Pharmacological potential of bioactive engineered nanomaterials

Behavioral, biochemical, histopathological evaluation and gene expression of brain injury induced by nanoceria injected intranasal or intraperitoneal in mice

Background

Nanotechnology has shown a remarkable progress nevertheless, there is a growing concern about probable neurotoxic and neurodegenerative effects due to NPs exposure. Various toxicological and epidemiological studies reported that the brain is a main target for ultrafine particles. Brain inflammation is considered as a possible mechanism that can participate to neurotoxic and neurodegenerative effects. Whether nanoparticles (NPs) may produce neurotoxicity and promote neurodegenerative is largely unstudied. The present study was done to investigate whether intranasal and intra-peritoneal exposure to cerium oxide nanoparticles (CeO2NPs, nanoceria (NC)) could cause neurotoxicity and neurodegenerative changes in the brain tissue through conducting some behavioral tests, biochemical evaluation, histopathological examinations of brain hippocampus and gene expressions.

Method

Fifteen mice were separated into 3 equal groups. In group (I) "control group", mice were received distilled water orally and kept as a control group. Mice in the group (II) "NC I/P group" were injected i.p with cerium oxide nanoparticles at a dose of 40 mg/kg b.wt, twice weekly for 3 weeks. In group (III) "NC I/N group" mice were received nanoceria intranasally (40 mg/kg b.wt), twice weekly for 3 weeks.

Results

Exposure to nanceria resulted in oxidative damage in brain tissue, a significant increase in malondialdehyde (MDA) and acetylcholinestrase (AchE) levels, significant decrease in reduced glutathione (GSH) concentration, upregulation in the apoptosis-related genes (c-Jun: c-Jun N-terminal kinases (JNKs), c-Fos: Fos protooncogene, AP-1 transcription factor subunit, c-Myc: c-myelocytomatosis oncogene product or MYC protooncogene, bHLH transcription factor), locomotor and cognitive impairment in mice but the effect was more obvious when nanoceria adminstred intraperitoneally.

Conculsion

Nanoceria cause oxidative damage in brain tissue of mice when adminstred nanoceria intraperitoneally more than those received nanoceria intranasal.

Bioactivity of cerium dioxide nanoparticles as a function of size and surface features

Nano-dispersed cerium dioxide is promising for use in medicine due to its unique physicochemical properties, including low toxicity, the safety of in vivo usage, active participation in different redox processes occurring in living cells, and its regenerative potential, manifested in the ability of CeO2 to participate repeatedly in redox reactions. In this work, we examined the biological activity of cerium dioxide nanoparticles (CeO2 NPs) synthesized by precipitation in mixed water/alcohol solutions at a constant pH of 9. This synthesis method allowed controlling the size and Ce3+/Ce4+ proportion on the surface of NPs, changing the synthesis conditions and obtaining highly stable suspensions of "naked" CeO2 NPs. Changes in the surface properties upon contact of CeO2 NPs with protein-rich media, e.g., bovine serum albumin and DMEM cell culture medium supplemented with 10% fetal bovine serum, the characteristics of nanoparticle uptake by mouse aortic endothelial cells and the antioxidant activity of the nanoparticles of different sizes were investigated by various state-of-the-art analytical methods.

Radioprotective Potency of Nanoceria

Cancer presents a significant medical challenge that requires effective management. Current cancer treatment options, such as chemotherapy, targeted therapy, radiotherapy, and immunotherapy, have limitations in terms of their efficacy and the potential harm they can cause to normal tissues. In response, researchers have been focusing on developing adjuvants that can enhance tumor responses while minimizing damage to healthy tissues. Among the promising options, nanoceria (NC), a type of nanoparticle composed of cerium oxide, has garnered attention for its potential to improve various cancer treatment regimens. Nanoceria has demonstrated its ability to exhibit toxicity towards cancer cells, inhibit invasion, and sensitize cancer cells to both radiation therapy and chemotherapy. The remarkable aspect is that nanoceria show minimal toxicity to normal tissues while protecting against various forms of reactive oxygen species generation. Its capability to enhance the sensitivity of cancer cells to chemotherapy and radiotherapy has also been observed. This paper thoroughly reviews the current literature on nanoceria's applications within different cancer treatment modalities, with a specific focus on radiotherapy. The emphasis is on nanoceria's unique role in enhancing tumor radiosensitization and safeguarding normal tissues from radiation damage.

