Adsorption of bovine serum albumin (BSA) by bare magnetite nanoparticles with surface oxidative impurities that prevent aggregation

Bare, uncoated magnetite nanoparticles, synthesized using an electrochemical surfactant-free synthesis, have highly oxidized surfaces that prevent aggregation. These particles have demonstrated highly intriguing biological activity showing extremely potent antibiotic activity against both gram-positive and gram-negative bacteria with little toxicity to rats. This difference in activity could be ascribed to the nature of the protein corona. In this study the kinetics and thermodynamics of the binding of bovine serum albumin, used as a model serum protein, to these magnetite nanoparticles was analyzed. There is no significant change in particle diameter by dynamic light scattering following adsorption indicating corona formation does not induce aggregation. The maximum adsorption capacity of the particles was determined to be 300 mg of BSA/g of magnetite. The particles are able to adsorb 90% of the BSA at protein concentrations as high as 500 mg/L. The adsorption is best described using a pseudo-second-order model and a Langmuir Type III isotherm model. Thermodynamic analysis showed that the process is entropically driven and is spontaneous at all tested temperatures and conditions. However, it appears to be a weak to moderate physical adsorption. This moderate binding affinity could indicate the differential biological activity of these particles towards bacteria and mammalian cells and further support the contention that these are potentially useful new tools for targeting antibiotic-resistant bacteria

Graphene-Based Polymer Composites for Flexible Electronic Applications

Graphene-based nanomaterials have gained a lot of interest over the last years in flexible electronics due to their exceptional electrical, mechanical, and optoelectronic properties, as well as their potential of surface modification. Their flexibility and processability make them suitable for electronic devices that require bending, folding, and stretching, which cannot be fulfilled by conventional electronics. These nanomaterials can be assembled with various types of organic materials, including polymers, and biomolecules, to generate a variety of nanocomposites with greater stretchability and healability, higher stiffness, electrical conductivity, and exceptional thermal stability for flexible lighting and display technologies. This article summarizes the main characteristics and synthesis methods of graphene, its oxidized form graphene oxide (GO), and reduced GO derivative, as well as their corresponding polymeric composites, and provides a brief overview about some recent examples of these nanocomposites in flexible electronic applications, including electrodes for solar cells and supercapacitors, electronic textiles, and transistors

LbL Nano-Assemblies: A Versatile Tool for Biomedical and Healthcare Applications

Polyelectrolytes (PEs) have been the aim of many research studies over the past years. PE films are prepared by the simple and versatile layer-by-layer (LbL) approach using alternating assemblies of polymer pairs involving a polyanion and a polycation. The adsorption of the alternating PE multiple layers is driven by different forces (i.e., electrostatic interactions, H-bonding, charge transfer interactions, hydrophobic forces, etc.), which enable an accurate control over the physical properties of the film (i.e., thickness at the nanoscale and morphology). These PE nano-assemblies have a wide range of biomedical and healthcare applications, including drug delivery, protein delivery, tissue engineering, wound healing, and so forth. This review provides a concise overview of the most outstanding research on the design and fabrication of PE nanofilms. Their nanostructures, molecular interactions with biomolecules, and applications in the biomedical field are briefly discussed. Finally, the perspectives of further research directions in the development of LbL nano-assemblies for healthcare and medical applications are highlighted

L-tryptophan adsorption differentially changes the optical behaviour of pseudo-enantiomeric cysteine-functionalized quantum dots: Towards chiral fluorescent biosensors

Water-soluble chiral graphene quantum dots (GQDs) with a strong blue emission were synthesized by covalently immobilizing l-cysteine or d-cysteine onto the GQDs. Either the amine or the thiol group of cysteine was used to make the bond through amide coupling or thiol-ene click chemistry respectively. The functionalized chiral GQDs were the characterized by FT-IR and UV–vis. The enantiomeric pairs exhibit equal but opposite bands in circular dichroism spectra suggesting that there is no difference in the efficacy of conjugation. The fluorescent response of these chiral GQDs when exposed to l-tryptophan was then studied. The fluorescence of the amide-conjugated GQDs was quenched with the addition of l-Trp regardless of which enantiomer of cysteine was present on the surface. The thiol-linked d- Cys GQDs fluorescence was also quenched on exposure to l-Trp, but the fluorescence of the thiol-linked l-Cys GQDs was unaffected under the same conditions

