Bacterial toxicity/compatibility of platinum nanospheres, nanocuboids and nanoflowers

Metallic nano-warriors: Innovations in nanoparticle-based ocular antimicrobials

Eye infection is one of the most important causes of blindness. Due to the particularity of ocular structure, the enhancement of bacteria resistance, and the significant side effects of long-term medication, it is difficult to treat ocular antimicrobial diseases. The efficacy of medications currently employed is progressively becoming more restricted. The research and development of novel antimicrobial drugs is imperative and imminent in order to overcome the bottleneck problem. Metal nanoparticles have been developed rapidly in the field of biomedicine because of their brilliant antibacterial activity, long-lasting effect, and great bioavailability. Efficacy and biosafety proven in in vitro and in vivo experiments demonstrate the promising prospect of metal nanoparticles for ocular antimicrobial therapy. Based on the development status of antibacterial metal nanoparticles in ophthalmology, we summarized the antibacterial mechanism of metal nanoparticles and the application of nano-antibacterial drugs in this field, emphasizing their advantages over conventional drugs, thus guiding clinical ophthalmic antibacterial therapy.

Assessing anticancer properties of PEGylated platinum nanoparticles on human breast cancer cell lines usingin-vitroassays

This study describes the in-vitro cytotoxic effects of PEG-400 (Polyethylene glycol-400)-capped platinum nanoparticles (PEGylated Pt NPs) on both normal and cancer cell lines. Structural characterization was carried out using x-ray diffraction and Raman spectroscopy with an average crystallite size 5.7 nm, and morphological assessment using Scanning electron microscopy (SEM) revealed the presence of spherical platinum nanoparticles. The results of energy-dispersive x-ray spectroscopy (EDX) showed a higher percentage fraction of platinum content by weight, along with carbon and oxygen, which are expected from the capping agent, confirming the purity of the platinum sample. The dynamic light scattering experiment revealed an average hydrodynamic diameter of 353.6 nm for the PEGylated Pt NPs. The cytotoxicity profile of PEGylated Pt NPs was assessed on a normal cell line (L929) and a breast cancer cell line (MCF-7) using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. The results revealed an IC50of 79.18 μg ml-1on the cancer cell line and non-toxic behaviour on the normal cell line. In the dual staining apoptosis assay, it was observed that the mortality of cells cultured in conjunction with platinum nanoparticles intensified and the proliferative activity of MCF-7 cells gradually diminished over time in correlation with the increasing concentration of the PEGylated Pt NPs sample. Thein vitroDCFH-DA assay for oxidative stress assessment in nanoparticle-treated cells unveiled the mechanistic background of the anticancer activity of PEGylated platinum nanoparticles as ROS-assisted mitochondrial dysfunction.

Hexagonal Boron Nitride Quantum Dots Embedded on Layer-by-Layer Films for Peroxidase-Assisted Colorimetric Detection of β-Galactosidase Producing Pathogens

Pathogen detection has become a major research area all over the world for water quality surveillance and microbial risk assessment. Therefore, designing simple and sensitive detection kits plays a key role in envisaging and evaluating the risk of disease outbreaks and providing quality healthcare settings. Herein, we have designed a facile and low-cost colorimetric sensing strategy for the selective and sensitive determination of β-galactosidase producing pathogens. The hexagonal boron nitride quantum dots (h-BN QDs) were established as a nanozyme that showed prominent peroxidase-like activity, which catalyzes 3,3',5,5'-tetramethylbenzidine (TMB) oxidation by H2O2. The h-BN QDs were embedded on a layer-by-layer assembled agarose biopolymer. The β-galactosidase enzyme partially degrades β-1,4 glycosidic bonds of agarose polymer, resulting in accessibility of h-BN QDs on the solid surface. This assay can be conveniently conducted and analyzed by monitoring the blue color formation due to TMB oxidation within 30 min. The nanocomposite was stable for more than 90 days and was showing TMB oxidation after incubating it with Escherichia coli (E. coli). The limit of detection was calculated to be 1.8 × 106 and 1.5 × 106 CFU/mL for E. coli and Klebsiella pneumonia (K. pneumonia), respectively. Furthermore, this novel sensing approach is an attractive platform that was successfully applied to detect E. coli in spiked water samples and other food products with good accuracy, indicating its practical applicability for the detection of pathogens in real samples.

Recent trends in targeted delivery of smart nanocarrier-based microbial enzymes for therapeutic applications

Smart carrier-based immobilization has widened the use of enzymes for the treatment of several disorders. Large surface areas, tunable morphology, and surface modification ability aid the targeted and controlled release of therapeutic enzymes from such formulations. Smart nanocarriers, such as polymeric carriers, liposomes, and silica have also increased the stability, half-life, and permeability of these enzymes. In this review, summarize recent advances in the smart immobilization of microbial enzymes and their development as precision nanomedicine for the treatment of cancer, thrombosis, phenylketonuria (PKU), and wound healing. We also discuss the challenges and measures to be adopted for the successful clinical translation of these formulations.

Sensing of heavy metal Pb2+ ions in water utilizing the photonic structure of highly controlled hexagonal TiON/TiO2 nanotubes

The detection of heavy metals in water, especially Pb2+ ions, is important due to their severe hazardous effects. To address this issue, a highly controlled hexagonal TiON/TiO2 heterostructure has been synthesized in this study. The fabrication process involved the utilization of atomic layer deposition and direct current sputtering techniques to deposit TiO2 and TiON layers onto a porous Al2O3 membrane used as a template. The resulting heterostructure exhibits a well-ordered hollow tube structure with a diameter of 345 nm and a length of 1.2 µm. The electrochemical sensing of Pb2+ ions in water is carried out using a cyclic voltammetry technique under both light and dark conditions. The concentration range for the Pb2+ ions ranges from 10-5 to 10-1 M. The sensitivity values obtained for the sensor are 1.0 × 10-6 in dark conditions and 1.0 × 10-4 in light conditions. The remarkable enhancement in sensitivity under light illumination can be attributed to the increased activity and electron transfer facilitated by the presence of light. The sensor demonstrates excellent reproducibility, highlighting its reliability and consistency. These findings suggest that the proposed sensor holds great promise for the detection of Pb2+ ions in water, thereby facilitating environmental monitoring, water quality assessment, and safety regulation across various industries. Furthermore, the eco-friendly and straightforward preparation techniques employed in its fabrication provide a significant advantage for practical and scalable implementation.

