Biogenic Vaterite Calcium Carbonate-Silver/Poly(Vinyl Alcohol) Film for Wound Dressing

Vaterite, a spherical polymorph of CaCO3, shows potential as a carrier for the stable and controlled release of silver nanoparticles (AgNPs), preventing their aggregation or loss of efficacy during application. Furthermore, the embedding of CaCO3-Ag in a poly(vinyl alcohol) (PVA) matrix helps effectively encapsulate and protect the CaCO3-Ag microspheres and provides mechanical stability for better contact with the wound surface. This article focuses on the fabrication of an antimicrobial and biocompatible absorbent film embedded with precipitated biogenic vaterite CaCO3-Ag microspheres. The impact of vaterite CaCO3-Ag on the physical, chemical, nanomechanical, biocompatibility, and antimicrobial properties of the PVA films was investigated. The morphology study revealed a bilayer film structure with an inactive and active surface containing homogeneously distributed vaterite CaCO3-Ag. The X-ray photoelectron spectroscopy (XPS) analysis of the spin-orbit splitting in the Ag 3d5/2 and Ag 3d3/2 peaks indicated the presence of both metallic and ionic states of silver in vaterite CaCO3-Ag prior to its incorporation into the PVA polymer matrix. However, upon embedding in the PVA matrix, a subsequent transformation to solely ionic states was observed. The nanomechanical properties of PVA improved, and the reduced modulus and hardness increased to 14.62 ± 5.23 and 0.64 ± 0.29 GPa, respectively. The films demonstrate a significant activity toward Gram-negative Escherichia coli bacteria. The release of AgNPs was studied in both open and closed systems at pH 6, mimicking the pH environment of the wound, and it demonstrated a dependency on the type of capping agent used for synthesis and loading of AgNPs. The results further revealed the biocompatibility of the prepared films with human dermal fibroblast cells at a concentration of ≤5 mg/mL, making them applicable and functional for wound dressing applications.

Membranes for the life sciences and their future roles in medicine

Since the global outbreak of COVID-19, membrane technology for clinical treatments, including extracorporeal membrane oxygenation (ECMO) and protective masks and clothing, has attracted intense research attention for its irreplaceable abilities. Membrane research and applications are now playing an increasingly important role in various fields of life science. In addition to intrinsic properties such as size sieving, dissolution and diffusion, membranes are often endowed with additional functions as cell scaffolds, catalysts or sensors to satisfy the specific requirements of different clinical applications. In this review, we will introduce and discuss state-of-the-art membranes and their respective functions in four typical areas of life science: artificial organs, tissue engineering, in vitro blood diagnosis and medical support. Emphasis will be given to the description of certain specific functions required of membranes in each field to provide guidance for the selection and fabrication of the membrane material. The advantages and disadvantages of these membranes have been compared to indicate further development directions for different clinical applications. Finally, we propose challenges and outlooks for future development.

Environmental remediation using metals and inorganic and organic materials: a review

In recent times, environmental pollution has been an alarming concern. This is increasing day-in-and-day-out, especially in the Asia-Pacific region due to the increasing population, urbanization, industrialization and inappropriate waste management measures. Pollution abatement is the need of the hour to sustain the biosphere in general and the human life in particular. A range of physical, chemical and biological strategies are commonly employed to remove pollutants from the contained water, soil and air. Physical, chemical or physicochemical remediation processes are commonly employed owing to their high efficiency, stability, recyclable property and low procurement cost as compared to metals, inorganic and organic materials. Materials of the later type include biocomposites, thin films, modified (bio)polymers, nanoparticles, nanofilters, sorbent like activated charcoal, and carbon nanotubes and nanosensors. Remediation mechanism largely follows sorption, degradation, oxidation, reduction, catalytic conversion, detection and microbial toxicity principles. This review details the mechanisms of action by these various remediating entities, their successful applications in pollution abatement, drawbacks and future prospects.HighlightsEnvironmental remediation using metals, inorganic and organic materials are discussed extensively.Major remediating approaches, viz., physical, physicochemical and chemical are elaborated citing latest references.The significance of biocomposites, biopolymers, polymers, thin films, nanoparticles, nanofilters, nanosensors and sorbents in remediation are highlighted.Pollutant removal from water, air and soil has been precisely discussed.A note on drawbacks, improvement and future prospects of remediating agents is presented.

