Plant Fibers as Composite Reinforcements for Biomedical Applications.

Plant fibers possess high strength, high fracture toughness and elasticity, and have proven useful because of their diversity, versatility, renewability, and sustainability. For biomedical applications, these natural fibers have been used as reinforcement for biocomposites to infer these hybrid biomaterials mechanical characteristics, such as stiffness, strength, and durability. The reinforced hybrid composites have been tested in structural and semi-structural biodevices for potential applications in orthopedics, prosthesis, tissue engineering, and wound dressings. This review introduces plant fibers, their properties and factors impacting them, in addition to their applications. Then, it discusses different methodologies used to prepare hybrid composites based on these widespread, renewable fibers and the unique properties that the obtained biomaterials possess. It also examines several examples of hybrid composites and their biomedical applications. Finally, the findings are summed up and some thoughts for future developments are provided. Overall, the focus of the present review lies in analyzing the design, requirements, and performance, and future developments of hybrid composites based on plant fibers.

Biogenic Selenium Nanoparticles in Biomedical Sciences: Properties, Current Trends, Novel Opportunities and Emerging Challenges in Theranostic Nanomedicine.

Selenium is an important dietary supplement and an essential trace element incorporated into selenoproteins with growth-modulating properties and cytotoxic mechanisms of action. However, different compounds of selenium usually possess a narrow nutritional or therapeutic window with a low degree of absorption and delicate safety margins, depending on the dose and the chemical form in which they are provided to the organism. Hence, selenium nanoparticles (SeNPs) are emerging as a novel therapeutic and diagnostic platform with decreased toxicity and the capacity to enhance the biological properties of Se-based compounds. Consistent with the exciting possibilities offered by nanotechnology in the diagnosis, treatment, and prevention of diseases, SeNPs are useful tools in current biomedical research with exceptional benefits as potential therapeutics, with enhanced bioavailability, improved targeting, and effectiveness against oxidative stress and inflammation-mediated disorders. In view of the need for developing eco-friendly, inexpensive, simple, and high-throughput biomedical agents that can also ally with theranostic purposes and exhibit negligible side effects, biogenic SeNPs are receiving special attention. The present manuscript aims to be a reference in its kind by providing the readership with a thorough and comprehensive review that emphasizes the current, yet expanding, possibilities offered by biogenic SeNPs in the biomedical field and the promise they hold among selenium-derived products to, eventually, elicit future developments. First, the present review recalls the physiological importance of selenium as an oligo-element and introduces the unique biological, physicochemical, optoelectronic, and catalytic properties of Se nanomaterials. Then, it addresses the significance of nanosizing on pharmacological activity (pharmacokinetics and pharmacodynamics) and cellular interactions of SeNPs. Importantly, it discusses in detail the role of biosynthesized SeNPs as innovative theranostic agents for personalized nanomedicine-based therapies. Finally, this review explores the role of biogenic SeNPs in the ongoing context of the SARS-CoV-2 pandemic and presents key prospects in translational nanomedicine.

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications.

Bio-nanotechnology has emerged as an efficient and competitive methodology for the production of added-value nanomaterials (NMs). This review article gathers knowledge gleaned from the literature regarding the biosynthesis of sulfur-based chalcogenide nanoparticles (S-NPs), such as CdS, ZnS and PbS NPs, using various biological resources, namely bacteria, fungi including yeast, algae, plant extracts, single biomolecules, and viruses. In addition, this work sheds light onto the hypothetical mechanistic aspects, and discusses the impact of varying the experimental parameters, such as the employed bio-entity, time, pH, and biomass concentration, on the obtained S-NPs and, consequently, on their properties. Furthermore, various bio-applications of these NMs are described. Finally, key elements regarding the whole process are summed up and some hints are provided to overcome encountered bottlenecks towards the improved and scalable production of biogenic S-NPs.

Natural Biomaterials from Biodiversity for Healthcare Applications.