Biomedical,clinical and environmental applications of platinum-based nanohybrids: An updated review

Platinum nanoparticles (Pt NPs) have numerous applications in various sectors, including pharmacology, nanomedicine, cancer therapy, radiotherapy, biotechnology and environment mitigation like removal of toxic metals from wastewater, photocatalytic degradation of toxic compounds, adsorption, and water splitting. The multifaceted applications of Pt NPs because of their ultra-fine structures, large surface area, tuned porosity, coordination-binding, and excellent physiochemical properties. The various types of nanohybrids (NHs) of Pt NPs can be fabricated by doping with different metal/metal oxide/polymer-based materials. There are several methods to synthesize platinum-based NHs, but biological processes are admirable because of green, economical, sustainable, and non-toxic. Due to the robust physicochemical and biological characteristics of platinum NPs, they are widely employed as nanocatalyst, antioxidant, antipathogenic, and anticancer agents. Indeed, Pt-based NHs are the subject of keen interest and substantial research area for biomedical and clinical applications. Hence, this review systematically studies antimicrobial, biological, and environmental applications of platinum and platinum-based NHs, predominantly for treating cancer and photo-thermal therapy. Applications of Pt NPs in nanomedicine and nano-diagnosis are also highlighted. Pt NPs-related nanotoxicity and the potential and opportunity for future nano-therapeutics based on Pt NPs are also discussed.

Biosynthesis of Nanoparticles from Various Biological Sources and Its Biomedical Applications

In the last few decades, the broad scope of nanomedicine has played an important role in the global healthcare industry. Biological acquisition methods to obtain nanoparticles (NPs) offer a low-cost, non-toxic, and environmentally friendly approach. This review shows recent data about several methods for procuring nanoparticles and an exhaustive elucidation of biological agents such as plants, algae, bacteria, fungi, actinomycete, and yeast. When compared to the physical, chemical, and biological approaches for obtaining nanoparticles, the biological approach has significant advantages such as non-toxicity and environmental friendliness, which support their significant use in therapeutic applications. The bio-mediated, procured nanoparticles not only help researchers but also manipulate particles to provide health and safety. In addition, we examined the significant biomedical applications of nanoparticles, such as antibacterial, antifungal, antiviral, anti-inflammatory, antidiabetic, antioxidant, and other medical applications. This review highlights the findings of current research on the bio-mediated acquisition of novel NPs and scrutinizes the various methods proposed to describe them. The bio-mediated synthesis of NPs from plant extracts has several advantages, including bioavailability, environmental friendliness, and low cost. Researchers have sequenced the analysis of the biochemical mechanisms and enzyme reactions of bio-mediated acquisition as well as the determination of the bioactive compounds mediated by nanoparticle acquisition. This review is primarily concerned with collating research from researchers from a variety of disciplines that frequently provides new clarifications to serious problems.

An ultra-light sustainable sponge for elimination of microplastics and nanoplastics

The currently established tools and materials for elimination of the emerging contaminants from environmental and food matrices, particularly micro- and nano-scale plastics, have been largely limited by complicated preparation/operation, high cost, and poor degradability. Here we show that, crosslinking naturally occurring corn starch and gelatin produces ultralight porous sponge upon freeze-drying that can be readily enzymatically decomposed to glucose; The sponge affords capture of micro- and nano-scale plastics into its pores by simple pressing in an efficiency up to 90% while preserving excellent mechanical strength. Heterogeneous diffusion was found to play a dominant role in the adsorption of microplastics by the starch-gelatin sponge. Investigations into the performance of the sponge in complex matrices including tap water, sea water, soil surfactant, and take-out dish soup, further reveal a considerably high removal efficiency (60%∼70%) for the microplastics in the real samples. It is also suggested tiny plastics in different sizes be removable using the sponge with controlled pore size. With combined merits of sustainability, cost-effectiveness, and simple operation without the need for professional background for this approach, industrial and even household removal of tiny plastic contaminants from environmental and food samples are within reach.

Synthesis, characterization, and antibacterial activities of a heteroscorpionate derivative platinum complex against methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is one of the species with the greatest clinical importance and greatest impact on public health. In fact, methicillin-resistant S. aureus (MRSA) is considered a pandemic pathogen, being essential to develop effective medicines and combat its rapid spread. This study aimed to foster the translation of clinical research outcomes based on metallodrugs into clinical practice for the treatment of MRSA. Bearing in mind the promising anti-Gram-positive effect of the heteroscorpionate ligand 1,1’-(2-(4-isopropylphenyl)ethane-1,1-diyl)bis(3,5-dimethyl-1H-pyrazole) (2P), we propose the coordination of this compound to platinum as a clinical strategy with the ultimate aim of overcoming resistance in the treatment of MRSA. Therefore, the novel metallodrug 2P-Pt were synthetized, fully characterized and its antibacterial effect against the planktonic and biofilm state of S. aureus evaluated. In this sense, three different strains of S. aureus were studied, one collection strain of S. aureus sensitive to methicillin and two clinical MRSA strains. To appraise the antibacterial activity, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), minimum biofilm inhibitory concentration (MBIC), and minimum biofilm eradication concentration (MBEC) were determined. Moreover, successful outcomes on the development of biofilm in a wound-like medium were obtained. The mechanism of action for 2P-Pt was proposed by measuring the MIC and MBC with EDTA (cation mediated mechanism) and DMSO (exogenous oxidative stress mechanism). Moreover, to shed light on the plausible antistaphylococcal mechanism of this novel platinum agent, additional experiments using transmission electron microscopy were carried out. 2P-Pt inhibited the growth and eradicated the three strains evaluated in the planktonic state. Another point worth stressing is the inhibition in the growth of MRSA biofilm even in a wounded medium. The results of this work support this novel agent as a promising therapeutic alternative for preventing infections caused by MRSA.

Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method. Their physicochemical and X-ray attenuation properties were characterized. All polymer-coated Pt-NPs had an average particle diameter (davg) of 2.0 nm. Polymers grafted onto Pt-NP surfaces exhibited excellent colloidal stability (i.e., no precipitation after synthesis for >1.5 years) and low cellular toxicity. The X-ray attenuation power of the polymer-coated Pt-NPs in aqueous media was stronger than that of the commercial iodine contrast agent Ultravist at the same atomic concentration and considerably stronger at the same number density, confirming their potential as computed tomography contrast agents.

Smart delivery systems for microbial biofilm therapy: Dissecting design, drug release and toxicological features

Bacterial biofilms are highly protected surface attached communities of bacteria that typically cause chronic infections. To address their recalcitrance to antibiotics and minimise side effects of current therapies, smart drug carriers are being explored as promising platforms for antimicrobials. Herein, we briefly summarize recent efforts and considerations that have been applied in the design of these smart carriers. We guide readers on a journey on how they can leverage the inherent biofilm microenvironment, external stimuli, or combine both types of stimuli in a predictable manner. The specific carrier features that are responsible for their 'on-demand' properties are detailed and their impact on antibiofilm property are further discussed. Moreover, an analysis on the impact of such features on drug release profiles is provided. Since nanotechnology represents a significant slice of the drug delivery pie, some insights on the potential toxicity are also depicted. We hope that this review inspires researchers to use their knowledge and creativity to design responsive systems that can eradicate biofilm infections.

A MALDI-MS-based impact assessment of ZnO nanoparticles, nanorods and quantum dots on the lipid profile of bacterial pathogens

MALDI-MS was used for studying the impact of zinc oxide (ZnO) nanomaterials on Pseudomonas aeruginosa and Staphylococcus aureus. The growth patterns of both these bacterial pathogens in the presence of the ZnO nanomaterials and the subsequent lipidomic changes were assessed using an optimized simple, rapid MALDI-MS based methodology. All three nanostructures tested exhibited differential bactericidal activity unique to P. aeruginosa and S. aureus. The results indicated that the ZnO nanomaterials were highly inhibitory to S. aureus even at 70 mg L^-1, while in the case of P. aeruginosa, the ZnO nanomaterials were compatible for up to 10 h and beyond 10 h only marginal growth inhibition was observed. The results proved that the shapes of the ZnO nanomaterials did not affect their toxicity properties. MALDI-MS was applied to study the lipidomic changes of P. aeruginosa and S. aureus after nanomaterial treatment, in order to throw light on the mechanism of growth inhibition. The results from the MALDI-MS studies showed that the ZnO nanostructures exhibited only marginal changes in the lipidomic profile both in the case of P. aeruginosa and S. aureus. These preliminary results indicate that the mechanism of growth inhibition by the ZnO nanomaterial is not through lipid-based interactions, but apparently more so via protein inhibitions.

Inorganic Nanoflowers—Synthetic Strategies and Physicochemical Properties for Biomedical Applications: A Review

Nanoflowers, which are flower-shaped nanomaterials, have attracted significant attention from scientists due to their unique morphologies, facile synthetic methods, and physicochemical properties such as a high surface-to-volume ratio, enhanced charge transfer and carrier immobility, and an increased surface reaction efficiency. Nanoflowers can be synthesized using inorganic or organic materials, or a combination of both (called a hybrid), and are mainly used for biomedical applications. Thus far, researchers have focused on hybrid nanoflowers and only a few studies on inorganic nanoflowers have been reported. For the first time in the literature, we have consolidated all the reports on the biomedical applications of inorganic nanoflowers in this review. Herein, we review some important inorganic nanoflowers, which have applications in antibacterial treatment, wound healing, combinatorial cancer therapy, drug delivery, and biosensors to detect diseased conditions such as diabetes, amyloidosis, and hydrogen peroxide poisoning. In addition, we discuss the recent advances in their biomedical applications and preparation methods. Finally, we provide a perspective on the current trends and potential future directions in nanoflower research. The development of inorganic nanoflowers for biomedical applications has been limited to date. Therefore, a diverse range of nanoflowers comprising inorganic elements and materials with composite structures must be synthesized using ecofriendly synthetic strategies.

Functionalized Platinum Nanoparticles with Biomedical Applications

Functionalized platinum nanoparticles have been of considerable interest in recent research due to their properties and applications, among which they stand out as therapeutic agents. The functionalization of the surfaces of nanoparticles can overcome the limits of medicine by increasing selectivity and thereby reducing the side effects of conventional drugs. With the constant development of nanotechnology in the biomedical field, functionalized platinum nanoparticles have been used to diagnose and treat diseases such as cancer and infections caused by pathogens. This review reports on physical, chemical, and biological methods of obtaining platinum nanoparticles and the advantages and disadvantages of their synthesis. Additionally, applications in the biomedical field that can be utilized once the surfaces of nanoparticles have been functionalized with different bioactive molecules are discussed, among which antibodies, biodegradable polymers, and biomolecules stand out.

Nanomaterials enabling clinical translation of antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (aPDT) has emerged as a promising approach to aid the fight against looming antibiotic resistance. aPDT harnesses the energy of light through photosenstizers to generate highly reactive oxygen species that can inactivate bacteria and fungi with no resistance. To date aPDT has shown great efficacy against microbes causing localized infections in the skin and the oral cavity. However, its wide application in clinical settings has been limited due to both physicochemical and biological challenges. Over the past decade nanomaterials have contributed to promoting photosensitizer performance and aPDT efficiency, yet further developments are required to establish accredited treatment options. In this review we discuss the challenges facing the clinical application of aPDT and the opportunities that nanotechnology may offer to promote the safety and efficiency of aPDT.