MgO Nanoparticles Obtained from an Innovative and Sustainable Route and Their Applications in Cancer Therapy

This paper aimed to evaluate the biological damages towards diseased cells caused by the use of MgO nanoparticles (NPs). The NPs are produced by a calcination process of a precursor, which is an aqueous suspension of nanostructured Mg(OH)2, in turn synthesized following our original, time-energy saving and scalable method able to guarantee short times, high yield of production (up to almost 10 kg/week of NPs), low environmental impact and low energy demand. The MgO NPs, in the form of dry powders, are organized as a network of intercrystallite channels, in turn constituted by monodispersed and roughly spherical NPs < 10 nm, preserving the original pseudo hexagonal-platelet morphology of the precursor. The produced MgO powders are diluted in a PBS solution to obtain different MgO suspension concentrations that are subsequently put in contact, for 3 days, with melanoma and healthy cells. The viable count, made at 24, 48 and 72 h from the beginning of the test, reveals a good cytotoxic activity of the NPs, already at low MgO concentrations. This is particularly marked after 72 h, showing a clear reduction in cellular proliferation in a MgO-concentration-dependent manner. Finally, the results obtained on human skin fibroblasts revealed that the use MgO NPs did not alter at all both the vitality and proliferation of healthy cells.

Effectiveness of Cerium Oxide Nanoparticles in Non-Alcoholic Fatty Liver Disease Evolution Using In Vivo and In Vitro Studies: A Systematic Review

Nonalcoholic fatty liver disease (NAFLD) describes a spectrum of liver abnormalities, from benign steatosis to nonalcoholic steatohepatitis (NASH). Because of their antioxidant capabilities, CeNPs have sparked a lot of interest in biological applications. This review evaluated the effectiveness of CeNPs in NAFLD evolution through in vivo and in vitro studies. Databases such as MEDLINE, EMBASE, Scopus, and Web of Science were looked for studies published between 2012 and June 2023. Quality was evaluated using PRISMA guidelines. We looked at a total of nine primary studies in English carried out using healthy participants or HepG2 or LX2 cells. Quantitative data such as blood chemical markers, lipid peroxidation, and oxidative status were obtained from the studies. Our findings indicate that NPs are a possible option to make medications safer and more effective. In fact, CeNPs have been demonstrated to decrease total saturated fatty acids and foam cell production (steatosis), reactive oxygen species production and TNF-α (necrosis), and vacuolization in hepatic tissue when used to treat NAFLD. Thus, CeNP treatment may be considered promising for liver illnesses. However, limitations such as the variation in durations between studies and the utilization of diverse models to elucidate the etiology of NAFLD must be considered. Future studies must include standardized NAFLD models.

The Impressive Anti-Inflammatory Activity of Cerium Oxide Nanoparticles: More than Redox?