Natural biomaterials originating during the growth cycles of all living organisms have been used for many applications. They span from bioinert to bioactive materials including bioinspired ones. As they exhibit an increasing degree of sophistication, natural biomaterials have proven suitable to address the needs of the healthcare sector. Here the different natural healthcare biomaterials, their biodiversity sources, properties, and promising healthcare applications are reviewed. The variability of their properties as a result of considered species and their habitat is also discussed. Finally, some limitations of natural biomaterials are discussed and possible future developments are provided as more natural biomaterials are yet to be discovered and studied.

Bimodal Ultrasound and X-ray Bioimaging Properties of Particulate Calcium Fluoride Biomaterial.

Ultrasound (US) and X-ray imaging are diagnostic methods that are commonly used to image internal body structures. Several organic and inorganic imaging contrast agents are commercially available. However, their synthesis and purification remain challenging, in addition to posing safety issues. Here, we report on the promise of widespread, safe, and easy-to-produce particulate calcium fluoride (part-CaF2) as a bimodal US and X-ray contrast agent. Pure and highly crystalline part-CaF2 is obtained using a cheap commercial product. Scanning electron microscopy (SEM) depicts the morphology of these particles, while energy-dispersive X-ray spectroscopy (EDS) confirms their chemical composition. Diffuse reflectance ultraviolet-visible spectroscopy highlights their insulating behavior. The X-ray diffraction (XRD) pattern reveals that part-CaF2 crystallizes in the face-centered cubic cell lattice. Further analyses regarding peak broadening are performed using the Scherrer and Williamson-Hall (W-H) methods, which pinpoint the small crystallite size and the presence of lattice strain. X-ray photoelectron spectroscopy (XPS) solely exhibits specific peaks related to CaF2, confirming the absence of any contamination. Additionally, in vitro cytotoxicity and in vivo maximum tolerated dose (MTD) tests prove the biocompatibility of part-CaF2. Finally, the results of the US and X-ray imaging tests strongly signal that part-CaF2 could be exploited in bimodal bioimaging applications. These findings may shed a new light on calcium fluoride and the opportunities it offers in biomedical engineering.

Sonochemical synthesis of porous gold nano- and microparticles in a Rosette cell.

We report the synthesis of Au nano- and microparticles that relies on α-D-glucose (C6H12O6) as the reducer and stabilizer in a Rosette cell under 20 kHz ultrasound irradiation. The chemical and physical effects of ultrasonic irradiation on the synthesis were investigated. The results showed that an optimum pH is required for the formation of insoluble Au(0) particles. Upon irradiation, low pH yielded Au nanoparticles while high pH resulted in microparticles. The Au surface capping by α-D-glucose hydroxyl and carbonyl groups was confirmed by Fourier transform infrared (FT-IR) spectroscopy. X-ray diffraction (XRD) analysis indicated that the Au particles crystallize within the face-centered-cubic (FCC) cell lattice. Moreover, continuous sonication reduced larger amounts of the Au precursor compared to the intermittent mode. Furthermore, tuning sonication time and mode influences the particle size and porosity as characterized by scanning and transmission electron microscopy. Our results shed a new light into the importance of the experimental and ultrasound parameters in obtaining Au particles of desired features through sonochemistry.

Photochemical Synthesis of Gold and Silver Nanoparticles-A Review.

Nanomaterials have supported important technological advances due to their unique properties and their applicability in various fields, such as biomedicine, catalysis, environment, energy, and electronics. This has triggered a tremendous increase in their demand. In turn, materials scientists have sought facile methods to produce nanomaterials of desired features, i.e., morphology, composition, colloidal stability, and surface chemistry, as these determine the targeted application. The advent of photoprocesses has enabled the easy, fast, scalable, and cost- and energy-effective production of metallic nanoparticles of controlled properties without the use of harmful reagents or sophisticated equipment. Herein, we overview the synthesis of gold and silver nanoparticles via photochemical routes. We extensively discuss the effect of varying the experimental parameters, such as the pH, exposure time, and source of irradiation, the use or not of reductants and surfactants, reagents' nature and concentration, on the outcomes of these noble nanoparticles, namely, their size, shape, and colloidal stability. The hypothetical mechanisms that govern these green processes are discussed whenever available. Finally, we mention their applications and insights for future developments.