Green Metallic Nanoparticles: Biosynthesis to Applications

Current advancements in nanotechnology and nanoscience have resulted in new nanomaterials, which may pose health and environmental risks. Furthermore, several researchers are working to optimize ecologically friendly procedures for creating metal and metal oxide nanoparticles. The primary goal is to decrease the adverse effects of synthetic processes, their accompanying chemicals, and the resulting complexes. Utilizing various biomaterials for nanoparticle preparation is a beneficial approach in green nanotechnology. Furthermore, using the biological qualities of nature through a variety of activities is an excellent way to achieve this goal. Algae, plants, bacteria, and fungus have been employed to make energy-efficient, low-cost, and nontoxic metallic nanoparticles in the last few decades. Despite the environmental advantages of using green chemistry-based biological synthesis over traditional methods as discussed in this article, there are some unresolved issues such as particle size and shape consistency, reproducibility of the synthesis process, and understanding of the mechanisms involved in producing metallic nanoparticles via biological entities. Consequently, there is a need for further research to analyze and comprehend the real biological synthesis-dependent processes. This is currently an untapped hot research topic that required more investment to properly leverage the green manufacturing of metallic nanoparticles through living entities. The review covers such green methods of synthesizing nanoparticles and their utilization in the scientific world.

Basic physiology of Pseudomonas aeruginosa contacted with carbon nanocomposites

Experiments describing properties of nanomaterials on bacteria are frequently limited to the disk diffusion method or other end-point methods indicating viability or survival rate in plate count assay. Such experimental design does not show the dynamic changes in bacterial physiology, mainly when performed on reference microorganisms (Escherichia coli and Staphylococcus aureus). Testing other microorganisms, such as Pseudomonas aeruginosa, could provide novel insights into the microbial response to nanomaterials. Therefore, we aimed to test selected carbon nanomaterials and their components in a series of experiments describing the basic physiology of P. aeruginosa. Concentrations ranging from 15.625 to 1000 µg/mL were tested. The optical density of cultures, pigment production, respiration, growth curve analysis, and biofilming were tested. The results confirmed variability in the response of P. aeruginosa to tested nanostructures, depending on their concentration. The co-incubation with the nanostructures (in concentration 125 µg/mL) could inhibit the population growth (in most cases) or promote it in the case of graphene oxide. Furthermore, a specific concentration of a given nanomaterial could cause contradictory effects leading to stimulation or inhibition of pigmentation, an optical density of the cultures, or biofilm formation. We have found that particularly nanomaterials containing TiO2 could induce pigmentation in P. aeruginosa, which indicates the possibility of increased virulence. On the other hand, nanocomposites containing cobalt nanoparticles had the highest anti-bacterial potential when cobalt was displayed on the surface. Our approach revealed changes in respiration and growth dynamics that can be used to search for nanomaterials’ application in biotechnology.

Role of nanomaterials in deactivating multiple drug resistance efflux pumps - A review

The changes in lifestyle and living conditions have affected not only humans but also microorganisms. As man invents new drugs and therapies, pathogens alter themselves to survive and thrive. Multiple drug resistance (MDR) is the talk of the town for decades now. Many generations of medications have been termed useless as MDR rises among the infectious population. The surge in nanotechnology has brought a new hope in reducing this aspect of resistance in pathogens. It has been observed in several laboratory-based studies that the use of nanoparticles had a synergistic effect on the antibiotic being administered to the pathogen; several resistant strains scummed to the stress created by the nanoparticles and became susceptible to the drug. The major cause of resistance to date is the efflux system, which makes the latest generation of antibiotics ineffective without reaching the target site. If species-specific nanomaterials are used to control the activity of efflux pumps, it could revolutionize the field of medicine and make the previous generation resistant medications active once again. Therefore, the current study was devised to assess and review nanoparticles' role on efflux systems and discuss how specialized particles can be designed towards an infectious host's particular drug ejection systems.

Biocompatible Core–Shell-Structured Si-Based NiO Nanoflowers and Their Anticancer Activity

Compared to most of nano-sized particles, core–shell-structured nanoflowers have received great attention as bioactive materials because of their high surface area with the flower-like structures. In this study, core–shell-structured Si-based NiO nanoflowers, Si@NiO, were prepared by a modified chemical bath deposition method followed by thermal reduction. The crystal morphology and basic structure of the composites were characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) and porosity analysis (BJT), and inductively coupled plasma optical emission spectrometry (ICP-OES). The electrochemical properties of the Si@NiO nanoflowers were examined through the redox reaction of ascorbic acid with the metal ions present on the surface of the core–shell nanoflowers. This reaction favored the formation of reactive oxygen species. The Si@NiO nanoflowers showed excellent anticancer activity and low cytotoxicity toward the human breast cancer cell line (MCF-7) and mouse embryonic fibroblasts (MEFs), respectively, demonstrating that the anticancer activities of the Si@NiO nanoflowers were primarily derived from the oxidative capacity of the metal ions on the surface, rather than from the released metal ions. Thus, this proves that Si-based NiO nanoflowers can act as a promising candidate for therapeutic applications.

