Gold, Silver and Iron Oxide Nanoparticles: Synthesis and Bionanoconjugation Strategies Aimed at Electrochemical Applications

Investigating and Optimizing Insulin Partitioning with Conjugated Au Nanoparticles in Aqueous Two-Phase Systems Using Response Surface Methodology

This study investigated the impact of bioconjugation on the partitioning of insulin, a clinically valuable protein, in an aqueous two-phase system. Gold nanoparticles of different sizes were synthesized and conjugated with insulin. Analysis of the conjugated insulin showed that the insulin remains fully active. Conjugated gold nanoparticles (AuNPs/insulin) were used in polyethylene glycol (PEG)-dextran aqueous two-phase systems to investigate the effect of pH, PEG and dextran molecular weights, PEG and dextran concentrations, AuNPs/insulin dosage, and nanoparticle size on the partition coefficient. These systems were chosen for their biocompatibility and low toxicity. Response surface methodology with D-optimal design was used to model and optimize these systems and their affected parameters. At the optimum condition of a pH = 8 system containing 21% PEG 4000, 5% dextran 100,000, and 100 IU AuNPs/insulin, the partition coefficient of AuNPs/insulin was found to be 192.96, which is in agreement with the empirical partition coefficient of 189.2. This is significantly higher than the partition coefficient of free insulin in a similar system. This approach could be used to overcome limitations in the feasibility of aqueous two-phase systems for industrial-scale purification of biomolecules and biopharmaceuticals.

The Promise of Metal-Doped Iron Oxide Nanoparticles as Antimicrobial Agent

Antibiotic resistance (AMR) is one of the pressing global public health concerns and projections indicate a potential 10 million fatalities by the year 2050. The decreasing effectiveness of commercially available antibiotics due to the drug resistance phenomenon has spurred research efforts to develop potent and safe antimicrobial agents. Iron oxide nanoparticles (IONPs), especially when doped with metals, have emerged as a promising avenue for combating microbial infections. Like IONPs, the antimicrobial activities of doped-IONPs are also linked to their surface charge, size, and shape. Doping metals on nanoparticles can alter the size and magnetic properties by reducing the energy band gap and combining electronic charges with spins. Furthermore, smaller metal-doped nanoparticles tend to exhibit enhanced antimicrobial activity due to their higher surface-to-volume ratio, facilitating greater interaction with bacterial cells. Moreover, metal doping can also lead to increased charge density in magnetic nanoparticles and thereby elevate reactive oxygen species (ROS) generation. These ROS play a vital role to disrupt bacterial cell membrane, proteins, or nucleic acids. In this review, we compared the antimicrobial activities of different doped-IONPs, elucidated their mechanism(s), and put forth opinions for improved biocompatibility.

Boosting the integration of cell membrane-nanomaterial hybrids via dextran-mediated dynamic dispersion system to capture bioactive compounds in natural products

Efficient integration is a prerequisite for the application of cell membrane-nanomaterial hybrids (CN hybrids) in bioanalysis, however, the poor dispersity of nanomaterials limits the development of this technology. Although the traditional hydrophilic modification method could improve the dispersity of nanomaterials, it would hinder the coating of the cell membrane, thus making it unsuitable for the integration of CN hybrids. Herein, a method has been proposed to improve the integration efficiency of CN hybrids from a different perspective, that is, establishing a dynamic dispersion system to enhance the interfacial interaction between cell membranes and nanomaterials. Specifically, magnetic graphene oxide (MGO) nanosheets were used as the model carrier and HepG2 cells were used as the source for membrane coating. The addition of the macromolecular stabilizer dextran to the integration process enhanced the dispersity of MGO and avoided the resistance to membrane coating caused by surface modification. Intriguingly, MGO in the dynamic dispersion system showed superior membrane coating ability as compared to hydrophilic modification methods, resulting in the more efficient integration of CN hybrids and greater sensitivity in capturing bioactive compounds from natural products. The proposed design principle provides a brand-new perspective for optimizing the behavior of CN hybrids and can improve the effectiveness of CN hybrids in bioanalytical applications.