Role of Nanoparticles in Environmental Remediation: An Insight into Heavy Metal Pollution from Dentistry

Environmental damage is without a doubt one of the most serious issues confronting society today. As dental professionals, we must recognize that some of the procedures and techniques we have been using may pose environmental risks. The usage and discharge of heavy metals from dental set-ups pollute the environment and pose a serious threat to the ecosystem. Due to the exclusive properties of nanosized particles, nanotechnology is a booming field that is being extensively studied for the remediation of pollutants. Given that the nanoparticles have a high surface area to volume ratio and significantly greater reactivity, they have been greatly considered for environmental remediation. This review aims at identifying the heavy metal sources and their environmental impact in dentistry and provides insights into the usage of nanoparticles in environmental remediation. Although the literature on various functions of inorganic nanoparticles in environmental remediation was reviewed, the research is still confined to laboratory set-ups and there is a need for more studies on the usage of nanoparticles in environmental remediation.

Poly(lactic acid)/Zinc/Alginate Complex Material: Preparation and Antimicrobial Properties

The aim of this study was to investigate an antimicrobial and degradable composite material consisting of melt-blown poly(lactic acid) nonwoven fabrics, alginate, and zinc. This paper describes the method of preparation and the characterization of the physicochemical and antimicrobial properties of the new fibrous composite material. The procedure consists of fabrication of nonwoven fabric and two steps of dip-coating modification: (1) impregnation of nonwoven samples in the solution of alginic sodium salt and (2) immersion in a solution of zinc (II) chloride. The characterization and analysis of new material included scanning electron microscopy (SEM), specific surface area (SSA), and total/average pore volume (BET). The polylactide/alginate/Zn fibrous composite were subjected to microbial activity tests against colonies of Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli) bacterial strains, and the following fungal strains: Aspergillus niger van Tieghem and Chaetomium globosum. These results lay a technical foundation for the development and potential application of new composite as an antibacterial/antifungal material in biomedical areas.

Mitigation of environmentally-related hazardous pollutants from water matrices using nanostructured materials - A review

An unprecedented rise in population growth and rapid worldwide industrial development are associated with the increasing discharge of a range of toxic and baleful compounds. These toxic pollutants including dyes, endocrine-disrupters, heavy metals, personal care products, and pharmaceuticals are destructing nature's balance and intensifying environmental toxicity at a disquieting rate. Therefore, finding better, novel and more environmentally sound approaches for wastewater remediation are of great importance. Nanoscale materials have opened up some new horizons in various fields of science and technology. Among a range of treatment technologies, nanostructured materials have recently received incredible interest as an emerging platform for wastewater remediation owing to their exceptional surface-area-to-volume ratio, unique electrical and chemical properties, quantum size effects, high scalability, and tunable surface functionalities. An array of nanomaterials including noble metal-based nanostructures, transition metal oxide nanomaterials, carbon-based nanomaterials, carbon nanotubes, and graphene/graphene oxide nanomaterials to their novel nanocomposites and nanoconjugates have been attempted as the promising catalysts to overcome environmental dilemmas. In this review, we summarized recent advances in nanostructured materials that are particularly engineered for the remediation of environmental contaminants. The toxicity of various classes of relevant tailored nanomaterials towards human health and the ecosystem along with perspectives is also presented. In our opinion, an overview of the up-to-date advancements on this emerging topic may provide new ideas and thoughts for engineering low-cost and highly-efficient nanostructured materials for the abatement of recalcitrant pollutants for a sustainable environment.

Nanostructured Materials for Artificial Tissue Replacements

This paper review current trends in applications of nanomaterials in tissue engineering. Nanomaterials applicable in this area can be divided into two groups: organic and inorganic. Organic nanomaterials are especially used for the preparation of highly porous scaffolds for cell cultivation and are represented by polymeric nanofibers. Inorganic nanomaterials are implemented as they stand or dispersed in matrices promoting their functional properties while preserving high level of biocompatibility. They are used in various forms (e.g., nano- particles, -tubes and -fibers)-and when forming the composites with organic matrices-are able to enhance many resulting properties (biologic, mechanical, electrical and/or antibacterial). For this reason, this contribution points especially to such type of composite nanomaterials. Basic information on classification, properties and application potential of single nanostructures, as well as complex scaffolds suitable for 3D tissues reconstruction is provided. Examples of practical usage of these structures are demonstrated on cartilage, bone, neural, cardiac and skin tissue regeneration and replacements. Nanomaterials open up new ways of treatments in almost all areas of current tissue regeneration, especially in tissue support or cell proliferation and growth. They significantly promote tissue rebuilding by direct replacement of damaged tissues.