Dual Encapsulated Dacarbazine and Zinc Phthalocyanine Polymeric Nanoparticle for Photodynamic Therapy of Melanoma.

PURPOSE: Melanoma is an invasive and very aggressive skin cancer due to its multi-drug resistance that results in poor patient survival. There is a need to test new treatment approaches to improve therapeutic efficacy and reduce side effects of conventional treatments. METHODS: PLA/PVA nanoparticles carrying both Dacarbazine and zinc phthalocyanine was produced by double emulsion technique. The characterization was performed by dynamic light scattering and atomic force microscopy. In vitro photodynamic therapy test assay using MV3 melanoma cells as a model has been performed. In vitro cell viability (MTT) was performed to measure cell toxicity of of nanoparticles with and without drugs using human endothelial cells as a model. The in vivo assay (biodistribution/tissue deposition) has been performed using radiolabeled PLA/PVA NPs. RESULTS: The nanoparticles produced showed a mean diameter of about 259 nm with a spherical shape. The in-vitro photodynamic therapy tests demonstrated that the combination is critical to enhance the therapeutic efficacy and it is dose dependent. The in vitro cell toxicity assay using endothelial cells demonstrated that the drug encapsulated into nanoparticles had no significant toxicity compared to control samples. In-vivo results demonstrated that the drug loading affects the biodistribution of the nanoparticle formulations (NPs). Low accumulation of the NPs into the stomach, heart, brain, and kidneys suggested that common side effects of Dacarbazine could be reduced. CONCLUSION: This work reports a robust nanoparticle formulation with the objective to leveraging the synergistic effects of chemo and photodynamic therapies to potentially suppressing the drug resistance and reducing side effects associated with Dacarbazine. The data corroborates that the dual encapsulated NPs showed better in-vitro efficacy when compared with the both compounds alone. The results support the need to have a dual modality NP formulation for melanoma therapy by combining chemotherapy and photodynamic therapy.

Polytetrafluoroethylene-like Nanoparticles as a Promising Contrast Agent for Dual Modal Ultrasound and X-ray Bioimaging.

Various noninvasive imaging techniques are used to produce deep-tissue and high-resolution images for biomedical research and clinical purposes. Organic and inorganic bioimaging agents have been developed to enhance the resolution and contrast intensity. This paper describes the synthesis of polytetrafluoroethylene-like nanoparticles (PTFE≈ NPs), their characterization, biological activity, and bioimaging properties. Transmission electron microscopy (TEM) images showed the shape and the size of the as-obtained small and ultrasmall PTFE≈ NPs. Fourier transform infrared spectroscopy (FTIR) confirmed the PTFE-like character of the samples. X-ray diffraction (XRD) enabled the determination of the crystallization system, cell lattice, and index of crystallinity of the material in addition to the presence of titania (TiO2) as the contamination. These findings were corroborated by X-ray photoelectron spectroscopy (XPS) that identifies the chemical states of the elements present in the samples along with their atomic percentages allowing the determination of both the purity index of the sample and the nature of the impurities. Additionally, diffuse reflectance ultraviolet-visible spectroscopy (UV-vis) was used to further assess the optical properties of the materials. Importantly, PTFE≈ NPs showed significant in vitro and in vivo biocompatibility. Lastly, PTFE≈ NPs were tested for their ultrasound and X-ray contrast properties. Our encouraging preliminary results open new avenues for PTFE-like nanomaterials as a suitable multifunctional contrast agent for biomedical imaging applications. Combined with suitable surface chemistry and morphology design, these findings shed light to new opportunities offered by PTFE nanoparticles in the ever-booming biomedical field.

Green Synthesis of Selenium and Tellurium Nanoparticles: Current Trends, Biological Properties and Biomedical Applications.

