Preparation and characterization of poly(vinyl pyrrolidone)/cellulose nanofiber/Aloe Vera composites as a biocompatible hydrating facial mask

This study aimed to enhance the properties of polyvinylpyrrolidone (PVP) for use as biocompatible facial masks. To achieve this, nanofibers were developed by blending PVP with cellulose nanofibers (CNFs) and Aloe vera (AV) powder using electrospinning. The results showed that incorporating CNFs and AV into the PVP matrix led to the formation of smooth and uniform nanofibers. In particular, adding 3-6 wt% AV powder in PVP/CNF composites improved fiber diameter distribution and uniformity compared to pure PVP. The PVP/CNF/AV nanofibers exhibited desirable properties for facial mask applications. They displayed 86-93 % porosity, which allowed for efficient moisture absorption capacity of up to 1829 %, and excellent water vapor permeability rate of 3.92 g/m2h. The mechanical properties of the electrospun nanofiber composites were evaluated through tensile testing. The results showed that Young's modulus values decreased progressively with the addition of CNFs and AV powder to the PVP polymer matrix, indicating a plasticizing effect that enhances flexibility. The fracture strain remained similar across all composites, suggesting that CNFs and AV did not significantly weaken the PVP matrix. The tensile strength initially increased with CNF addition but decreased with incremental AV loading. Biocompatibility studies revealed that all nanofibers exhibited excellent fibroblast viability, surpassing 98 %. This indicates that incorporating CNFs and AV did not compromise cell viability, further highlighting the suitability of the PVP/CNF/AV composites for facial mask applications.

Chitosan-based composite films containing eugenol nanoemulsion, ZnO nanoparticles and Aloe vera gel for active food packaging

Biopolymer-based food packaging films are gaining increasing popularity, as consumers' demands for sustainable alternatives and environmental concerns associated with synthetic plastic packaging grow. In this research work, chitosan-based active antimicrobial films reinforced with eugenol nanoemulsion (EuNE), Aloe vera gel, and zinc oxide nanoparticles (ZnONPs) were fabricated and characterized for their solubility, microstructure, optical properties, antimicrobial and antioxidant activities. The rate of release of EuNE from the fabricated films was also evaluated to determine active nature of the films. The EuNE droplet size was about 200 nm, and they were uniformly distributed throughout the film matrices. Incorporation of EuNE in chitosan drastically improved UV-light barrier property of the fabricated composite film by 3 to 6 folds, while maintaining their transparency. The XRD spectra of the fabricated films showed good compatibility between the chitosan and the incorporated active agents. The incorporation of ZnONPs significantly improved their antibacterial properties against foodborne bacteria and tensile strength about 2-folds, whereas incorporation of EuNE and AVG improved DPPH scavenging activities of the chitosan film up to 95 %, respectively.

Aloe vera-loaded natural rubber latex dressing as a potential complementary treatment for psoriasis

Psoriasis is a disease that causes keratinocytes to proliferate ten times faster than normal, resulting in chronic inflammation and immune cell infiltration in the skin. Aloe vera (A. vera) creams have been used topically for treating psoriasis because they contain several antioxidant species; however, they have several limitations. Natural rubber latex (NRL) has been used as occlusive dressings to promote wound healing by stimulating cell proliferation, neoangiogenesis, and extracellular matrix formation. In this work, we developed a new A. vera-releasing NRL dressing by a solvent casting method to load A. vera into NRL. FTIR and rheological analyzes revealed no covalent interactions between A. vera and NRL in the dressing. We observed that 58.8 % of the loaded A. vera, present on the surface and inside the dressing, was released after 4 days. Biocompatibility and hemocompatibility were validated in vitro using human dermal fibroblasts and sheep blood, respectively. We observed that ~70 % of the free antioxidant properties of A. vera were preserved, and the total phenolic content was 2.31-fold higher than NRL alone. In summary, we combined the antipsoriatic properties of A. vera with the healing activity of NRL to generate a novel occlusive dressing that may be indicated for the management and/or treatment of psoriasis symptoms simply and economically.