Cerium oxide nanoparticles (CNPs) are biocompatible nanozymes exerting multifunctional biomimetic activities, including superoxide dismutase (SOD), catalase, glutathione peroxidase, photolyase, and phosphatase. SOD- and catalase-mimesis depend on Ce3+/Ce4+ redox switch on nanoparticle surface, which allows scavenging the most noxious reactive oxygen species in a self-regenerating, energy-free manner. As oxidative stress plays pivotal roles in the pathogenesis of inflammatory disorders, CNPs have recently attracted attention as potential anti-inflammatory agents. A careful survey of the literature reveals that CNPs, alone or as constituents of implants and scaffolds, strongly contrast chronic inflammation (including neurodegenerative and autoimmune diseases, liver steatosis, gastrointestinal disorders), infections, and trauma, thereby ameliorating/restoring organ function. By general consensus, CNPs inhibit inflammation cues while boosting the pro-resolving anti-inflammatory signaling pathways. The mechanism of CNPs' anti-inflammatory effects has hardly been investigated, being rather deductively attributed to CNP-induced ROS scavenging. However, CNPs are multi-functional nanozymes that exert additional bioactivities independent from the Ce3+/Ce4+ redox switch, such as phosphatase activity, which could conceivably mediate some of the anti-inflammatory effects reported, suggesting that CNPs fight inflammation via pleiotropic actions. Since CNP anti-inflammatory activity is potentially a pharmacological breakthrough, it is important to precisely attribute the described effects to one or another of their nanozyme functions, thus achieving therapeutic credibility.

Infrared spectroscopy analysis determining secondary structure change in albumin by cerium oxide nanoparticles

Cerium oxide (CeO2) nanoparticles are expected to have applications in the biomedical field because of their antioxidative properties. Inorganic nanoparticles interact with proteins at the nanoparticle surface and change their conformation when administered; however, the principle underlying this interaction is still unclear. This study aimed to investigate the secondary structural changes occurring in bovine serum albumin (BSA) mixed with CeO2 nanoparticles having different surface modifications using Fourier transform infrared spectroscopy. CeO2 nanoparticles (diameter: 240 nm) were synthesized from an aqueous cerium (III) nitrate solution using a homogeneous precipitation method. The surfaces of the nanoparticles were modified by the catechol compounds dopamine and 3,4-dihydroxyhydrocinnamic acid (DHCA). In the presence of these CeO2 nanoparticles (0.11-0.43 mg/mL), β-sheet formation of BSA (30 mg/mL) was promoted especially on the amine-modified (positively charged) nanoparticles. The local concentration of BSA on the surface of the positively charged nanoparticles may have resulted in structural changes due to electrostatic and other interactions with BSA. Further investigations of the interaction mechanism between nanoparticles and proteins are expected to lead to the safe biomedical applications of inorganic nanoparticles.

Evaluation of Apical and Molecular Effects of Algae Pseudokirchneriella subcapitata to Cerium Oxide Nanoparticles

Cerium oxide engineered nanoparticles (nCeO₂) are widely used in various applications and are, also, increasingly being detected in different environmental matrixes. However, their impacts on the aquatic environment remain poorly quantified. Hence, there is a need to investigate their effects on non-target aquatic organisms. Here, we evaluated the cytotoxic and genotoxic effects of <25 nm uncoated-nCeO₂ on algae Pseudokirchneriella subcapitata. Apical (growth and chlorophyll a (Chl a) content) and genotoxic effects were investigated at 62.5-1000 µg/L after 72 and 168 h. Results demonstrated that nCeO₂ induced significant growth inhibition after 72 h and promotion post 96-168 h. Conversely, nCeO₂ induced enhanced Chl a content post 72 h, but no significant changes were observed between nCeO₂-exposed and control samples after 168 h. Hence, the results indicate P. subcapitata photosynthetic system recovery ability to nCeO₂ effects under chronic-exposure conditions. RAPD-PCR profiles showed the appearance and/or disappearance of normal bands relative to controls; indicative of DNA damage and/or DNA mutation. Unlike cell recovery observed post 96 h, DNA damage persisted over 168 h. Thus, sub-lethal nCeO₂-induced toxicological effects may pose a more serious threat to algae than at present anticipated.