Biosynthesis and characterization of platinum nanoparticles using Iraqi Zahidi dates and evaluation of their biological applications

Platinum nanoparticles (Pt NPs) were synthesized by utilizing the Zahidi dates extract by green synthesis technique. Platinum salts were successfully reduced to their corresponding Pt NPs in the presence of aqueous dates extract which considers a rich source of phytochemicals that led to the reduction of Pt+4 to Pt° atoms by providing electrons for these ions. Many techniques characterized the nanoparticles. TEM analysis showed that the Pt NPs were exhibited in diameters ranging from (30-45) nm. FE-SEM images display nanoparticles in spherical shapes. AFM screening shows that Platinum nanoparticles had small size distribution. XRD diffraction examination showed that the formation of Platinum nanoparticles exhibits a face centred cubic crystalline structure by spectrum comparative to the standard confirmed spectrum of Platinum particles produced in the experiments were in the shape of nanocrystals. The fourier transform infrared spectroscopy spectrum showed various peaks ranging from (400-4000) cm-1 used to identify the functional groups responsible for reducing and capping of Pt NPs. Cancer cells including the ovarian cancer SKO-3 cell line and Oesophageal cancer SK-GT-4 cell line were exposed to a series of prepared Platinum nanoparticle concentrations (0.00125, 0.0025, 0.005, 0.01) M, and the inhibition rate of growth in cells was measured for 72 h. The cytotoxicity screening showed that there was a highly toxic effect on the cancer cells. Gram-negative bacterial strain Pseudomonas aeruginosa and Gram-positive bacterial strain Streptococcus pyogenes were exposed to a series of concentrations from prepared Platinum nanoparticles (0.00125, 0.0025, 0.005, 0.01) M. The results exhibited significant inhibitory activity and the rate of bacterial growth inhibition increased with increasing concentration.

A mechanistic perspective on targeting bacterial drug resistance with nanoparticles

Bacterial infections are an important cause of mortality worldwide owing to the prevalence of drug resistant bacteria. Bacteria develop resistance against antimicrobial drugs by several mechanisms such as enzyme inactivation, reduced cell permeability, modifying target site or enzyme, enhanced efflux because of high expression of efflux pumps, biofilm formation or drug-resistance gene expression. New and alternative ways such as nanoparticle (NP) applications are being established to overcome the growing multidrug-resistance in bacteria. NPs have unique antimicrobial characteristics that make them appropriate for medical application to overcome antibiotic resistance. The proposed antibacterial mechanisms of NPs are cell membrane damage, changing cell wall penetration, reactive oxygen species (ROS) production, effect on DNA and proteins, and impact on biofilm formation. The present review mainly focuses on discussing various mechanisms of bacterial drug resistance and the applications of NPs as alternative antibacterial systems. Combination therapy of NPs and antibiotics as a novel approach in medicine towards antimicrobial resistance is also discussed.

Bacterial Surface Colonization of Sputter-Coated Platinum Films

Due to its biocompatibility and advantageous electrochemical properties, platinum is commonly used in the design of biomedical devices, e.g., surgical instruments, as well as electro-medical or orthopedic implants. This article verifies the hypothesis that a thin layer of sputter-coated platinum may possess antibacterial effects. The purpose of this research was to investigate the adhesion and growth ability of a model strain of Gram-negative bacteria, Escherichia coli, on a surface of a platinum-coated glass slide. Although some previous literature reports suggests that a thin layer of platinum would inhibit the formation of bacterial biofilm, the results of this study suggest otherwise. The decrease in the number of bacterial cells attached to the platinum-coated glass, which was observed within first three hours of culturing, was found to be a short-time effect, vanishing after 24 h. Consequently, it was shown that a thin layer of sputter-coated platinum did not exhibit any antibacterial effect. For this reason, this study indicates an urgent need for the development of new methods of surface modification that could reduce bacterial surface colonization of platinum-based biomedical devices.

Silver Nanoparticles as a Novel Potential Preventive Agent against Acanthamoeba Keratitis

Free living, cosmopolitan amoebae from Acanthamoeba genus present a serious risk to human health. As facultative human parasites, these amoebae may cause Acanthamoeba keratitis (AK). Acanthamoeba keratitis is a severe, vision-threatening corneal infection with non-specific symptoms. The number of reported AK cases worldwide has been increasing every year. Moreover, 90% of Acanthamoeba keratitis cases are related to contact lens use. Wearing and storage contact lenses not in accordance with the physicians and manufacturers recommendations are the primary key risk factors of this disease. Amoebae can easily adhere to the contact lens surface and transmit to the corneal epithelium. Preventing amoebae adhesion to the contact lens surface could significantly decrease the number of AK infections. Until now, the effective therapy against AK is still under development. Currently proposed therapies are mainly limited to the chlorhexidine digluconate combined with propamidine isethionate or hexamidine applications, which are insufficient and very toxic to the eye. Due to lack of effective treatment, looking for new potential preventive agents is crucial to decrease the number of Acanthamoeba keratitis infections, especially among contact lens users. Nanoparticles have been already included in several novel therapies against bacteria, viruses, fungi, and protist. However, their anti-amoebic potential has not been fully tested yet. The aim of this study was to assess silver nanoparticles (AgNPs) and platinum nanoparticles (PtNPs) anti-amoebic activity and influence on the amoebae adhesion to the surface of four different groups of contact lenses-classified according to the Food and Drugs Administration (FDA) guidelines. The obtained results show that both tested nanoparticles were effective against Acanthamoeba trophozoites and decreased the amoebae adhesion to the contact lens surface. AgNPs showed better anti-amoebic activity to cytotoxicity dependence and reduced amoebae adhesion in a wider spectrum of the tested contact lenses. Our studies also confirmed that ionization next to hydration of the contact lens material is a crucial parameter influencing the Acanthamoeba adhesion to the contact lens surface. In conclusion, silver nanoparticles might be considered as a novel preventive agent against Acanthamoeba keratitis infection.

Adaptive changes induced by noble-metal nanostructures in vitro and in vivo

The unique features of noble-metal nanostructures (NMNs) are leading to unprecedented expansion of research and exploration of their application in therapeutics, diagnostics and bioimaging fields. With the ever-growing applications of NMNs, both therapeutic and environmental NMNs are likely to be exposed to tissues and organs, requiring careful studies towards their biological effects in vitro and in vivo. Upon NMNs exposure, tissues and cells may undergo a series of adaptive changes both in morphology and function. At the cellular level, the accumulation of NMNs in various subcellular organelles including lysosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, and nucleus may interfere with their functions, causing changes in a variety of cellular functions, such as digestion, protein synthesis and secretion, energy metabolism, mitochondrial respiration, and proliferation. In animals, retention of NMNs in metabolic-, respiratory-, immune-related, and other organs can trigger significant physiological and pathological changes to these organs and influence their functions. Exploring how NMNs interact with tissues and cells and the underlying mechanisms are of vital importance for their future applications. Here, we illustrate the characteristics of NMNs-induced adaptive changes both in vitro and in vivo. Potential strategies in the design of NMNs are also discussed to take advantage of beneficial adaptive changes and avoid unfavorable changes for the proper implementation of these nanoplatforms.