The synthesis and assembly of nanoparticles using green technology has been an excellent option in nanotechnology because they are easy to implement, cost-efficient, eco-friendly, risk-free, and amenable to scaling up. They also do not require sophisticated equipment nor well-trained professionals. Bionanotechnology involves various biological systems as suitable nanofactories, including biomolecules, bacteria, fungi, yeasts, and plants. Biologically inspired nanomaterial fabrication approaches have shown great potential to interconnect microbial or plant extract biotechnology and nanotechnology. The present article extensively reviews the eco-friendly production of metalloid nanoparticles, namely made of selenium (SeNPs) and tellurium (TeNPs), using various microorganisms, such as bacteria and fungi, and plants' extracts. It also discusses the methodologies followed by materials scientists and highlights the impact of the experimental sets on the outcomes and shed light on the underlying mechanisms. Moreover, it features the unique properties displayed by these biogenic nanoparticles for a large range of emerging applications in medicine, agriculture, bioengineering, and bioremediation.

Sugar-Mediated Green Synthesis of Silver Selenide Semiconductor Nanocrystals under Ultrasound Irradiation.

Silver selenide (Ag2Se) is a promising nanomaterial due to its outstanding optoelectronic properties and countless bio-applications. To the best of our knowledge, we report, for the first time, a simple and easy method for the ultrasound-assisted synthesis of Ag2Se nanoparticles (NPs) by mixing aqueous solutions of silver nitrate (AgNO3) and selenous acid (H2SeO3) that act as Ag and Se sources, respectively, in the presence of dissolved fructose and starch that act as reducing and stabilizing agents, respectively. The concentrations of mono- and polysaccharides were screened to determine their effect on the size, shape and colloidal stability of the as-synthesized Ag2Se NPs which, in turn, impact the optical properties of these NPs. The morphology of the as-synthesized Ag2Se NPs was characterized by transmission electron microscopy (TEM) and both α- and ß-phases of Ag2Se were determined by X-ray diffraction (XRD). The optical properties of Ag2Se were studied using UV-Vis spectroscopy and its elemental composition was determined non-destructively using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS). The biological activity of the Ag2Se NPs was assessed using cytotoxic and bactericidal approaches. Our findings pave the way to the cost-effective, fast and scalable production of valuable Ag2Se NPs that may be utilized in numerous fields.

Biomedical Science to Tackle the COVID-19 Pandemic: Current Status and Future Perspectives.

The coronavirus infectious disease (COVID-19) pandemic emerged at the end of 2019, and was caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which has resulted in an unprecedented health and economic crisis worldwide. One key aspect, compared to other recent pandemics, is the level of urgency, which has started a race for finding adequate answers. Solutions for efficient prevention approaches, rapid, reliable, and high throughput diagnostics, monitoring, and safe therapies are needed. Research across the world has been directed to fight against COVID-19. Biomedical science has been presented as a possible area for combating the SARS-CoV-2 virus due to the unique challenges raised by the pandemic, as reported by epidemiologists, immunologists, and medical doctors, including COVID-19's survival, symptoms, protein surface composition, and infection mechanisms. While the current knowledge about the SARS-CoV-2 virus is still limited, various (old and new) biomedical approaches have been developed and tested. Here, we review the current status and future perspectives of biomedical science in the context of COVID-19, including nanotechnology, prevention through vaccine engineering, diagnostic, monitoring, and therapy. This review is aimed at discussing the current impact of biomedical science in healthcare for the management of COVID-19, as well as some challenges to be addressed.

In Vivo Biosynthesis of Inorganic Nanomaterials Using Eukaryotes-A Review.

Bionanotechnology, the use of biological resources to produce novel, valuable nanomaterials, has witnessed tremendous developments over the past two decades. This eco-friendly and sustainable approach enables the synthesis of numerous, diverse types of useful nanomaterials for many medical, commercial, and scientific applications. Countless reviews describing the biosynthesis of nanomaterials have been published. However, to the best of our knowledge, no review has been exclusively focused on the in vivo biosynthesis of inorganic nanomaterials. Therefore, the present review is dedicated to filling this gap by describing the many different facets of the in vivo biosynthesis of nanoparticles (NPs) using living eukaryotic cells and organisms-more specifically, live plants and living biomass of several species of microalgae, yeast, fungus, mammalian cells, and animals. It also highlights the strengths and weaknesses of the synthesis methodologies and the NP characteristics, bio-applications, and proposed synthesis mechanisms. This comprehensive review also brings attention to enabling a better understanding between the living organisms themselves and the synthesis conditions that allow their exploitation as nanobiotechnological production platforms as these might serve as a robust resource to boost and expand the bio-production and use of desirable, functional inorganic nanomaterials.