Design and synthesis of Ag NPs/chitosan-starch nano-biocomposite as a modern anti-human malignant melanoma drug

In recent years, the unprecedented increase in various cancers such as melanoma has caused researchers to focus more on the formulation of newer drugs with less side effects. In this study, we herein indicate the biogenic nanoarchitechtonics of Ag NPs template over chitosan/starch mixed hydrogel having notable reducing potential and anti-malignant melanoma effects. The two biopolymers also could stabilize as-synthesized Ag NPs. Physicochemical features of the material were further characterized over a range of advanced methods like X-ray diffraction (XRD), elemental mapping, dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Fourier transformed infrared spectroscopy (FT-IR). TEM analysis showed the spherical-shaped nanocomposite with the mean diameter in the range of 5-15 nm. Thereafter, the nanocomposite was exploited in the anti-malignant melanoma and cytotoxicity effects studies against various human malignant melanoma cell lines (HT144, RPMI7951, SKMEL2, UACC3074, WM266-4 and MUM2C) in situ. The bio-composite corresponding IC₅₀ values were 193, 102, 227, 250, 301, and 203 μg/mL against MUM2C, WM266-4, UACC3074, SKMEL2, RPMI7951, and HT144 cell lines, respectively. A significantly high IC₅₀ value offered an excellent antioxidant capacity of bio-composite. According to the above results, Ag NPs/CS-Starch nanomaterial can be utilized as an efficient drug to treat malignant melanoma in humans after doing clinical trial studies.

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 (d_avg) 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.

From Low to High Saturation Magnetization in Magnetite Nanoparticles: The Crucial Role of the Molar Ratios Between the Chemicals

In this study, a comprehensive characterization of iron oxide nanoparticles synthesized by using a simple one-pot thermal decomposition route is presented. In order to obtain monodisperse magnetite nanoparticles with high saturation magnetization, close to the bulk material, the molar ratios between the starting materials (solvents, reducing agents, and surfactants) were varied. Two out of nine conditions investigated in this study resulted in monodisperse iron oxide nanoparticles with high saturation magnetization (90 and 93% of bulk magnetite). The X-ray diffraction analyses along with the inspection of the lattice structure through transmission electron micrographs revealed that the main cause of the reduced magnetization in the other seven samples is likely due to the presence of distortion and microstrain in the particles. Although the thermogravimetric analysis, Raman and Fourier transform infrared spectroscopies confirmed the presence of covalently bonded oleic acid on the surface of all the samples, the particles with higher polydispersity and the lowest surface coating molecules showed the lowest saturation magnetization. Based on the observed results, it could be speculated that the changes in the kinetics of the reactions, induced by varying the molar ratio of the starting chemicals, can lead to the production of the particles with higher polydispersity and/or lattice deformation in their crystal structures. Finally, it was concluded that the experimental conditions for obtaining high-quality iron oxide nanoparticles, particularly the molar ratios and the heating profile, should not be chosen independently; for any specific molar ratio, there may exist a specific heating profile or vice versa. Because this synthetic consideration has rarely been reported in the literature, our results can give insights into the design of iron oxide nanoparticles with high saturation magnetization for different applications.

In vivo study of dose-dependent antioxidant efficacy of functionalized core-shell yttrium oxide nanoparticles

Abstract

Herein, we assess the dose-dependent antioxidant efficacy of ultrafine spherical functionalized core–shell yttrium oxide nanoparticles (YNPs) with a mean size of 7–8 nm and modified with poly EGMP (ethylene glycol methacrylate phosphate) and N-Fluorescein Acrylamide. The antioxidant properties of these nanoparticles were investigated in three groups of Sprague–Dawley rats (10 per group) exposed to environmental stress daily for 1 week and one control group. Groups 2 and 3 were intravenously injected twice a week with YNPs at 0.3 and 0.5 mg at 2nd and 5th day of environmental stress exposure respectively. Different samples of blood and serum were collected from all experimental groups at end of the experiment to measure oxidative biomarkers such as total antioxidant capacity (TAC), hydroxyl radical antioxidant capacity (HORAC), oxygen radical antioxidant capacity (ORAC), malondialdehyde (MDA), and oxidants concentration as hydrogen peroxide (H₂O₂). The liver, brain, and spleen tissues were collected for fluorescence imaging and histopathological examination in addition to brain tissue examination by transmission electron microscope (TEM). Inductively coupled plasma-mass spectrometry (ICP-MS) was used to estimate YNPs translocation and concentration in tissues which is consecutively dependent on the dose of administration. Depending on all results, poly EGMP YNPs (poly EGMP yttrium oxide nanoparticles) can act as a potent direct antioxidant in a dose-dependent manner with good permeability through blood–brain barrier (BBB). Also, the neuroprotective effect of YNPs opening the door to a new therapeutic approach for modulating oxidative stress–related neural disorders.