A Comprehensive Review on the Synthesis, Characterization, and Biomedical Application of Platinum Nanoparticles

Platinum nanoparticles (PtNPs) are noteworthy scientific tools that are being explored in various biotechnological, nanomedicinal, and pharmacological fields. They are unique because of their large surface area and their numerous catalytic applications such as their use in automotive catalytic converters and as petrochemical cracking catalysts. PtNPs have been widely utilized not only in the industry, but also in medicine and diagnostics. PtNPs are extensively studied because of their antimicrobial, antioxidant, and anticancer properties. So far, only one review has been dedicated to the application of PtNPs to nanomedicine. However, no studies describe the synthesis, characterization, and biomedical application of PtNPs. Therefore, the aim of this review is to provide a comprehensive assessment of the current knowledge regarding the synthesis, including physical, chemical, and biological and toxicological effects of PtNPs on human health, in terms of both in vivo and in vitro experimental analysis. Special attention has been focused on the biological synthesis of PtNPs using various templates as reducing and stabilizing agents. Finally, we discuss the biomedical and other applications of PtNPs.

Improved delivery of doxorubicin using rationally designed PEGylated platinum nanoparticles for the treatment of melanoma

Efficient delivery of chemotherapeutic drugs to tumor cells is one of the crucial issues for modern day cancer therapy. In this article, we report the synthesis of poly ethylene glycol (PEG) assisted colloidal platinum nanoparticles (PtNPs) by borohydride reduction method at room temperature. PtNPs are stable at room temperature for more than 2 years and are stable in serum and phosphate buffer (pH = 7.4) solution for one week. PtNPs show biocompatibility in different normal cell lines (in vitro) and chicken egg embryonic model (ex vivo). Further, we designed and fabricated PtNPs-based drug delivery systems (DDS: PtNPs-DOX) using doxorubicin (DOX), a FDA approved anticancer drug. Various analytical techniques were applied to characterize the nanomaterials (PtNPs) and DDS (PtNPs-DOX). This DDS exhibits inhibition of cancer cell (B16F10 and A549) proliferation, observed by different in vitro assays. PtNPs-DOX induces apoptosis in cancer cells observed by annexin-V staining method. Intraperitoneal (IP) administration of PtNPs-DOX shows substantial reduction of tumor growth in subcutaneous murine melanoma tumor model compared to control group with free drug. Up-regulation of tumor suppressor protein p53 and down regulation of SOX2 and Ki-67 proliferation markers in melanoma tumor tissues (as observed by immunofluorescence and western blot analysis) indicates probable molecular mechanism for the anticancer activity of DDS. Considering the in vitro and pre-clinical (in vivo) results in murine melanoma, it is believed that platinum nanoparticle-based drug delivery formulation could be exploited to develop an alternative therapeutic nanomedicine for cancer therapy in the near future.

Recent Advances in Nanozyme Research

As a new generation of artificial enzymes, nanozymes have the advantages of high catalytic activity, good stability, low cost, and other unique properties of nanomaterials. Due to their wide range of potential applications, they have become an emerging field bridging nanotechnology and biology, attracting researchers in various fields to design and synthesize highly catalytically active nanozymes. However, the thorough understanding of experimental phenomena and the mechanisms beneath practical applications of nanozymes limits their rapid development. Herein, the progress of experimental and computational research of nanozymes on two issues over the past decade is briefly reviewed: (1) experimental development of new nanozymes mimicking different types of enzymes. This covers their structures and applications ranging from biosensing and bioimaging to therapeutics and environmental protection. (2) The catalytic mechanism proposed by experimental and theoretical study. The challenges and future directions of computational research in this field are also discussed.

Organic resolution function and effects of platinum nanoparticles on bacteria and organic matter

Rapid progress has been made in terms of metal nanoparticles studied in numerous fields. Metal nanoparticles have also been used in medical research, and antibacterial properties and anticancer effects have been reported. However, the underlying mechanism responsible for these effects has not been fully elucidated. Therefore, the present study focused on platinum nanoparticles (PtNPs) and examined their antibacterial properties and functional potential for decomposing organic matter, considering potential applications in the dental field. PtNPs were allowed to react with dental-related bacteria (Streptococcus mutans; Enterococcus faecalis, caries; Porphyromonas gingivalis, and endodontic and periodontal lesions). Antibacterial properties were evaluated by measuring colony formation. In addition, PtNPs were allowed to react with albumin and lipopolysaccharides (LPSs), and the functional potential to decompose organic matter was evaluated. All evaluations were performed in vitro. Colony formation in all bacterial species was completely suppressed by PtNPs at concentrations of >5 ppm. The addition of PtNPs at concentrations of >10 ppm significantly increased fragmentation and decomposition. The addition of PtNPs at concentrations of >125 pico/mL to 1 EU/mL LPS resulted in significant amounts of decomposition and elimination. The results revealed that PtNPs had antibacterial effects against dental-related bacteria and proteolytic potential to decompose proteins and LPS, an inflammatory factor associated with periodontal disease. Therefore, the use and application of PtNPs in periodontal and endodontic treatment is considered promising.