Detecting Mercury (II) and Thiocyanate Using “Turn-on” Fluorescence of Graphene Quantum Dots

In this work, 1.8 nm graphene quantum dots (GQDs), exhibiting bright blue fluorescence, were prepared using a bottom-up synthesis from citric acid. The fluorescence of the GQDs could be almost completely quenched (about 96%) by adding Hg2+. Quenching was far less efficient with other similar heavy metals, Tl+, Pb2+ and Bi3+. Fluorescence could be near quantitatively restored through the introduction of thiocyanate. This “turn-on” fluorescence can thus be used to detect both or either environmental and physiological contaminants mercury and thiocyanate and could prove useful for the development of simple point-of-care diagnostics in the future. [Figure not available: see fulltext.]

Nanomaterials for the Diagnosis and Treatment of Urinary Tract Infections

The diagnosis and treatment of urinary tract infections (UTIs) remain challenging due to the lack of convenient assessment techniques and to the resistance to conventional antimicrobial therapy, showing the need for novel approaches to address such problems. In this regard, nanotechnology has a strong potential for both the diagnosis and therapy of UTIs via controlled delivery of antimicrobials upon stable, effective and sustained drug release. On one side, nanoscience allowed the production of various nanomaterial-based evaluation tools as precise, effective, and rapid procedures for the identification of UTIs. On the other side, nanotechnology brought tremendous breakthroughs for the treatment of UTIs based on the use of metallic nanoparticles (NPs) for instance, owing to the antimicrobial properties of metals, or of surface-tailored nanocarriers, allowing to overcome multidrug-resistance and prevent biofilm formation via targeted drug delivery to desired sites of action and preventing the development of cytotoxic processes in healthy cells. The goal of the current study is therefore to present the newest developments for the diagnosis and treatment of UTIs based on nanotechnology procedures in relation to the currently available techniques

Synthesis, physical characterization, antifungal and antibacterial activity of oleic acid-capped nanomagnetite and cobalt-doped nanomagnetite

Nanoparticles, 10-14 nm, consisting of either Fe3O4 or Co0.2Fe2.8O4 stabilized with oleic acid, were prepared using solution combustion. Their structural and magnetic properties were examined using X-ray diffractometry, scanning electron microscopy, vibrating sample magnetometry, and Fourier-transform infrared spectroscopy. The properties of both sets of materials are similar except the cobalt-doped particles are considerably less magnetic. The in vitro inhibitory activities of the nanoparticles were assessed against pathogenic bacteria Shigella dysenteriae, Klebsiella pneumoniae, Acinetobacter baumannii, Streptococcus pyogenes, and pathogenic fungi and molds Candida albicans, Fusarium oxysporum and Aspergillus fumigatus. The magnetite nanoparticles were moderately effective against all tested pathogens, but the activity of the cobalt-doped nanoparticles was significantly lower, possibly due to an interruption of the Fenton reaction at the bacterial membrane. This work suggests that potentially doping magnetite with stronger metal oxidants may instead enhance their antimicrobial effects

Antineoplastic effect of paclitaxel-loaded polymeric nanocapsules on malignant human ovarian carcinoma cells (SKOV-3)