High-Content Aloe vera Based Hydrogels: Physicochemical and Pharmaceutical Properties

The present research focuses on the physicochemical and pharmacotechnical properties of new hydrogels obtained using allantoin, xanthan gum, salicylic acid and different concentrations of Aloe vera (5, 10, 20% w/v in solution; 38, 56, 71 wt% in dry gels). The thermal behavior of Aloe vera composite hydrogels was studied using DSC and TG/DTG analyses. The chemical structure was investigated using different characterization methods (XRD, FTIR and Raman spectroscopies) and the morphology of the hydrogels was studied SEM and AFM microscopy. Pharmacotechnical evaluation on tensile strength and elongation, moisture content, swelling and spreadability was also completed. Physical evaluation confirmed that the appearance of the prepared Aloe vera based hydrogels was homogeneous and the color varied from pale beige to deep opaque beige with increasing Aloe vera concentration. All other evaluation parameters, e.g., pH, viscosity, spreadability and consistency were found to be adequate in all hydrogel formulations. SEM and AFM images show that the structure of the hydrogels condensed into homogeneous polymeric solids with the addition of Aloe vera, in accordance with the decrease in peak intensities observed via XRD analysis. These results suggest interactions between the hydrogel matrix and Aloe vera as observed via FTIR and TG/DTG and DSC analyses. Considering that Aloe vera content higher than 10% (w/v) did not stimulate further interactions, this formulation (FA-10) can be used for further biomedical applications.

Exploration of Nanosilver Calcium Alginate-Based Multifunctional Polymer Wafers for Wound Healing

Wound care is an integral part of effective recovery. However, its associated financial burden on national health services globally is significant enough to warrant further research and development in this field. In this study, multifunctional polymer wafers were prepared, which provide antibacterial activity, high cell viability, high swelling capacity and a thermally stable medium which can be used to facilitate the delivery of therapeutic agents. The purpose of this polymer wafer is to facilitate wound healing, by creating nanosilver particles within the polymer matrix itself via a one-pot synthesis method. This study compares the use of two synthetic agents in tandem, detailing the effects on the morphology and size of nanosilver particles. Two synthetic methods with varying parameters were tested, with one method using silver nitrate, calcium chloride and sodium alginate, whilst the other included aloe vera gel as an extra component, which serves as another reductant for nanosilver synthesis. Both methods generated thermally stable alginate matrices with high degrees of swelling capacities (400-900%) coupled with interstitially formed nanosilver of varying shapes and sizes. These matrices exhibited controlled nanosilver release rates which were able to elicit antibacterial activity against MRSA, whilst maintaining an average cell viability value of above 90%. Based on the results of this study, the multifunctional polymer wafers that were created set the standard for future polymeric devices for wound healing. These polymer wafers can then be further modified to suit specific types of wounds, thereby allowing this multifunctional polymer wafer to be applied to different wounding scenarios.

Assessing Polysaccharides/Aloe Vera-Based Hydrogels for Tumor Spheroid Formation

In vitro tumor spheroids have proven to be useful 3D tumor culture models for drug testing, and determining the molecular mechanism of tumor progression and cellular interactions. Therefore, there is a continuous search for their industrial scalability and routine preparation. Considering that hydrogels are promising systems that can favor the formation of tumor spheroids, our study aimed to investigate and develop less expensive and easy-to-use amorphous and crosslinked hydrogels, based on natural compounds such as sodium alginate (NaAlg), aloe vera (AV) gel powder, and chitosan (CS) for tumor spheroid formation. The ability of the developed hydrogels to be a potential spheroid-forming system was evaluated using MDA-MB-231 and U87MG cancer cells. Spheroid abilities were influenced by pH, viscosity, and crosslinking of the hydrogel. Addition of either AV or chitosan to sodium alginate increased the viscosity at pH 5, resulting in amorphous hydrogels with a strong gel texture, as shown by rheologic analysis. Only the chitosan-based gel allowed formation of spheroids at pH 5. Among the variants of AV-based amorphous hydrogels tested, only hydrogels at pH 12 and with low viscosity promoted the formation of spheroids. The crosslinked NaAlg/AV, NaAlg/AV/glucose, and NaAlg/CS hydrogel variants favored more efficient spheroid formation. Additional studies would be needed to use AV in other physical forms and other formulations of hydrogels, as the current study is an initiation, in evaluating the potential use of AV gel in tumor spheroid formation systems.