Comparison of the effects of AgNPs on the morphological and mechanical characteristics of cancerous cells

Currently, silver nanoparticles (AgNPs) are the most produced nanoparticles in global market and have been widely utilized in the biomedical field. Here, we investigated the morphological and mechanical effects of AgNPs on cancerous cells of A549 cells and SMMC-7721 cells with atomic force microscope (AFM). The influence of AgNPs on the morphological properties and mechanical properties of cancerous cells were characterized utilizing the force-volume (FV) mode and force spectroscopy (FS) mode of AFM measurement. We mainly focus on the comparison of the effects of AgNPs on the two types of cancerous cells based on the fitting results of calculating the Young's moduli utilizing the Sneddon model. The results showed that the morphology changed little, but the mechanical properties of height, roughness, adhesion force and Young's moduli of two cancerous cells varied significantly with the stimulation of different concentrations of AgNPs. This research has provided insights into the classification and characterization of the effects of the various concentrations of AgNPs on the cancerous cells in vitro by utilizing AFM methodologies for disease therapy.

Non-medicinal parts of safflower (bud and stem) mediated sustainable green synthesis of silver nanoparticles under ultrasonication: optimization, characterization, antioxidant, antibacterial and anticancer potential

The flower of safflower is widely used in Chinese herbal preparations and the non-medicinal parts have been applied to develop a sustainable green method, where AgNPs were generated using a mixture of leaf and stem after 12 h of incubation in the dark. In this study, we intend to improve the efficiency of the reduction reaction and optimize this green method by selecting other non-medicinal parts, such as the bud and the pure stem, evaluating the biosynthesis parameters and harnessing the assistance of ultrasonication. Visual observation and UV-vis spectroscopy confirmed that both safflower stem (SS) and bud (SB) mediated AgNPs (SS-AgNPs and SB-AgNPs, respectively) could be produced rapidly over time under ultrasonication. An alkaline solution could accelerate the formation of SS-AgNPs and SB-AgNPs with greater surface loads. SS-AgNPs and SB-AgNPs of small size could be obtained at pH 8.0 and 10.0, respectively. Large concentrations of SS and SB extract are also beneficial for forming AgNPs of small size. It is in acid and neutral solutions that monodispersed SS-AgNPs and SB-AgNPs can be generated. Characterization of selectively synthesized SS-AgNPs and SB-AgNPs demonstrated their spherical shape with the actual size below 30 nm covered by anions. Both SS-AgNPs and SB-AgNPs exhibited potent antioxidant and antibacterial activity. The MIC values of SS-AgNPs for S. aureus and E. coli were 12.5 and 25.0 μg mL^-1, respectively, slightly superior to SB-AgNPs. In an in vitro anticancer assay, both kinds of AgNPs show potent toxicity action against the SW620 cell line with IC₅₀ values of 5.4 and 10.6 μg mL^-1, respectively. However, only SS-AgNPs reveal an inhibitory action against the HeLa cell line, where the IC₅₀ is found to be 26.8 μg mL^-1. These results provide experimental proof that the assistance of ultrasonication and adjusting the process parameters are efficient methods for promoting the reduction reaction, and both SS and SB mediated AgNPs could serve as a promising antioxidant, antibacterial and anticancer agents.

Gold Nanoparticle Drug Delivery System: Principle and Application

In recent years, gold nanoparticles (GNPs) have gradually become a major choice of drug delivery cargoes due to unique properties. Compared to traditional bulk solid gold, GNPs have basic physical and chemical advantages, such as a larger surface area-to-volume ratio and easier surface modification. Furthermore, these have excellent biocompatibility, can induce the directional adsorption and enrichment of biological macromolecules, help retain biological macromolecule activity, and cause low harm to the human body. All these make GNPs good drug delivery cargoes. The present study introduces the properties of GNPs, including factors that affect the properties and synthesis. Then, focus was given on the application in drug delivery, not only on the molecular mechanism, but also on the clinical application. Furthermore, the properties and applications of peptide GNPs were also introduced. Finally, the challenges and prospects of GNPs for drug delivery were summarized.

Bioactive Chitosan-Based Organometallic Scaffolds for Tissue Engineering and Regeneration

Captivating achievements in developing advanced hybrid biostructures through integrating natural biopolymers with inorganic materials (e.g., metals and metalloids) have paved the way towards the application of bioactive organometallic scaffolds (OMSs) in tissue engineering and regenerative medicine (TERM). Of various biopolymers, chitosan (CS) has been used widely for the development of bioactive OMSs, in large part due to its unique characteristics (e.g., biocompatibility, biodegradability, surface chemistry, and functionalization potential). In integration with inorganic elements, CS has been used to engineer advanced biomimetic matrices to accommodate both embedded cells and drug molecules and serve as scaffolds in TERM. The use of the CS-based OMSs is envisioned to provide a new pragmatic potential in TERM and even in precision medicine. In this review, we aim to elaborate on recent achievements in a variety of CS/metal, CS/metalloid hybrid scaffolds, and discuss their applications in TERM. We also provide comprehensive insights into the formulation, surface modification, characterization, biocompatibility, and cytotoxicity of different types of CS-based OMSs.

