paper describes the main biomedical applications of DNA that do not involve any synthesis or extraction of oligo- or polynucleotides with specified sequences. These sequence-independent applications currently include some types of drug delivery systems, biocompatible coatings, fire retardant and antimicrobial coatings and biosensors. The reinforcement of DNA properties by DNA complexation with nanoparticles is also described as a field of further research.

Conversion of Organic Dyes into Pigments: Extraction of Flavonoids from Blackberries (Rubus ulmifolius) and Stabilization

The blackberry’s color is composed mainly of natural dyes called anthocyanins. Their color is red–purple, and they can be used as a natural colorant. Anthocyanins are flavonoids, which are products of plants, and their colors range from orange and red to various shades of blue, purple and green, according to pH. In this study, the chemical composition of an extract obtained from blackberries was defined by LC-ESI/LTQOrbitrap/MS in positive and negative ionization mode. Furthermore, we investigated the adsorption process of blackberry extract using several inorganic fillers, such as metakaolin, silica, Lipari pumice, white pozzolan and alumina. The pigments exhibit different colors as a function of their interactions with the fillers. The analysis of the absorption data allowed the estimation of the maximum adsorbing capacity of each individual filler tested. Through thermogravimetric measurements (TGA), the thermal stability and the real adsorption of the organic extract were determined.

Biotechnology of functional proteins and peptides for hair cosmetic formulations

Cosmetics procedures and products combined with environmental insults and daily routines induce irreversible changes in hair. As result of damage, the hair loses some of its properties like strength, elasticity, and smoothness. Recent studies revealed the positive effects of protein-based cosmetics in providing protection to hair. Additionally, these cosmetic products have also shown a great ability to modify hair fibers. We review the effect of protein-based cosmetic formulations on hair properties like color, scent, strength, shape, and volume, highlighting the potential of keratin-based particles and keratin-fusion proteins. In the future, incorporating multifunctional proteins and peptides in the development of alternative hair formulations will result in advanced, sustainable, ecofriendly cosmetic products with a great impact on the cosmetic industry.

Poly (caprolactone)/sodium-alginate-functionalized halloysite clay nanotube nanocomposites: Potent biocompatible materials for wound healing applications

In this study, halloysite nanotubes (HNTs) were subjected to surface functionalization using sodium alginate and incorporated into poly(caprolactone) (PCL) to fabricate nanocomposites for potential wound healing applications. The nanocomposite films were fabricated through the solution casting technique and characterized using various instrumental methods. The films exhibited enhanced thermal and mechanical properties. FE-SEM and AFM analyses confirmed the uniform dispersion of the HNTs and increased roughness of the films, respectively. The swelling properties, in-vitro enzymatic degradation, and anti-inflammatory activity of the films were also analyzed. The MTT assay performed using NIH3T3 cell lines revealed enhanced cell proliferation (126 ± 1.38) of 5 wt% film. Besides, the cell adhesion tests of the films revealed their cytocompatibility. The scratch assay tests conducted for observing the effectiveness of the films for wound closure showed that the 5 wt% film offered a higher rate of fibroblast cell migration (32.24 ± 0.49) than the pristine PCL film. The HRBCMS assay demonstrated the hemocompatibility of these films. The biological test results indicated the delayed enzymatic degradability and haemocompatiblity of nanocomposites with enhanced cell adhesion, cell proliferation, and cell migration capabilities with respect to fibroblast cells. In summary, the synthesized nanocomposite films can be effectively used in wound healing applications after further clinical trials.

Clay Nanotube Immobilization on Animal Hair for Sustained Anti-Lice Protection

Topical administration of drugs is required for the treatment of parasitic diseases and insect infestations; therefore, fabrication of nanoscale drug carriers for effective insecticide topical delivery is needed. Here we report the enhanced immobilization of halloysite tubule nanoclay onto semiaquatic capybaras which have hydrophobic hair surfaces as compared to their close relatives, land-dwelling guinea pigs, and other agricultural livestock. The hair surface of mammals varies in hydrophobicity having a cortex surrounded by cuticles. Spontaneous 1-2 µm thick halloysite hair coverages on the semi-aquatic rodent capybara, non-aquatic rodent guinea pig, and farm goats were compared. The best coating was found for capybara due to the elevated 5 wt% wax content. As a result, we suggest hair pretreatment with diluted wax for enhanced nanoclay adsorption. The formation of a stable goat hair coverage with a 2-3 µm halloysite layer loaded with permethrin insecticide allowed for long-lasting anti-parasitic protection, enduring multiple rain wettings and washings. We expect that our technology will find applications in animal parasitosis protection and may be extended to prolonged human anti-lice treatment.