Development of Bionanocomposites Based on PLA, Collagen and AgNPs and Characterization of Their Stability and In Vitro Biocompatibility

Bionanocomposites including poly(lactic acid) (PLA), collagen, and silver nanoparticles (AgNPs) were prepared as biocompatible and stable films. Thermal properties of the PLA-based bionanocomposites indicated an increase in the crystallinity of PLA plasticized due to a small quantity of AgNPs. The results on the stability study indicate the promising contribution of the AgNPs on the durability of PLA-based bionanocomposites. In vitro biocompatibility conducted on the mouse fibroblast cell line NCTC, clone 929, using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed high values of cell viability (>80%) after cell cultivation in the presence of bionanocomposite formulations for 48 h, while the percentages of lactate dehydrogenase (LDH) released in the culture medium were reduced (<15%), indicating no damages of the cell membranes. In addition, cell cycle analysis assessed by flow cytometry indicated that all tested bionanocomposites did not affect cell proliferation and maintained the normal growth rate of cells. The obtained results recommend the potential use of PLA-based bionanocomposites for biomedical coatings.

Nanotechnology for Environmental Remediation: Materials and Applications

Environmental remediation relies mainly on using various technologies (e.g., adsorption, absorption, chemical reactions, photocatalysis, and filtration) for the removal of contaminants from different environmental media (e.g., soil, water, and air). The enhanced properties and effectiveness of nanotechnology-based materials makes them particularly suitable for such processes given that they have a high surface area-to-volume ratio, which often results in higher reactivity. This review provides an overview of three main categories of nanomaterials (inorganic, carbon-based, and polymeric-based materials) used for environmental remediation. The use of these nanomaterials for the remediation of different environmental contaminants-such as heavy metals, dyes, chlorinated organic compounds, organophosphorus compounds, volatile organic compounds, and halogenated herbicides-is reviewed. Various recent examples are extensively highlighted focusing on the materials and their applications.

Functional electrospun fibers for the treatment of human skin wounds

Wounds are trauma induced defects of the human skin involving a multitude of endogenous biochemical events and cellular reactions of the immune system. The healing process is extremely complex and affected by the patient's physiological conditions, potential implications like infectious pathogens and inflammation as well as external factors. Due to increasing incidence of chronic wounds and proceeding resistance of infection pathogens, there is a strong need for effective therapeutic wound care. In this context, electrospun fibers with diameters in the nano- to micrometer range gain increasing interest. While resembling the structure of the native human extracellular matrix, such fiber mats provide physical and mechanical protection (including protection against bacterial invasion). At the same time, the fibers allow for gas exchange and prevent occlusion of the wound bed, thus facilitating wound healing. In addition, drugs can be incorporated within such fiber mats and their release can be adjusted by the material and dimensions of the individual fibers. The review gives a comprehensive overview about the current state of electrospun fibers for therapeutic application on skin wounds. Different materials as well as fabrication techniques are introduced including approaches for incorporation of drugs into or drug attachment onto the fiber surface. Against the background of wound pathophysiology and established therapy approaches, the therapeutic potential of electrospun fiber systems is discussed. A specific focus is set on interactions of fibers with skin cells/tissues as well as wound pathogens and strategies to modify and control them as key aspects for developing effective wound therapeutics. Further, advantages and limitations of controlled drug delivery from fiber mats to skin wounds are discussed and a future perspective is provided.