Green Fabrication of Bioactive Silver Nanoparticles Using Mentha pulegium Extract under Alkaline: An Enhanced Anticancer Activity

Fabrication of silver nanoparticles (AgNPs) using Chinese herbal medicine is popular as the bioactive components included in them would generate potential synergistic effect with the metal nanoparticles. The leaf of Mentha pulegium, whose extract contains a range of phytochemicals and exhibits a wide spectrum of bioactivities, is used as Chinese herbal medicine after drying naturally. Thus, the green synthesis of AgNPs using Mentha pulegium has aroused interests from analysts. However, the biosynthesis of AgNPs under alkaline conditions and the biological activities remain elusive, where alkaline conditions may influence the physicochemical properties and the biological activities of biosynthesized AgNPs. In this study, we were stimulated to fabricate bioactive AgNPs using Mentha pulegium extract under alkaline conditions, accompanied by a systematic evaluation on the effect of biosynthesis parameters on the formation, average size, and polydispersity of AgNPs. Our results showed that alkaline conditions could accelerate the formation of AgNPs with a small average size but at a disadvantage to the polydispersity. Additionally, the as-prepared AgNPs had a hexagonal structure and spherical shape with an average size of 15.7 ± 0.1 nm, existing in the monodispersed form and revealing a high degree of stability. The AgNPs exhibited potent antioxidant and significant inhibitory activity for both bacterial and cancer cell lines. The MIC values of AgNPs for Staphylococcus aureus and Escherichia coli were both 50.0 μg·mL-1, and the IC50 values for HCT116, HepG2, and HeLa cells were 9.0, 14.5, and 31.5 μg·mL-1, respectively. The AgNPs biosynthesized using M. pulegium under alkaline conditions, which had a smaller size and more surface loads, are entirely different with those synthesized under acidic conditions, and the anticancer activity increased significantly. The internalization of AgNPs inside these five cells displayed a variant trend with variable AgNPs concentrations, suggesting the different mechanism of cell death. For two pathogens, HCT116 and HepG2 cancer cell lines, both cell wall and intracellular damage may be responsible for the cell death. However, for Hela cell line the cell death may be rooted in oxidative stress or intracellular penetration. These results confirmed that the AgNPs biosynthesized from M. pulegium extract under alkaline conditions would act as better anticancer agents in biomedicine.

Green Synthesis of Magnetic Nanoparticles Using Satureja hortensis Essential Oil toward Superior Antibacterial/Fungal and Anticancer Performance

The biological synthesis of nanoparticles, due to their environmental and biomedical properties, has been of particular interest to scientists and physicians. Here, iron nanoparticles (FeNPs) were synthesized using Satureja hortensis essential oil. Then, the chemical, functional, and morphological properties of these nanoparticles were characterized by typical experiments such as Uv-Vis, FTIR, XRD, FE-SEM, PSA, zeta potential, EDX, and EDX mapping. The results indicated Fe nanoparticles' formation with a cubic morphological structure and a particle size in the range of 9.3-27 nm. The antimicrobial effects of these nanoparticles were further evaluated using disc diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungal concentration (MFC) against two gram-positive bacterial strains (Staphylococcus aureus and Corynebacterium glutamicum), two gram-negative bacterial strains (Pseudomonas aeruginosa and Escherichia coli), and one fungus species Candida albicans. The results showed that green-synthesized Fe nanoparticles possessed higher antimicrobial properties than Satureja hortensis essential oil against selected pathogenic microorganisms, especially Gram-negative bacteria. Finally, the anticancer effect of these Fe nanoparticles was investigated on human cancer cells, K-562, and MCF-7, by the MTT assay. The results showed the anticancer effect of these nanoparticles against selected cell lines.