Highlights

• The dose-dependent antioxidant efficacy of ultrafine spherical functionalized core–shell yttrium oxide nanoparticles (YNPs) with a mean size of 7–8 nm and modified with poly EGMP (ethylene glycol methacrylate phosphate) and N-Fluorescein Acrylamide was assessed.

• The dose of administration directly affecting the brain, liver, and spleen tissues distribution, retention, and uptake of YNPs and direct correlation between the absorbed amount and higher dose administered.

• YNPs can act as a potent direct antioxidant in a dose-dependent manner with good permeability through blood–brain barrier (BBB).

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s00210-022-02219-1.

Weak Ferromagnetism in a One-Orbital Double-Exchange Model with Ising Spins for Cerium Oxides

Cerium oxides (ceria) are materials that exhibit weak, room-temperature ferromagnetism without d-electrons. The latter are usually responsible for magnetism in a variety of other oxide compounds, but the underlying mechanism for such a magnetic response in ceria without the d-electrons (d0-magnetism) is still under debate. A possible explanation is Zener double-exchange, where itinerant electrons polarize the localized spins via Hund-coupling as they hop from site to site. Here, we report magnetization and spin-spin correlation results using various values of the Hund-coupling in a one-orbital double-exchange model with Ising spins. In the real material with formula CeO2−x, the oxygen-deficient sites are denoted by x. These sites are related to the density of tetravalent cerium spins (the Ising spin background in our model), which we denoted as and set at N=0.50 in our simulations. Our results at this value of localized spin concentration show ferromagnetic tendencies at low carrier densities (n=0.25). However, ferromagnetism is lost at intermediate carrier concentrations (n=0.50) due to charge localization at high temperatures, as evident from density of states calculations and Monte Carlo snapshots. To our knowledge, our study based on a realistic Zener-type double exchange mechanism is a first in the study of magnetism in cerium oxides. Our results are also consistent with previous studies using similar Hamiltonians in the context of diluted magnetic semiconductors, where Heisenberg spins were used.

Oxygen in Metabolic Dysfunction and Its Therapeutic Relevance

Significance: In recent years, a number of studies have shown altered oxygen partial pressure at a tissue level in metabolic disorders, and some researchers have considered oxygen to be a (macro) nutrient. Oxygen availability may be compromised in obesity and several other metabolism-related pathological conditions, including sleep apnea-hypopnea syndrome, the metabolic syndrome (which is a set of conditions), type 2 diabetes, cardiovascular disease, and cancer. Recent Advances: Strategies designed to reduce adiposity and its accompanying disorders have been mainly centered on nutritional interventions and physical activity programs. However, novel therapies are needed since these approaches have not been sufficient to counteract the worldwide increasing rates of metabolic disorders. In this regard, intermittent hypoxia training and hyperoxia could be potential treatments through oxygen-related adaptations. Moreover, living at a high altitude may have a protective effect against the development of abnormal metabolic conditions. In addition, oxygen delivery systems may be of therapeutic value for supplying the tissue-specific oxygen requirements. Critical Issues: Precise in vivo methods to measure oxygenation are vital to disentangle some of the controversies related to this research area. Further, it is evident that there is a growing need for novel in vitro models to study the potential pathways involved in metabolic dysfunction to find appropriate therapeutic targets. Future Directions: Based on the existing evidence, it is suggested that oxygen availability has a key role in obesity and its related comorbidities. Oxygen should be considered in relation to potential therapeutic strategies in the treatment and prevention of metabolic disorders. Antioxid. Redox Signal. 35, 642-687.