Composite Membranes of Recombinant Silkworm Antimicrobial Peptide and Poly (L-lactic Acid) (PLLA) for biomedical application

Antimicrobial peptides, produced by innate immune system of hosts in response to invading pathogens, are capable of fighting against a spectrum of bacteria, viruses, fungi, parasites and cancer cells. Here, a recombinant silkworm AMP Bmattacin2 from heterologous expression is studied, indicating a broad spectrum of antibacterial activity and showing selective killing ability towards skin and colon cancer cells over their normal cell counterparts. For the purpose of biomedical application, the electrospinning fabrication technique is employed to load Bmattacin2 into PLLA nanofibrous membrane. In addition to a good compatibility with the normal cells, Bmattacin2 loaded nanofibrous membranes demonstrate instant antibacterial effects and sustained anticancer effects. The cancer cell and bacteria targeting dynamics of recombinant Bmattacin2 are investigated. With these characteristics, PLLA/Bmattacin2 composite membranes have a great potential for developing novel biomedical applications such as cancer therapies and wound healing treatments.

2,3-Dihydroxybenzoic acid electrospun into poly(D,L-lactide) (PDLLA)/poly(ethylene oxide) (PEO) nanofibers inhibited the growth of Gram-positive and Gram-negative bacteria

Widespread emergence of antibiotic-resistant pathogens in recent years has restricted the treatment options for various infectious diseases. Investigation of alternative antimicrobial agents and therapies is thus of utmost importance. Electrospinning of 50 mg/ml 2,3-dihydroxybenzoic acid (DHBA) into 24 % (w/v) poly(D,L-lactide) (PDLLA) and poly(ethylene oxide) (PEO) (1:1) produced nanofibers with an average diameter of 401 ± 122 nm. DHBA released from the nanofibers (315 ± 0.04 µg/ml within 2 h) inhibited the growth of Pseudomonas aeruginosa Xen 5, Klebsiella pneumoniae Xen 39, Escherichia coli Xen 14, Salmonella typhimurium Xen 26, and Staphylococcus aureus strains Xen 30, Xen 31, and Xen 36. The reason for the rapid diffusion of DHBA from PEO:PDLLA may be due to formation of hydrogen bonds between the hydroxyl groups of DHBA and the C=O groups of the PDLLA. DHBA formed a strong interaction with PDLLA and increased the thermal stability of the nanofiber mesh. The DHBA-containing nanofibers were non-hemolytic, suggesting that they may be incorporated in the development of a wound dressing.

Biodegradable polymers for electrospinning: towards biomedical applications

Electrospinning has received much attention recently due to the growing interest in nano-technologies and the unique material properties. This review focuses on recent progress in applying electrospinning technique in production of biodegradable nanofibers to the emerging field of biomedical. It first introduces the basic theory and parameters of nanofibers fabrication, with focus on factors affecting the morphology and fiber diameter of biodegradable nanofibers. Next, commonly electrospun biodegradable nanofibers are discussed, and the comparison of the degradation rate of nanoscale materials with macroscale materials are highlighted. The article also assesses the recent advancement of biodegradable nanofibers in different biomedical applications, including tissue engineering, drug delivery, biosensor and immunoassay. Future perspectives of biodegradable nanofibers are discussed in the last section, which emphasizes on the innovation and development in electrospinning of hydrogels nanofibers, pore size control and scale-up productions.

Electrospun poly(l-lactide) nanofibers loaded with paclitaxel and water-soluble fullerenes for drug delivery and bioimaging

Multifunctional composite nanofibers inhibited the proliferation of HepG-2 cells effectively and reflected the growth state of cells clearly.

Tissue engineering and regenerative medicine -where do we stand?

Tissue Engineering (TE) in the context of Regenerative Medicine (RM) has been hailed for many years as one of the most important topics in medicine in the twenty-first century. While the first clinically relevant TE efforts were mainly concerned with the generation of bioengineered skin substitutes, subsequently TE applications have been continuously extended to a wide variety of tissues and organs. The advent of either embryonic or mesenchymal adult stem-cell technology has fostered many of the efforts to combine this promising tool with TE approaches and has merged the field into the term Regenerative Medicine. As a typical example in translational medicine, the discovery of a new type of cells called Telocytes that have been described in many organs and have been detected by electron microscopy opens another gate to RM. Besides cell-therapy strategies, the application of gene therapy combined with TE has been investigated to generate tissues and organs. The vascularization of constructs plays a crucial role besides the matrix and cell substitutes. Therefore, novel in vivo models of vascularization have evolved allowing axial vascularization with subsequent transplantation of constructs. This article is intended to give an overview over some of the most recent developments and possible applications in RM through the perspective of TE achievements and cellular research. The synthesis of TE with innovative methods of molecular biology and stem-cell technology appears to be very promising.