Synthesis of Nanoparticles by Spark Discharge as a Facile and Versatile Technique of Preparing Highly Conductive Pt Nano-Ink for Printed Electronics

A cost-effective, scalable and versatile method of preparing nano-ink without hazardous chemical precursors is a prerequisite for widespread adoption of printed electronics. Precursor-free synthesis by spark discharge is promising for this purpose. The synthesis of platinum nanoparticles (PtNPs) using a spark discharge under Ar, N2, and air has been investigated to prepare highly conductive nano-ink. The size, chemical composition, and mass production rate of PtNPs significantly depended on the carrier gas. Pure metallic PtNPs with sizes of 5.5 ± 1.8 and 7.1 ± 2.4 nm were formed under Ar and N2, respectively. PtNPs with sizes of 18.2 ± 9.0 nm produced using air consisted of amorphous oxide PtO and metallic Pt. The mass production rates of PtNPs were 53 ± 6, 366 ± 59, and 490 ± 36 mg/h using a spark discharge under Ar, N2, and air, respectively. It was found that the energy dissipated in the spark gap is not a significant parameter that determines the mass production rate. Stable Pt nano-ink (25 wt.%) was prepared only on the basis of PtNPs synthesized under air. Narrow (about 30 μm) and conductive Pt lines were formed by the aerosol jet printing with prepared nano-ink. The resistivity of the Pt lines sintered at 750 °C was (1.2 ± 0.1)·10-7 Ω·m, which is about 1.1 times higher than that of bulk Pt.

Recent Advancement in Nanotechnology-Based Drug Delivery System Against Viral Infections

In the last few decades, the exponential rise in the incidence of viral infections sets a global health emergency across the world. The biomimetic architecture, the ability to hijack host immune responses, continuous antigen shifting, and drafting are the major critical factors that are responsible for the unavailability of a concrete therapeutic regimen against viral infections. Further, inappropriate pharmacodynamic physicochemical and biological parameters such as low aqueous solubility, poor permeability, high affinity for plasm proteins, short biological half-lives, and fast elimination from the systemic circulation are the major critical factors that govern the suboptimal drug concentration at the target site that leads to the development of drug resistance. To address this issue, nanotechnology-based drug delivery approach is emerged as an altering method to attain the optimal drug concentration at the target site for a prolonged period by integrating the nanoengineering tools in the synthesis of nanoparticles. Nanodimensional configuration with enhanced permeability and retention effect, increased surface-area-to-volume ratio, provision for surface functionalization, etc., are the privileged aspects that make it an effective drug delivery system for dispensing the antiviral therapeutics. However, size, shape, charge, and surface topology of nanoparticles are the greater influential factors that determine target-specific drug delivery, optimum cellular uptake, degree of opsonization by the host immune cells, drug retention time, transcytosis, the extension of biological half-life, in vivo stability, and cytotoxicity. The review will enlighten the elaborative role of nanotechnology-based drug delivery and the major challenging aspect of clinical safety and efficacy.

Magnetic Iron Oxide Nanoparticle (IONP) Synthesis to Applications: Present and Future

Iron oxides are chemical compounds which have different polymorphic forms, including γ-Fe2O3 (maghemite), Fe3O4 (magnetite), and FeO (wustite). Among them, the most studied are γ-Fe2O3 and Fe3O4, as they possess extraordinary properties at the nanoscale (such as super paramagnetism, high specific surface area, biocompatible etc.), because at this size scale, the quantum effects affect matter behavior and optical, electrical and magnetic properties. Therefore, in the nanoscale, these materials become ideal for surface functionalization and modification in various applications such as separation techniques, magnetic sorting (cells and other biomolecules etc.), drug delivery, cancer hyperthermia, sensing etc., and also for increased surface area-to-volume ratio, which allows for excellent dispersibility in the solution form. The current methods used are partially and passively mixed reactants, and, thus, every reaction has a different proportion of all factors which causes further difficulties in reproducibility. Direct active and complete mixing and automated approaches could be solutions to this size- and shape-controlled synthesis, playing a key role in its exploitation for scientific or technological purposes. An ideal synthesis method should be able to allow reliable adjustment of parameters and control over the following: fluctuation in temperature; pH, stirring rate; particle distribution; size control; concentration; and control over nanoparticle shape and composition i.e., crystallinity, purity, and rapid screening. Iron oxide nanoparticle (IONP)-based available clinical applications are RNA/DNA extraction and detection of infectious bacteria and viruses. Such technologies are important at POC (point of care) diagnosis. IONPs can play a key role in these perspectives. Although there are various methods for synthesis of IONPs, one of the most crucial goals is to control size and properties with high reproducibility to accomplish successful applications. Using multiple characterization techniques to identify and confirm the oxide phase of iron can provide better characterization capability. It is very important to understand the in-depth IONP formation mechanism, enabling better control over parameters and overall reaction and, by extension, properties of IONPs. This work provides an in-depth overview of different properties, synthesis methods, and mechanisms of iron oxide nanoparticles (IONPs) formation, and the diverse range of their applications. Different characterization factors and strategies to confirm phase purity in the IONP synthesis field are reviewed. First, properties of IONPs and various synthesis routes with their merits and demerits are described. We also describe different synthesis strategies and formation mechanisms for IONPs such as for: wustite (FeO), hematite (α-Fe2O3), maghemite (ɤ-Fe2O3) and magnetite (Fe3O4). We also describe characterization of these nanoparticles and various applications in detail. In conclusion, we present a detailed overview on the properties, size-controlled synthesis, formation mechanisms and applications of IONPs.