Flexible Threshold-Type Switching Devices with Low Threshold and High Stability Based on Silkworm Hemolymph

In this paper, a floating-gate flexible nonvolatile memory is reported that is composed of natural biological materials, namely, silkworm hemolymph, graphene quantum dots as the floating-gate layer, and polymethyl methacrylate (PMMA) as the insulating layer. The device has a high ON/OFF current ratio (4.76 × 106), a low setting voltage (<−1.75 V), and good durability and retention ability. The device has two storage characteristics, namely, Flash and WORM, which can be effectively and accurately controlled by adjusting the limiting current during device setting. The resistance switching characteristics are the result of the formation and fracture of conductive filaments. The floating-gate flexible bioresistive random access memory prepared in this paper provides a new idea for the development of multifunctional and biocompatible flexible memory.

Novel Physically Cross-Linked Curcumin-Loaded PVA/Aloe vera Hydrogel Membranes for Acceleration of Topical Wound Healing: In Vitro and In Vivo Experiments

This study aims to prepare novel cross-linked antimicrobial membranes composed of PVA-Aloe vera hydrogels using novel physically cross-linked method via transforming PVA to high crystalline structure using propanol. Curcumin was incorporated to improve the membrane biological properties; while gentamycin improved sharply antimicrobial properties. PVA-Aloe vera hydrogel membranes were analyzed by FTIR, SEM, XRD and TGA measurements for characterizing resultant cross-linked membranes. Physicochemical measurements, e.g., swelling and mechanical stability were assessed for further studying the dressings. Antibacterial activity of cross-linked PVA-Aloe vera-curcumin membranes was tested using five bacterial strains. Results showed that high Aloe vera content in cross-linked membranes has insignificant impact on the release of gentamicin. Adult Wister Albino rats were used to test membrane’s ability for improving the wound healing rate in vivo. In vivo findings showed that PVA/Aloe vera/curcumin membranes dramatically reduced the size of mouse full-thickness wounds, as indicated by a decrease in the wound size. Furthermore, histological tests of wounds dressed with membranes revealed a significant re-epithelialization; compared to wounds treated with cotton gauze and PVA/Aloe vera dressings without curcumin, showing curcumin’s efficacy. These results refer to PVA-Aloe vera-curcumin membrane has exceptional wound healing and skin regeneration capacity.

Temperature and pH Stability of Anthraquinones from Native Aloe vera Gel, Spray-Dried and Freeze-Dried Aloe vera Powders during Storage

The present study explored the stability of extracted anthraquinones (aloin, aloe-emodin and rhein) from whole-leaf Aloe vera gel (WLAG), its freeze-dried powder (FDP) and spray-dried powder (SDP) under varying pH and temperature conditions during storage. Each anthraquinone behaved differently under different processing parameters. The amount of anthraquinones present in the gel was higher than in FDP and SDP. The aloin contents decreased by more than 50% at 50 °C and 70 °C, while at 25 °C and 4 °C, the decrease was moderate. A substantial reduction in aloin concentration was noticed at pH 6.7, whereas it remained unaffected at pH 3.5. The temperature and pH had no significant effect on the stability of aloe-emodin. Interestingly, a small quantity of rhein was detected during storage due to the oxidative degradation of aloin into aloe-emodin and rhein. These findings can provide significant insight into retaining anthraquinones during processing while developing functional foods and nutraceuticals to obtain maximum health benefits.

A sunscreen nanoparticles polymer based on prolonged period of protection

UV rays are one of the most dangerous factors that harm the skin. There is continuous improvement in getting an effective sunscreen that protects the skin from excessive exposure to UV rays. Typically, phenylbenzimidazole-5-sulfonic acid (PBSA) is used as a sun blocking agent, but its disadvantage is that it can photodegrade and cause cell damage. In our work, PBSA was encapsulated in niosomes nanoparticles then coated with chitosan-aloe vera (CS-nio-aloe/PBSA) to form a carrier polymer with novel and potent properties. This polymer controls PBSA release and epidermal penetration. Characterization of CS-nio-aloe/PBSA polymer nanoparticles through transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS). The carrier polymer release rate was studied in vitro and epidermal permeability to coated PBSA was assessed using mouse skin. The nanoparticle polymer containing sunscreen was effectively prepared with an encapsulation efficiency of 80%. The formulation (CS-nio-aloe/PBSA) was completely deposited on the surface of the skin. This supports its use to protect the skin, and its nanostructures stimulate the release of PBSA for a longer period. Encapsulation of PBSA in CS-nio-aloe nanoparticles could allow for further cellular preservation, UV protection, control of free PBSA, and limited penetration through the mouse skin epidermis.