Chondroitin Sulfate-Based Cryogels for Biomedical Applications

Cryogels attained from natural materials offer exceptional properties in applications such as tissue engineering. Moreover, Halloysite Nanotubes (HNT) at 1:0.5 weight ratio were embedded into CS cryogels to render additional biomedical properties. The hemolysis index of CS cryogel and CS:HNT cryogels was calculated as 0.77 ± 0.41 and 0.81 ± 0.24 and defined as non-hemolytic materials. However, the blood coagulation indices of CS cryogel and CS:HNT cryogels were determined as 76 ± 2% and 68 ± 3%, suggesting a mild blood clotting capability. The maximum% swelling capacity of CS cryogel was measured as 3587 ± 186%, 4014 ± 184%, and 3984 ± 113%, at pH 1.0, pH 7.4 and pH 9.0, respectively, which were reduced to 1961 ± 288%, 2816 ± 192, 2405 ± 73%, respectively, for CS:HNT cryogel. It was found that CS cryogels can hydrolytically be degraded 41 ± 1% (by wt) in 16-day incubation, whereas the CS:HNT cryogels degraded by 30 ± 1 wt %. There is no chelation for HNT and 67.5 ± 1% Cu(II) chelation for linear CS was measured. On the other hand, the CS cryogel and CS:HNT cryogel revealed Cu(II) chelating capabilities of 60.1 ± 12.5%, and 43.2 ± 17.5%, respectively, from 0.1 mg/mL Cu(II) ion stock solution. Additionally, at 0.5 mg/mL CS, CS:HNT, and HNT, the Fe(II) chelation capacity of 99.7 ± 0.6, 86.2 ± 4.7% and only 11.9 ± 4.5% were measured, respectively, while no Fe(II) was chelated by linear CS chelated Fe(II). As the adjustable and controllable swelling properties of cryogels are important parameters in biomedical applications, the swelling properties of CS cryogels, at different solution pHs, e.g., at the solution pHs of 1.0, 7.4 and 9.0, were measured as 3587 ± 186%, 4014 ± 184%, and 3984 ± 113%, respectively, and the maximum selling% values of CS:HNT cryogels were determined as 1961 ± 288%, 2816 ± 192, 2405 ± 73%, respectively, at the same conditions. Alpha glucosidase enzyme interactions were investigated and found that CS-based cryogels can stimulate this enzyme at any CS formulation.

A nanocomposite adsorbent of metallic copper, polypyrrole, halloysite nanotubes and magnetite nanoparticles for the extraction and enrichment of sulfonamides in milk

A composite adsorbent composed of metallic copper (Cu), polypyrrole (PPy), halloysite nanotubes (HNTs) and magnetite nanoparticles (Fe₃O₄) was developed to extract and enrich sulfonamides by dispersive magnetic solid phase extraction. The composite could adsorb sulfonamides via hydrogen bonding and hydrophobic, π-π and π-electron-metal interactions. The extraction conditions were optimized and the developed composite adsorbent was characterized and provided a large surface area that enhanced extraction efficiency for sulfonamides. Coupled with high performance liquid chromatography, the adsorbent was used to quantitatively determine sulfonamides found in milk samples. The response of the developed method exhibited linearity from 5.0 to 150.0 μg kg^-1 for sulfathiazole, and from 2.5 to 100.0 μg kg^-1 for sulfamerazine, sulfamonomethoxine and sulfadimethoxine. Limits of detection were between 2.5 and 5.0 μg kg^-1. Recoveries of sulfonamides in milk samples ranged from 83.0 to 99.2% with RSDs lower than 6%. The developed composite adsorbent showed good reproducibility and reusability.

Theoretical Study of Retinol, Niacinamide and Glycolic Acid with Halloysite Clay Mineral as Active Ingredients for Topical Skin Care Formulations

The adsorption of retinol, niacinamide and glycolic acid active ingredients on the internal surface of halloysite in an aqueous environment was explored at the molecular level by means of calculations based on quantum mechanics and force fields from empirical interatomic potentials. These active ingredients are stably adsorbed on the internal surface of halloysite forming hydrogen bonds between the hydrogen, oxygen and nitrogen atoms with the hydroxyl groups of the inner surface of the halloysite. In addition, electrostatic interaction between these active ingredients with the water molecules was observed. Therefore, the theoretical results indicate that the adsorption of these active principles is favourable in the halloysite nanotube, which allows directing future experimental investigations for the development and design of retinol, niacinamide and glycolic acid with halloysite nanotubes systems, which may be topical formulations for skincare.