Magnetite Nanoparticles and Essential Oils Systems for Advanced Antibacterial Therapies

Essential oils (EOs) have attracted considerable interest in the past few years, with increasing evidence of their antibacterial, antiviral, antifungal, and insecticidal effects. However, as they are highly volatile, the administration of EOs to achieve the desired effects is challenging. Therefore, nanotechnology-based strategies for developing nanoscaled carriers for their efficient delivery might offer potential solutions. Owing to their biocompatibility, biodegradability, low toxicity, ability to target a tissue specifically, and primary structures that allow for the attachment of various therapeutics, magnetite nanoparticles (MNPs) are an example of such nanocarriers that could be used for the efficient delivery of EOs for antimicrobial therapies. The aim of this paper is to provide an overview of the use of EOs as antibacterial agents when coupled with magnetite nanoparticles (NPs), emphasizing the synthesis, properties and functionalization of such NPs to enhance their efficiency. In this manner, systems comprising EOs and MNPs could offer potential solutions that could overcome the challenges associated with biofilm formation on prosthetic devices and antibiotic-resistant bacteria by ensuring a controlled and sustained release of the antibacterial agents.

Nanobioconjugates for Signal Amplification in Electrochemical Biosensing

Nanobioconjugates are hybrid materials that result from the coalescence of biomolecules and nanomaterials. They have emerged as a strategy to amplify the signal response in the biosensor field with the potential to enhance the sensitivity and detection limits of analytical assays. This critical review collects a myriad of strategies for the development of nanobioconjugates based on the conjugation of proteins, antibodies, carbohydrates, and DNA/RNA with noble metals, quantum dots, carbon- and magnetic-based nanomaterials, polymers, and complexes. It first discusses nanobioconjugates assembly and characterization to focus on the strategies to amplify a biorecognition event in biosensing, including molecular-, enzymatic-, and electroactive complex-based approaches. It provides some examples, current challenges, and future perspectives of nanobioconjugates for the amplification of signals in electrochemical biosensing.

Projection method as a probe for multiplexing/demultiplexing of magnetically enriched biological tissues

The unmet demand for cheap, accurate, and fast multiplexing of biomarkers has urged nanobiotechnology to prioritize the invention of new biomarkers that make feasible the remote detection, identification, and quantification of biological units, such as regenerative tissues. Here, we introduce a novel approach that highlights magnetic nanowires (MNWs) with such capabilities. This method employs the stable magnetization states of MNWs as a unique characteristic that can be realized by projecting the MNWs' switching field on the backward field (P_Hb), also known as the irreversible switching field. Experimentally, several types of MNWs were directly synthesized inside polycarbonate tissues and their P_Hb characteristics were measured and analyzed. Our results show that the P_Hb gives an excellent identification and quantification characteristic for demultiplexing MNWs embedded in these tissues. Furthermore, this method significantly improves the characterization speed by a factor of 50×–100× that makes it superior to the current state of the art that ceased the progression of magnetic nanoparticles in multiplexing/demultiplexing applications.

Different polycarbonate tissues were enriched using magnetic nanowires with diverse magnetic signatures. Projection method successfully identifies and quantifies the complex combinations of the magnetically enriched polycarbonate tissues.