Autophagy is a new protective mechanism against the cytotoxicity of platinum nanoparticles in human trophoblasts

Nanoparticles are widely used in commodities, and pregnant women are inevitably exposed to these particles. The placenta protects the growing fetus from foreign or toxic materials, and provides energy and oxygen. Here we report that autophagy, a cellular mechanism to maintain homeostasis, engulfs platinum nanoparticles (nPt) to reduce their cytotoxicity in trophoblasts. Autophagy was activated by nPt in extravillous trophoblast (EVT) cell lines, and EVT functions, such as invasion and vascular remodeling, and proliferation were inhibited by nPt. These inhibitory effects by nPt were augmented in autophagy-deficient cells. Regarding the dynamic state of nPt, analysis using ICP-MS demonstrated a higher accumulation of nPt in the autophagosome-rich than the cytoplasmic fraction in autophagy-normal cells. Meanwhile, there were more nPt in the nuclei of autophagy-deficient cells, resulting in greater DNA damage at a lower concentration of nPt. Thus, we found a new protective mechanism against the cytotoxicity of nPt in human trophoblasts.

Interactions of newly synthesized platinum nanoparticles with ICR-191 and their potential application

One of the greatest challenges of modern medicine is to find cheaper and easier ways to produce transporters for biologically active substances, which will provide selective and efficient drug delivery to the target cells, while causing low toxicity towards healthy cells. Currently, metal-based nanoparticles are considered a successful and viable solution to this problem. In this work, we propose the use of novel synthesis method of platinum nanoparticles (PtNPs) connected with their precise biophysical characterization and assessment of their potential toxicity. To work as an efficient nanodelivery platform, nanoparticles should interact with the desired active compounds spontaneously and non-covalently. We investigated possible direct interactions of PtNPs with ICR-191, a model acridine mutagen with well-established biophysical properties and mutagenic activity, by Dynamic Light Scattering, fluorescence spectroscopy, and Isothermal Titration Calorimetry. Moreover, to determine the biological activity of ICR-191-PtNPs aggregates, we employed Ames mutagenicity test, eukaryotic cell line analysis and toxicity test against the model organism Caenorhabditis elegans. PtNPs' interesting physicochemical properties associated to the lack of toxicity in a tested range of concentrations, as well as their ability to modulate ICR-191 biological activity, suggest that these particles successfully work as potential delivery platforms for different biologically active substances.

A perspective on biogenic synthesis of platinum nanoparticles and their biomedical applications

In recent era, the interest on inorganic nanoparticles is augmenting due to their engrossing and uncanny properties. Among them, platinum nanoparticles (PtNPs) are highly remarkable owing to their intrinsic physicochemical and biological properties making them an effective candidate towards catalytic and biomedical applications. Nevertheless, conventional physical and chemical methodologies of PtNPs synthesis are among the most prevalent protocols to synthesize PtNPs of desired shape and size. However, the above methods create notable concern to health and environment due to the use of harsh and toxic chemicals as well as violent reaction conditions. Hence, an economic, eco-friendly, non-toxic and sustainable route for the synthesis of PtNPs is the need of the hour to circumvent the shortcomings associated with conventional methodologies. In this aspect, the approach of green synthesis has lightened up the way for the environmentally benign synthesis of PtNPs. Interestingly, this review focuses chiefly on the green synthesis of PtNPs from various biological entities such as microorganisms, plants, seaweeds and other innovative miscellaneous protocols. Furthermore, it also summarizes the potential biomedical applications of PtNPs especially as an antibacterial agent and their role as nanomedicine. Overall, the emerging biogenic synthesis of PtNPs makes it feasible to foresee more promising biomedical outcomes in the upcoming future.

Evaluation of colloidal platinum on cytotoxicity, oxidative stress and barrier permeability across the gut epithelium

Colloidal platinum (Pt) is widely consumed due to its health promoting benefits. However, the exact biological effects of these nanoparticles have not been studied in detail, particularly in the gut. In the present study we observed that colloidal Pt was not cytotoxic towards three different epithelial colon cancer cell lines. Co-treatment of the colon cancer cell line Caco-2 with the oxidative stress inducing agent hydrogen peroxide (H2O2) and colloidal Pt resulted in a significant decrease in H2O2 induced oxidative stress. Colloidal Pt by itself did not induce any oxidative stress. Additionally, both overnight pretreatment of Caco-2 cells with colloidal Pt followed by 1 h treatment with H2O2, or co-treatment of cells for 1 h with colloidal Pt and H2O2 resulted in a significant recovery of cell death. Of note, the same protective effects of colloidal Pt were not observed when the oxidative stress was induced in the presence of 2, 2-azobis (2-amidinopropane) dihydrochloride, indicating that the source of free radicals may define the outcome of anti-oxidant activity of colloidal Pt. Colloidal Pt was also able to cross a model intestinal barrier formed in vitro with differentiated Caco-2 cells easily. Overall, our data indicate that colloidal Pt was not toxic towards intestinal epithelial cells, reduced H2O2 induced oxidative stress, protected from oxidative stress related death of intestinal epithelial cells and could pass a model gut barrier easily. Colloidal Pt can therefore be consumed orally for its anti-oxidant and other health promoting benefits.

Development of methanogens within cathodic biofilm in the single-chamber microbial electrolysis cell

The aim of this study was to investigate the development of cathodic biofilm and its effect on methane production in a single-chamber microbial electrolysis cell (MEC). The MEC with 1 g/L acetate was successfully operated within 31 cycles (∼2400 h). The maximum methane production rate and average current capture efficiency in the MEC reached 93 L/m³·d and 82%, respectively. Distinct stratification of Methanobacteriaceae within cathodic biofilm was observed after 9 cycles of operation. The relative abundance of Methanobacteriaceae in the microbial community increased from 45.3% (0-15 μm), 57.6% (15-30 μm), 66.9% (30-45 μm) to 77.2% (45-60 μm) within the cathodic biofilm. The methane production rates were positively correlated with the mcrA gene copy numbers in the cathodic biofilm. Our results should be useful to understand the mechanism of methane and hydrogen production in the MEC.

A repertoire of biomedical applications of noble metal nanoparticles

The emerging properties of noble metal nanoparticles are attracting huge interest from the translational scientific community. In this feature article, we highlight recent advances in the adaptation of noble metal nanomaterials and their biomedical applications in therapeutics, diagnostics and sensing.