Evaluation of the Anticancer Activity of Phytomolecules Conjugated Gold Nanoparticles Synthesized by Aqueous Extracts of Zingiber officinale (Ginger) and Nigella sativa L. Seeds (Black Cumin)

The conventional physical and chemical synthetic methods for the preparation of metal nanoparticles have disadvantages as they use expensive equipment and hazardous chemicals which limit their applications for biomedical purposes, and are not environment friendly. However, for the synthesis of biocompatible nanomaterials, plant-based techniques are eco-friendly and easy to handle. Herein a simple, single-step biosynthesis of gold nanoparticles using aqueous extracts of Nigella sativa (NSE) and Zingiber officinale (GE) as a reducing and capping agent has been demonstrated. The formation of gold nanoparticles (Au NPs) was confirmed by X-ray diffraction, UV-Vis, and EDS spectroscopies. Spectroscopic and chromatographic analysis of GE and NSE revealed the presence of bioactive phytochemical constituents, such as gingerol, thymoquinone, etc., which successfully conjugated the surface of resulting Au NPs. TEM analysis indicated the formation of smaller-sized, less-aggregated, spherical-shaped Au NPs both in the case of GE (~9 nm) and NSE (~11 nm). To study the effect of the concentration of the extracts on the quality of resulting NPs and their anticancer properties, three different samples of Au NPs were prepared from each extract by varying the concentration of extracts while keeping the amount of precursor constant. In both cases, high-quality, spherical-shaped NPs were obtained, only at a high concentration of the extract, whereas at lower concentrations, larger-sized, irregular-shaped NPs were formed. Furthermore, the as-prepared Au NPs were evaluated for the anticancer properties against two different cell lines including MDA-MB-231 (breast cancer) and HCT 116 (colorectal cancer) cell lines. GE-conjugated Au NPs obtained by using a high concentration of the extract demonstrated superior anticancer properties when compared to NSE-conjugated counterparts.

Intracellular and extracellular targets as mechanisms of cancer therapy by nanomaterials in relation to their physicochemical properties

Cancer nanomedicine has evolved in recent years and is only expected to increase due to the ease with which nanomaterials (NMs) may be manipulated to the advantage of the cancer patient. The success of nanomedicine is dependent on the cell death mechanism, which in turn is dependent on the organelle initially targeted. The success of cancer nanomedicine is also dependent on other cellular mechanisms such as the induction of autophagy dysfunction, manipulation of the tumor microenvironment (TME) and secretome or induction of host immune responses. Current cancer phototherapies for example, photothermal- or photodynamic therapies as well as radio enhancement also form a major part of cancer nanomedicine. In general, cancer nanomedicine may be grouped into those NMs exhibiting inherent anti-cancer properties that is, self-therapeutic NMs (Group 1), NMs leading to localization of phototherapies or radio-enhancement (Group 2), and NMs as nanocarriers in the absence or presence of external radiation (Group 3). The recent advances of these three groups, together with their advantages and disadvantages as well as their cellular mechanisms and ultimate outcomes are summarized in this review. By exploiting these different intracellular mechanisms involved in initiating cell death pathways, it is possible to synthesize NMs that may have the desirable characteristics to maximize their efficacy in cancer therapy. Therefore, a summary of these important physicochemical characteristics is also presented that need to be considered for optimal cancer cell targeting and initiation of mechanisms that will lead to cancerous cell death. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

The potential ameliorative impacts of cerium oxide nanoparticles against fipronil-induced hepatic steatosis