Tunable biological nonvolatile multilevel data storage devices

The speed with which electronic products are updated is continuously increasing. Consequently, since waste electronic products can cause serious environmental pollution, the demand for electronic products made of biological materials is becoming increasingly urgent. Although biological memristors have significant advantages, their electrical characteristics still do not meet the requirements to be used in future nonvolatile memories. Therefore, how to control their electrical characteristics has become a popular topic of research. In this study, tunable biomemristors with an Al/tussah blood (TB)-carbon nanotube (CNT)/indium tin oxide (ITO)/glass structure were fabricated. Such a device exhibits stable bipolar resistance switching behavior and good retention characteristics (10⁴ s). Experimental results show that the ON/OFF current ratio can be effectively controlled by modifying the CNT concentration in the TB-CNT composite film. Multilevel (8 levels, 3 bits per cell) storage capabilities can be achieved in the device by controlling its compliance current in order to achieve high-density storage. The resistance switching behavior originates from the formation and rupture of conductive oxygen vacancy filaments. TB is a promising natural biomaterial in the field of green electronics, and this research could blaze a new trail for the development of biological memory devices. Biomemristors with multilevel resistance states can be used as electronic synapses and are one of the choices for simulating biological synapses.

Aloe Vera extract-based composite nanofibers for wound dressing applications

Natural, biocompatible, and biodegradable composite nanofibers made of Aloe vera extract, pullulan, chitosan, and citric acid were successfully produced via Forcespinning® technology. The addition of Aloe vera extract at different weight percent loadings was investigated. The morphology, thermal properties, physical properties, and water absorption of the nanofibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The developed nanofiber membranes exhibited good water absorption capabilities, synergistic antibacterial activity against Escherichia coli, and promoted cell attachment and growth. Its porous and high surface area structure make it a potential candidate for wound dressing applications due to its ability to absorb excessive blood and exudates, as well as provide protection from infection while maintaining good thermal stability.

Aloe Vera-Mediated Te Nanostructures: Highly Potent Antibacterial Agents and Moderated Anticancer Effects

Cancer and antimicrobial resistance to antibiotics are two of the most worrying healthcare concerns that humanity is facing nowadays. Some of the most promising solutions for these healthcare problems may come from nanomedicine. While the traditional synthesis of nanomaterials is often accompanied by drawbacks such as high cost or the production of toxic by-products, green nanotechnology has been presented as a suitable solution to overcome such challenges. In this work, an approach for the synthesis of tellurium (Te) nanostructures in aqueous media has been developed using aloe vera (AV) extracts as a unique reducing and capping agent. Te-based nanoparticles (AV-TeNPs), with sizes between 20 and 60 nm, were characterized in terms of physicochemical properties and tested for potential biomedical applications. A significant decay in bacterial growth after 24 h was achieved for both Methicillin-resistant Staphylococcus aureus and multidrug-resistant Escherichia coli at a relative low concentration of 5 µg/mL, while there was no cytotoxicity towards human dermal fibroblasts after 3 days of treatment. AV-TeNPs also showed anticancer properties up to 72 h within a range of concentrations between 5 and 100 µg/mL. Consequently, here, we present a novel and green approach to produce Te-based nanostructures with potential biomedical applications, especially for antibacterial and anticancer applications.

Lanthanides-Substituted Hydroxyapatite/Aloe vera Composite Coated Titanium Plate for Bone Tissue Regeneration

PURPOSE

To develop the surface-treated metal implant with highly encouraged positive properties, including high anti-corrosiveness, bio-activeness and bio-compatibleness for orthopedic applications.

METHODS

In this work, the surface of commercially pure titanium (Ti) metal was treated with bio-compatible polydopamine (PD) by merely immersing the Ti plate in PD solution. The composite of trivalent lanthanide minerals (La3+, Ce3+ and Gd3+)-substituted hydroxyapatite (MHAP) with Aloe vera (AV) gel was prepared and coated on the PD-Ti plate by electrophoretic deposition (EPD) method. The choice of trivalent lanthanide ions is based on their bio-compatible nature and bone-seeking properties. The formation of the PD layer, composites, and composite coatings on Ti plate and PD-Ti surface was confirmed by FT-IR, XRD, SEM and HR-TEM observations. In-vitro assessments such as osteoblasts like MG-63 cell viability, alkaline phosphatase activity and mineralization ability of the MHAP/AV composite were tested, and the composite-coated plate was implanted into a rat bone defect model for in-vivo bone regeneration studies.