Drug resistance is the main responsible for chemotherapy failure in ovarian cancer treatment. In this study, we looked at increasing the anticancer effect of paclitaxel (PTX) through its encapsulation in novel polymeric nanocapsules to develop a novel, less invasive PTX-loaded nano-delivery system. These were synthesized by a microemulsion-based methodology, and their particle size and shapes determined using dynamic light scattering (DLS) and field emission scanning electron microscopy (FESEM). The synthesized PTX-loaded polymeric nanocapsules showed spherical morphology with approximately ca. 18 nm. In vitro cytotoxicity analysis of free administered PTX, bare and PTX-loaded polymeric nanocpasules by means of the MTT assay showed that much lower concentration of PTX loaded inside polymeric nanocapsules (2.2 µg/ml) were needed to achieve a similar therapeutic activity than the free administered drug (14.4 µg/ml). Polymer nanocapsule encapsulation of PTX then improved the therapeutic efficacy as shown by the reduction of IC50 concentration. MYC, MECOM, PRKCl gene and caspases-3, −8, and −9 protein expressions involved in the apoptotic pathway after the treatment of SKOV-3 cells with PTX-loaded polymeric nanocapsules were assessed by qRT-PCR and fluorometric assay, respectively. The expression level of MECOM increased 1.67 times upon administration of PTX-loaded polymeric nanocapsules compared with untreated SKOV-3 cancer cells as the control group (P < 0.001); conversely, MYC and PRKCl gene expressions were 0.40 and 0.45 times lower compared to control cancerous cells (p < 0.001). The expression of caspase-3, caspase-8, and caspase-9 proteins also significantly increased after the administration of PTX-loaded polymeric nanocapsules to cancer cells (p ≤ 0.001). On the other hand, fluorescence microscopy analysis showed nuclei fragmentation after administration of 24.1 μg/mL of PTX-loaded polymeric nanocapsules, which is accompanied by morphological cell alterations, confirming the cytostatic activity of the nanoformulation. Therefore, the synthesized PTX-loaded polymer nanocapsules could be promise and potential nano-delivery system for PTX delivery in ovarian cancer chemotherapyThe University of Zabol, Islamic Republic of Iran, and Javid Biotechnology Company (JBC, Iran) are highly acknowledged. The authors are grateful to Dr. Asgari in the Javid Biotechnology Company (JBC, Iran). P.T. also thanks Agencia Estatal de Investigación (AEI) by project PID2019-109517RB-I00 and Xunta de Galicia ED431C 2022/18. ERDF funds are also acknowledgedS

Novel Carboxymethyl cellulose-based hydrogel with core-shell Fe3O4@SiO2 nanoparticles for quercetin delivery

A nanocomposite composed of carboxymethyl cellulose (CMC) and core&#8211;shell nanoparticles of Fe3O4@SiO2 was prepared as a pH-responsive nanocarrier for quercetin (QC) delivery. The nanoparticles were further entrapped in a water-in-oil-in-water emulsion system for a sustained release profile. The CMC/Fe3O4@SiO2/QC nanoparticles were characterized using dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), a field emission scanning electron microscope (FE-SEM), and a vibrating sample magnetometer (VSM) to obtain insights into their size, stability, functional groups/chemical bonds, crystalline structure, morphology, and magnetic properties, respectively. The entrapment and loading efficiency were slightly improved after the incorporation of Fe3O4@SiO2 NPs within the hydrogel network. The dialysis method was applied for drug release studies. It was found that the amount of QC released increased with the decrease in pH from 7.4 to 5.4, while the sustained-release pattern was preserved. The A549 cell line was chosen to assess the anticancer activity of the CMC/Fe3O4@SiO2/QC nanoemulsion and its components for lung cancer treatment via an MTT assay. The L929 cell line was used in the MTT assay to determine the possible side effects of the nanoemulsion. Moreover, a flow cytometry test was performed to measure the level of apoptosis and necrosis. Based on the obtained results, CMC/Fe3O4@SiO2 can be regarded as a novel promising system for cancer therap

Improving quercetin anticancer activity through a novel polyvinylpyrrolidone/polyvinyl alcohol/TiO2 nanocomposite

A hydrogel nanocomposite comprising polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and titanium oxide (TiO2) was prepared and encapsulated in a double emulsion as a pH-triggered delivery vehicle for quercetin (QC), an antitumor drug. Dynamic light scattering (DLS) was used to estimate the size and confirm the stability of QC-loaded nanoparticles. The interactions between the nanocomposite components, its crystalline structure and the morphology of the nanoparticles were characterized through Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. Drug loading and encapsulation efficiency significantly improved after incorporation of TiO2, which corroborates the beneficial effect of this component. In vitro release experiments indicated the pH-responsivity of the nanocarrier, with higher amount of QC released in an acidic medium than at neutral pH. Due to the presence of a double emulsion, the release pattern was sustained and gradual in both environments. Cellular experiments including MTT assay and flow cytometry were conducted using U87 cell line to compare the anticancer activity of free QC and QCloaded nanoparticles. MTT assay was also performed on a noncancerous cell line (L929) to assess potential side effects of the drug release system. The results obtained herein confirm the suitability of the developed nanocarrier as an efficient drug delivery vehicle for tumor therapy.Comunidad de Madri