Special Issue: Biogenic Nanomaterials: Versatility and Applications.

Greener processes have emerged as serious and competitive routes to produce various nanomaterials [...].

A Mechanistic View of the Light-Induced Synthesis of Silver Nanoparticles Using Extracellular Polymeric Substances of Chlamydomonas reinhardtii.

In the current study, extracellular polymeric substances (EPS) of Chlamydomonas reinhardtii and photon energy biosynthetically converted Ag+ to silver nanoparticles (AgNPs). The reaction mechanism began with the non-photon-dependent adsorption of Ag+ to EPS biomolecules. An electron from the EPS biomolecules was then donated to reduce Ag+ to Ag0, while a simultaneous release of H+ acidified the reaction mixture. The acidification of the media and production rate of AgNPs increased with increasing light intensity, indicating the light-dependent nature of the AgNP synthesis process. In addition, the extent of Ag+ disappearance from the aqueous phase and the AgNP production rate were both dependent on the quantity of EPS in the reaction mixture, indicating Ag+ adsorption to EPS as an important step in AgNP production. Following the reaction, stabilization of the NPs took place as a function of EPS concentration. The shifts in the intensities and positions of the functional groups, detected by Fourier-transform infrared spectroscopy (FTIR), indicated the potential functional groups in the EPS that reduced Ag+, capped Ag0, and produced stable AgNPs. Based on these findings, a hypothetic three-step, EPS-mediated biosynthesis mechanism, which includes a light-independent adsorption of Ag+, a light-dependent reduction of Ag+ to Ag0, and an EPS concentration-dependent stabilization of Ag0 to AgNPs, has been proposed.

Individual and Combined Effects of Extracellular Polymeric Substances and Whole Cell Components of Chlamydomonas reinhardtii on Silver Nanoparticle Synthesis and Stability.

The fresh water microalga Chlamydomonas reinhardtii bioreduced Ag⁺ to silver nanoparticles (AgNPs) via three biosynthetic routes in a process that could be a more sustainable alternative to conventionally produced AgNPs. The AgNPs were synthesized in either the presence of whole cell cultures, an exopolysaccharide (EPS)-containing cell culture supernatant, or living cells that had been separated from the EPS-containing supernatant and then washed before being suspended again in fresh media. While AgNPs were produced by all three methods, the washed cultures had no supernatant-derived EPS and produced only unstable AgNPs, thus the supernatant-EPS was shown to be necessary to cap and stabilize the biogenic AgNPs. TEM images showed stable AgNPs were mostly spherical and showed a bimodal size distribution about the size ranges of 3.0 ± 1.3 nm and 19.2 ± 5.0 nm for whole cultures and 3.5 ± 0.6 nm and 17.4 ± 2.6 nm for EPS only. Moreover, selected area electron diffraction pattern of these AgNPs confirmed their polycrystalline nature. FTIR of the as-produced AgNPs identified polysaccharides, polyphenols and proteins were responsible for the observed differences in the AgNP stability, size and shape. Additionally, Raman spectroscopy indicated carboxylate and amine groups were bound to the AgNP surface.

Evaluating microwave-synthesized silver nanoparticles from silver nitrate with life cycle assessment techniques.

Silver Nanoparticles (AgNPs) are well known for applications in electronics and as antimicrobial agents because of their unique optical, electrical, cytotoxic and thermal properties. These nanoparticles can be synthesized via a wide variety of techniques; however, they require the use of hazardous solvents which have very high environmental impacts. Nanoscience researchers have attempted novel synthesis routes that reduce resource requirements and use benign chemicals, while maintaining control over their unique properties. The present study evaluates the potential environmental impacts of one such benign method using Life Cycle Assessment (LCA) techniques which are used to assess the environmental impacts of a product's life through all the stages from raw material extraction to disposal/ recycling. This research evaluates AgNPs which were synthesized using glucose as the reducing agent and food grade corn starch as the stabilizing agent in a microwave-assisted reaction system. GaBi 6.0 software was used to carry out the Life Cycle Impact Assessment on a declared unit of 1 kg of 3.0 ±â€¯1.2 nm diameter AgNPs. The results indicate that the impacts are predominantly on acidification (AP), human health particulate air (HHAP) and human toxicity non-cancer (HTNCP) potentials. These impacts are mainly from the production of silver metal and electricity used. The starch and glucose used to produce AgNPs of 3.0 ±â€¯1.2 nm is shown to have negligible environmental impacts and is therefore considered to be environmentally benign.