RESULTS

The coating ability of the MHAP/AV composite was highly preferred to PD-treated Ti plate than an untreated Ti plate due to the metal absorption ability of PD. This was confirmed by SEM analysis. The in-vitro and in-vivo studies show the better osteogenic ability of MHAP/AV composite at 14th day and 4th week of an experimental period, respectively.

CONCLUSION

The osteoblast ability of the fabricated device without producing any adverse effect in the rat model recommends that the fabricated device would serve as a better platform on the hard tissue regeneration for load-bearing applications of orthopedics.

Physicochemical Investigations of Chitosan-Based Hydrogels Containing Aloe Vera Designed for Biomedical Use

In this work, synthesis and investigations on chitosan-based hydrogels modified with Aloe vera juice are presented. These materials were synthesized by UV radiation. Investigations involved analysis of chemical structure by FTIR spectroscopy, sorption properties in physiological liquids, strength properties by texture analyzer, surface topography by Atomic Force Microscopy (AFM technique), and in vitro cytotoxicity by MTT test using L929 murine fibroblasts. Particular attention was focused both on determining the impact of the amount and the molecular weight of the crosslinker used for the synthesis as well as on the introduced additive on the properties of hydrogels. It was proven that modified hydrogels exhibited higher swelling ability. Introduced additive affected the tensile strength of hydrogels—modified materials showed 23% higher elongation. The greater amount of the crosslinker used in the synthesis, the more compact the structure, leading to the lower elasticity and lower sorption of hydrogels was reported. Above 95%, murine fibroblasts remained viable after 24 h incubation with hydrogels. It indicates that tested materials did not exhibit cytotoxicity toward these lines. Additionally, materials with Aloe vera juice were characterized by lower surface roughness. Conducted investigations allowed us to state that such modified hydrogels may be considered as useful for biomedical purposes.

Nature-derived materials for the fabrication of functional biodevices

Nature provides an incredible source of inspiration, structural concepts, and materials toward applications to improve the lives of people around the world, while preserving ecosystems, and addressing environmental sustainability. In particular, materials derived from animal and plant sources can provide low-cost, renewable building blocks for such applications. Nature-derived materials are of interest for their properties of biodegradability, bioconformability, biorecognition, self-repair, and stimuli response. While long used in tissue engineering and regenerative medicine, their use in functional devices such as (bio)electronics, sensors, and optical systems for healthcare and biomonitoring is finding increasing attention. The objective of this review is to cover the varied nature derived and sourced materials currently used in active biodevices and components that possess electrical or electronic behavior. We discuss materials ranging from proteins and polypeptides such as silk and collagen, polysaccharides including chitin and cellulose, to seaweed derived biomaterials, and DNA. These materials may be used as passive substrates or support architectures and often, as the functional elements either by themselves or as biocomposites. We further discuss natural pigments such as melanin and indigo that serve as active elements in devices. Increasingly, combinations of different biomaterials are being used to address the challenges of fabrication and performance in human monitoring or medicine. Finally, this review gives perspectives on the sourcing, processing, degradation, and biocompatibility of these materials. This rapidly growing multidisciplinary area of research will be advanced by a systematic understanding of nature-inspired materials and design concepts in (bio)electronic devices.

Effects of Aloe Vera Gel Extract in Doped Hydroxyapatite-Coated Titanium Implants on in Vivo and in Vitro Biological Properties