Thermodilatometric Study of the Decay of Zeolite-Bearing Building Materials

Six zeolite-bearing rocks, often used as building materials, were analyzed by thermodilatometry, together with a rock not bearing zeolites and a plaster covering a containing wall made of zeolite-bearing dimension stones, up to 250 °C. The main results obtained were the following: (i) the zeolite-bearing rocks exhibited very small, if any, positive variation of ΔL/L_o (%) up to about 100 °C, whereas they more or less shrank in the temperature range 100–250 °C (final values ranging from −0.21 to −0.92%); (ii) the rock not bearing zeolites regularly expanded through the whole temperature range, attaining a final value of 0.19%; (iii) the plaster showed a thermodilatometric behavior strongly affected by its water content. Obtained results were interpreted based on plain thermal expansion, shrinkage by dehydration, cation migration and thermal collapse of the zeolitic structure. The decay of the zeolite-bearing building materials was essentially related to: (i) the large differences recorded in the thermodilatometric behavior of the various rocks and the plaster; (ii) the different minerogenetic processes that resulted in the deposition of the various zeolite-bearing rocks.

Grafting of (3-Chloropropyl)-Trimethoxy Silane on Halloysite Nanotubes Surface

Modified halloysite nanotubes (HNTs-Cl) were synthesized by a coupling reaction with (3-chloropropyl) trimethoxysilane (CPTMS). The incorporation of chloro-silane onto HNTs surface creates HNTs-Cl, which has great chemical activity and is considered a good candidate as an active site that reacts with other active molecules in order to create new materials with great applications in chemical engineering and nanotechnology. The value of this work lies in the fact that improving the degree of grafting of chloro-silane onto the HNT’s surface has been accomplished by incorporation of HNTs with CPTMS under different experimental conditions. Many parameters, such as the dispersing media, the molar ratio of HNTs/CPTMS/H2O, refluxing time, and the type of catalyst were studied. The greatest degree of grafting was accomplished by using toluene as a medium for the grafting process, with a molar ratio of HNTs/CPTMS/H2O of 1:1:3, and a refluxing time of 4 h. The addition of 7.169 mmol of triethylamine (Et3N) and 25.97 mmol of ammonium hydroxide (NH4OH) led to an increase in the degree of grafting of CPTMS onto the HNT’s surface.

Dark-field/hyperspectral microscopy for detecting nanoscale particles in environmental nanotoxicology research

Nanoscale contaminants (including engineered nanoparticles and nanoplastics) pose a significant threat to organisms and environment. Rapid and non-destructive detection and identification of nanosized materials in cells, tissues and organisms is still challenging, although a number of conventional methods exist. These approaches for nanoparticles imaging and characterisation both inside the cytoplasm and on the cell or tissue outer surfaces, such as electron or scanning probe microscopies, are unquestionably potent tools, having excellent resolution and supplemented with chemical analysis capabilities. However, imaging and detection of nanomaterials in situ, in wet unfixed and even live samples, such as living isolated cells, microorganisms, protozoans and miniature invertebrates using electron microscopy is practically impossible, because of the elaborate sample preparation requiring chemical fixation, contrast staining, matrix embedding and exposure into vacuum. Atomic force microscopy, in several cases, can be used for imaging and mechanical analysis of live cells and organisms under ambient conditions, however this technique allows for investigation of surfaces. Therefore, a different approach allowing for imaging and differentiation of nanoscale particles in wet samples is required. Dark-field microscopy as an optical microscopy technique has been popular among researchers, mostly for imaging relatively large specimens. In recent years, the so-called "enhanced dark field" microscopy based on using higher numerical aperture light condensers and variable numerical aperture objectives has emegred, which allows for imaging of nanoscale particles (starting from 5 nm nanospheres) using almost conventional optical microscopy methodology. Hyperspectral imaging can turn a dark-field optical microscope into a powerful chemical characterisation tool. As a result, this technique is becoming popular in environmental nanotoxicology studies. In this Review Article we introduce the reader into the methodology of enhanced dark-field and dark-field-based hyperspectral microscopy, covering the most important advances in this rapidly-expanding area of environmental nanotoxicology.