Direct Analysis of Human Sputum for Differentiating Non-small Cell Lung Cancer by Neutral Desorption Extractive Electrospray Ionization Mass Spectrometry

Human sputum, a typical highly viscous biosample, was directly characterized at the molecular level using neutral desorption extractive electrospray ionization mass spectrometry (ND-EESI-MS) without multi-step sample pretreatment, in an attempt to provide a method for constructing the pattern recognition of rapid diagnosis of lung cancer. Under the optimal experiment conditions, glucose, amino acids, phosphoric lipids and other typical analytes in the sputum sample could be used to conduct qualitative or quantitative (in arginine) analysis. More interestingly, the full scan mass spectra from 50 patients of non-small cell lung cancer, recording the mass spectral fingerprints of sputum samples, were differentiated from the control group (50 healthy individuals) through principal component analysis (PCA). These findings suggest that valuable molecular information concealed in human sputum could be easily revealed and applied for conducting qualitative or quantitative analysis by direct ND-EESI-MS analysis.

Platinum nanoparticles in nanobiomedicine

Oxidative stress-dependent inflammatory diseases represent a major concern for the population's health worldwide. Biocompatible nanomaterials with enzymatic properties could play a crucial role in the treatment of such pathologies. In this respect, platinum nanoparticles (PtNPs) are promising candidates, showing remarkable catalytic activity, able to reduce the intracellular reactive oxygen species (ROS) levels and impair the downstream pathways leading to inflammation. This review reports a critical overview of the growing evidence revealing the anti-inflammatory ability of PtNPs and their potential applications in nanomedicine. It provides a detailed description of the wide variety of synthetic methods recently developed, with particular attention to the aspects influencing biocompatibility. Special attention has been paid to the studies describing the toxicological profile of PtNPs with an attempt to draw critical conclusions. The emerging picture suggests that the material per se is not causing cytotoxicity, while other physicochemical features related to the synthesis and surface functionalization may play a crucial role in determining the observed impairment of cellular functions. The enzymatic activity of PtNPs is also summarized, analyzing their action against ROS produced by pathological conditions within the cells. In particular, we extensively discuss the potential of these properties in nanomedicine to down-regulate inflammatory pathways or to be employed as diagnostic tools with colorimetric readout. A brief overview of other biomedical applications of nanoplatinum is also presented.

Nanoflowers: the future trend of nanotechnology for multi-applications

Nanoflowers are a newly developed class of nanoparticles showing structure similar to flower and gaining much attention due to their simple method of preparation, high stability and enhance efficiency. This article focuses on advantages, disadvantages, method of synthesis, types and applications of nanoflowers with futuristic approaches. The applications of nanoflower include its use as a biosensor for quick and precise detection of conditions like diabetes, Parkinsonism, Alzheimer, food infection, etc. Nanoflowers have been revealed for site-specific action and controlled delivery of drugs. The extended applications of nanoflowers cover purification of enzyme, removal of dye and heavy metal from water, gas-sensing using nickel oxide. Recent investigation shows 3 D structure of nanoflowers for enhancing surface sensitivity using Raman spectroscopy. This nanoflower system will act as a smart material in the near future due to high surface-to-volume ratio and enhance adsorption efficiency on its petals.

Photothermal lysis of pathogenic bacteria by platinum nanodots decorated gold nanorods under near infrared irradiation

Photothermal lysis is an effective method for fast removal of pathogenic bacteria from bacterial contaminated environments and human body, irrespective of bacterial drug resistance. In the present work, a highly effective photothermal agent, Au@Pt nanorods (NRs), was prepared by modification of Pt nanodots with particle size of 5nm on the surface of Au NRs with a length of ca. 41nm and a width of ca. 13nm. The LSPR absorbance band of Au@Pt NRs could be tuned from 755 to 845nm by changing the Pt loading from 0.05 to 0.2, as compared to Au NRs. The photothermal conversion efficiency of Au@Pt NRs depended on the Pt loading, Au@Pt NRs concentration, and power density. Under NIR irradiation, the Au@Pt_0.1 NRs exhibited the highest efficiency in photothermal lysis of both gram-positive and gram-negative bacteria. The introduction of Pt nanodots on the surface of Au@Pt NRs not only enhanced their photothermal conversions but also enhanced their affinity to bacteria and significantly decreased their cytotoxicity. The photothermal lysis of bacteria over Au@Pt NRs caused the damage onto the cell walls of bacteria, implying that the killing of bacteria probably went through the thermal ablation mechanism.

Platinum nanoparticles induce damage to DNA and inhibit DNA replication

Sparsely tested group of platinum nanoparticles (PtNPs) may have a comparable effect as complex platinum compounds. The aim of this study was to observe the effect of PtNPs in in vitro amplification of DNA fragment of phage λ, on the bacterial cultures (Staphylococcus aureus), human foreskin fibroblasts and erythrocytes. In vitro synthesized PtNPs were characterized by dynamic light scattering (PtNPs size range 4.8-11.7 nm), zeta potential measurements (-15 mV at pH 7.4), X-ray fluorescence, UV/vis spectrophotometry and atomic absorption spectrometry. The PtNPs inhibited the DNA replication and affected the secondary structure of DNA at higher concentrations, which was confirmed by polymerase chain reaction, DNA sequencing and DNA denaturation experiments. Further, cisplatin (CisPt), as traditional chemotherapy agent, was used in all parallel experiments. Moreover, the encapsulation of PtNPs in liposomes (LipoPtNPs) caused an approximately 2.4x higher of DNA damage in comparison with CisPt, LipoCisPt and PtNPs. The encapsulation of PtNPs in liposomes also increased their antibacterial, cytostatic and cytotoxic effect, which was determined by the method of growth curves on S. aureus and HFF cells. In addition, both the bare and encapsulated PtNPs caused lower oxidative stress (determined by GSH/GSSG ratio) in the human erythrocytes compared to the bare and encapsulated CisPt. CisPt was used in all parallel experiments as traditional chemotherapy agent.