Hydroxyapatite-coated titanium alloys have been a popular choice as bone implants for load-bearing applications for the compositional similarity of hydroxyapatite to natural bone. The limited osteoinductive properties exhibited by the hydroxyapatite (HA) coatings have led to the incorporation of growth factor or dopants for improved osseointegration. This study aims to investigate the effects of a naturally occurring aloe vera gel extract, acemannan, in doped hydroxyapatite coatings on the in vitro osteoblast cell viability and in vivo new bone formation in a rat distal femur model. Silver oxide and silica-doped hydroxyapatite coatings were developed by the induction plasma spray coating method on Ti alloys to introduce antibacterial properties along with induction of angiogenic properties, respectively. The doped coating was further consecutively dip coated with acemannan to analyze its effects on the in vivo early stage osseointegration and chitosan to control the burst release of the acemannan from the calcium phosphate matrix. The results show controlled release of acemannan from the chitosan coatings, with enhanced osteoblast cell viability by the incorporation of acemannan in vitro. Improved osseointegration with a seamless implant interface and improved new bone formation was noted by the acemannan and chitosan coating in vivo, 5 weeks after implantation. Our results demonstrate the efficacy of a combination of natural medicine and naturally occurring polymer in a doped hydroxyapatite-coated titanium implant on the bone tissue regeneration for load-bearing orthopedic applications.

Extraction, Purification, Structural Characteristics, Biological Activities and Pharmacological Applications of Acemannan, a Polysaccharide from Aloe vera: A Review

Aloe vera is a medicinal plant species of the genus Aloe with a long history of usage around the world. Acemannan, considered one of the main bioactive polysaccharides of Aloe vera, possesses immunoregulation, anti-cancer, anti-oxidation, wound healing and bone proliferation promotion, neuroprotection, and intestinal health promotion activities, among others. In this review, recent advancements in the extraction, purification, structural characteristics and biological activities of acemannan from Aloe vera were summarized. Among these advancements, the structural characteristics of purified polysaccharides were reviewed in detail. Meanwhile, the biological activities of acemannan from Aloe vera determined by in vivo, in vitro and clinical experiments are summarized, and possible mechanisms of these bioactivities were discussed. Moreover, the latest research progress on the use of acemannan in dentistry and wound healing was also summarized in details. The structure-activity relationships of acemannan and its medical applications were discussed. Finally, new perspectives for future research work on acemannan were proposed. In conclusion, this review summarizes the extraction, purification, structural characteristics, biological activities and pharmacological applications of acemannan, and provides information for the industrial production and possible applications in dentistry and wound healing in the future.

pH-Modulated memristive behavior based on an edible garlic-constructed bio-electronic device

A new type of memristive memory device with an edible garlic-constructed Ag/garlic/fluorine-doped SnO₂(FTO) structure for analog neuromorphic sensor applications was designed.

From dead leaves to sustainable organic resistive switching memory

An environmental-friendly, sustainable, pollution-free, biodegradable, flexible and wearable electronic device hold advanced potential applications. Here, an organic resistive switching memory device with Ag/Leaves/Ti/PET structure on a flexible polyethylene terephthalate (PET) substrate was fabricated for the first time. We observed an obvious resistive switching memory characteristic with large switching resistance ratio and stable cycle performance at room temperature. This work demonstrates that leaves, a useless waste, can be properly treated to make useful devices. Furthermore, the as-fabricated devices can be degraded naturally without damage to the environment.

Artificial Synapses with Short- and Long-Term Memory for Spiking Neural Networks Based on Renewable Materials

Emulation of biological synapses that perform memory and learning functions is an essential step toward realization of bioinspired neuromorphic systems. Artificial synaptic devices have been developed based mostly on inorganic materials and conventional semiconductor device fabrication processes. Here, we propose flexible biomemristor devices based on lignin by a simple solution process. Lignin is one of the most abundant organic polymers on Earth and is biocompatible, biodegradable, as well as environmentally benign. This memristor emulates several essential synaptic behaviors, including analog memory switching, short-term plasticity, long-term plasticity, spike-rate-dependent plasticity, and short-term to long-term transition. A flexible lignin-based artificial synapse device can be operated without noticeable degradation under mechanical bending test. These results suggest lignin can be a promising key component for artificial synapses and flexible electronic devices.

Nanoencapsulation of Aloe vera in Synthetic and Naturally Occurring Polymers by Electrohydrodynamic Processing of Interest in Food Technology and Bioactive Packaging