High conversion synthesis of <10 nm starch-stabilized silver nanoparticles using microwave technology.

A microwave reaction to convert 99 ± 1% of Ag+ to silver nanoparticles (AgNPs) of size <10 nm within 4.5 min with a specific production rate and energy input of 5.75 mg AgNP L-1 min-1 and 5.45 W mL-1 reaction volume was developed. The glucose reduced and food grade starch stabilized particles remained colloidally stable with less than a 4% change in the surface plasmon resonance band at 425-430 nm at t > 300 days. TEM determined the size of AgNPs, while TEM-EDS and XRD verified elemental composition. The conversion was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES) and thermal gravimetric analysis (TGA). Additionally, the required silver to starch input mass ratio, 1.0:1.3, to produce colloidally stabilized AgNPs is significantly reduced compared to previous studies. The antibacterial activity of freshly prepared AgNPs and AgNPs aged >300 days was demonstrated against E. coli as determined by agar diffusion assays. This result, corroborated by spectrophotometric and TEM measurements, indicates long-term colloidal stability of the product. Thus, this study sustainably produced antibacterial AgNPs from minimal inputs. In the broader context, the current work has quantified a sustainable platform technology to produce sphere-like inorganic nanoparticles with antimicrobial properties.

Biosynthetic Conversion of Ag⁺ to highly Stable Ag° Nanoparticles by Wild Type and Cell Wall Deficient Strains of Chlamydomonas reinhardtii.

In the current study, two different strains of the green, freshwater microalga Chlamydomonas reinhardtii bioreduced Ag⁺ to silver nanoparticles (AgNPs), which have applications in biosensors, biomaterials, and therapeutic and diagnostic tools. The bioreduction takes place in cell cultures of C. reinhardtii at ambient temperature and atmospheric pressure, thus eliminating the need for specialized equipment, harmful reducing agents or the generation of toxic byproducts. In addition to the visual changes in the cell culture, the production of AgNPs was confirmed by the characteristic surface plasmon resonance (SPR) band in the range of 415⁻425 nm using UV-Vis spectrophotometry and further evolution of the SPR peaks were studied by comparing the peak intensity at maximum absorbance over time. X-ray diffraction (XRD) determined that the NPs were Ag°. Micrographs from transmission electron microscopy (TEM) revealed that 97 ± 2% AgNPs were <10 nm in diameter. Ag⁺ to AgNP conversion was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The AgNPs were stable over time in the cell culture media, acetone, NaCl and reagent alcohol solutions. This was verified by a negligible change in the features of the SPR band after t > 300 days of storage at 4 °C.

Biosynthesis of Inorganic Nanoparticles: A Fresh Look at the Control of Shape, Size and Composition.

Several methodologies have been devised for the design of nanomaterials. The "Holy Grail" for materials scientists is the cost-effective, eco-friendly synthesis of nanomaterials with controlled sizes, shapes and compositions, as these features confer to the as-produced nanocrystals unique properties making them appropriate candidates for valuable bio-applications. The present review summarizes published data regarding the production of nanomaterials with special features via sustainable methodologies based on the utilization of natural bioresources. The richness of the latter, the diversity of the routes adopted and the tuned experimental parameters have led to the fabrication of nanomaterials belonging to different chemical families with appropriate compositions and displaying interesting sizes and shapes. It is expected that these outstanding findings will encourage researchers and attract newcomers to continue and extend the exploration of possibilities offered by nature and the design of innovative and safer methodologies towards the synthesis of unique nanomaterials, possessing desired features and exhibiting valuable properties that can be exploited in a profusion of fields.