This work originally reports on the use of electrohydrodynamic processing (EHDP) to encapsulate Aloe vera (AV, Aloe barbadensis Miller) using both synthetic polymers, i.e., polyvinylpyrrolidone (PVP) and poly(vinyl alcohol) (PVOH), and naturally occurring polymers, i.e., barley starch (BS), whey protein concentrate (WPC), and maltodextrin. The AV leaf juice was used as the water-based solvent for EHDP, and the resultant biopolymer solution properties were evaluated to determine their effect on the process. Morphological analysis revealed that, at the optimal processing conditions, synthetic polymers mainly produced fiber-like structures, while naturally occurring polymers generated capsules. Average sizes ranged from 100 nm to above 3 μm. As a result of their different and optimal morphology and, hence, higher AV content, PVP, in the form of nanofibers, and WPC, of nanocapsules, were further selected to study the AV stability against ultraviolet (UV) light exposure. Fourier transform infrared (FTIR) spectroscopy confirmed the successful encapsulation of AV in the biopolymer matrices, presenting both encapsulants a high chemical interaction with the bioactive components. Ultraviolet-visible (UV-vis) spectroscopy showed that, while PVP nanofibers offered a poor effect on the AV degradation during UV light exposure (∼10% of stability after 5 h), WPC nanobeads delivered excellent protection (stability of >95% after 6 h). This was ascribed to positive interactions between WPC and the hydrophilic components of AV and the inherent UV-blocking and oxygen barrier properties provided by the protein. Therefore, electrospraying of food hydrocolloids interestingly appears as a novel potential nanotechnology tool toward the formulation of more stable functional foods and nutraceuticals.

Flexible Multistate Data Storage Devices Fabricated Using Natural Lignin at Room Temperature

The growing interest in bioinspired and sustainable electronics has induced research on biocompatible and biodegradable materials. However, conventional electronic devices have been restricted due to their nonbiodegradable and sometimes harmful and toxic materials, which can even cause environmental issues. Here, we report a resistive switching random access memory (ReRAM) device based on lignin, which is a biodegradable waste product of the paper industry. The active layer of the device can be easily formed using a simple solution process on a plastic substrate. The memory devices show stable bipolar resistive switching behavior with good endurance and retention. Appropriate control of the maximum reset voltage and compliance current can yield multibit data storage capability with at least four resistance states, which can be exploited to realize a high-density memory device. The resistive switching mechanism may be a result of formation and rupture of carbon-rich filaments. These results suggest that lignin is a promising candidate material for an inexpensive and environmentally benign ReRAM device. We believe that this study can initiate a new route toward development of biocompatible and flexible electronics.

New Biofunctional Loading of Natural Antimicrobial Agent in Biodegradable Polymeric Films for Biomedical Applications

The study focuses on the development of novel Aloe vera based polymeric composite films and antimicrobial suture coatings. Polyvinyl alcohol (PVA), a synthetic biocompatible and biodegradable polymer, was combined with Aloe vera, a natural herb used for soothing burning effects and cosmetic purposes. The properties of these two materials were combined together to get additional benefits such as wound healing and prevention of surgical site infections. PVA and Aloe vera were mixed in a fixed quantity to produce polymer based films. The films were screened for antibacterial and antifungal activity against bacterial (E. coli, P. aeruginosa) and fungal strains (Aspergillus flavus and Aspergillus tubingensis) screened. Aloe vera based PVA films showed antimicrobial activity against all the strains; the lowest Aloe vera concentration (5%) showed the highest activity against all the strains. In vitro degradation and release profile of these films was also evaluated. The coating for sutures was prepared, in vitro antibacterial tests of these coated sutures were carried out, and later on in vivo studies of these coated sutures were also performed. The results showed that sutures coated with Aloe vera/PVA coating solution have antibacterial effects and thus have the potential to be used in the prevention of surgical site infections and Aloe vera/PVA based films have the potential to be used for wound healing purposes.

Green synthesized cerium oxide nanoparticle: A prospective drug against oxidative harm

Cerium oxide nanoparticle (CeONP) of size 2-3nm was synthesized by a new, simple and green method at ambient temperature, using cerium nitrate as prime precursor and Aloe vera leaf extract as stabilizing agent. Of the two oxidation states (+3) and (+4) of cerium, it was dominantly present in (+3) state in CeONP and cyclic conversion of Ce(III)O→Ce(IV)O→Ce(III)O by reaction with H2O2 implied uninterrupted antioxidant property of CeONP. Moreover, the higher oxygen defect in the crystal lattice produced particles with higher antioxidant activity. CeONP was found to neutralize the deleterious effects of H2O2 viz., cell death, generation of intracellular reactive oxygen species and loss of connectivity in mouse neural cells. Therefore, CeONP might have potential use in future as an anti-oxidant drug.