Fipronil (FIP) is a phenylpyrazole insecticide that is commonly used in agricultural and veterinary fields for controlling a wide range of insects, but it is a strong environmentally toxic substance. Exposure to FIP has been reported to increase the hepatic fat accumulation through altered lipid metabolism, which ultimately can contribute to nonalcoholic fatty liver disease (NAFLD) development. The present study aimed to examine the function of cerium oxide nanoparticles (CeNPs) in protecting against hepatotoxicity and lipogenesis induced by FIP. Twenty-eight male albino rats were classified into four groups: FIP (5 mg/kg/day per os), CTR, CeNPs (35 mg/kg/day p.o.), and FIP + CeNPs (5 (FIP) + 35 (CeNPs) mg/kg/day p.o.) for 28 consecutive days. Serum lipid profiles, hepatic antioxidant parameters and pathology, and mRNA expression of adipocytokines were assessed. The results revealed that FIP increased cholesterol, height-density lipoprotein, triacylglyceride, low-density lipoprotein (LDL-c), and very-low-density lipoprotein (VLDL-c) concentrations. It also increased nitric oxide (NO) and malondialdehyde (MDA) hepatic levels and reduced glutathione peroxidase (GPx) and superoxide dismutase (SOD) enzyme activities. Additionally, FIP up-regulated the fatty acid-binding protein (FABP), acetyl Co-A carboxylase (ACC1), and peroxisome proliferator-activated receptor-alpha (PPAR-α). Immunohistochemically, a strong proliferation of cell nuclear antigen (PCNA), ionized calcium-binding adapter molecule 1 (Iba-1), cyclooxygenase-2 (COX-2) reactions in the endothelial cells of the hepatic sinusoids, and increased expression of caspase3 were observed following FIP intoxication. FIP also caused histological changes in hepatic tissue. The CeNPs counteracted the hepatotoxic effect of FIP exposure. So, this study recorded an ameliorative effect of CeNPs against FIP-induced hepatotoxicity.

Surface refined AuQuercetin nanoconjugate stimulates dermal cell migration: possible implication in wound healing

Refining nutraceutical conjugated metal nanoparticles (NPs) and understanding their interactions with the cellular micro-environment is necessary for their application in nanomedicine. In the present experiment, we studied the effect of quercetin functionalized gold nanoparticles (Au^QurNP) on skin fibroblast and keratinocyte cell migration. Spherical shaped Au^QurNPs of 47 nm in size were formed due to the interaction of hydroxyl and carbonyl groups of quercetin with Au atoms as revealed by incremental algorithm-based analysis. Au^QurNP containing up to 5 μg l⁻¹ of Au with quercetin (5.2 ± 1.6 ng ml⁻¹) was least toxic to fibroblasts. Au^QurNP effectively reduced the generation of intracellular ROS (up to 63%) through free-radical scavenging activity. Au^QurNP also enhanced the rate of migration of fibroblasts (24 h) and keratinocytes (20 h) in artificially created wounds. The rate of migration of the cells towards the wound edge was in the order of Au^QurNP > control > quercetin > AuNP. Au^QurNP also significantly increased the expression of TGFβ1 protein, thereby inducing the downstream SMAD complex (SMAD 2–4). Downregulation of the inhibitory protein SMAD 7 by Au^QurNP helped in the nuclear translocation of SMADs 3 and 4. Collectively, the present in vitro study demonstrates the action of Au^QurNP on the SMAD family and the interconnected molecular mechanism leading to the cell migration process.

Au^Quercetin nano conjugates enhances cell migration via TGFβ1.

In-vitro interaction of cerium oxide nanoparticles with hemoglobin, insulin, and dsDNA at 310.15 K: Physicochemical, spectroscopic and in-silico study

Lanthanide nanoparticles and nanorods especially their biocompatible oxide forms like cerium oxide nanoparticles (CNPs) with therapeutic applications are used to cure neurological oxidative stresses. Thus it tempts to study their biocompatible aspects by interactions with several biologically significant molecules. In-Vitro interactions of 15-240 μM CNPs with water, Phosphate buffered saline (PBS), DMEM media, Insulin (Ins) hemoglobin (Hb) and ds-DNA at 37 °C were studied. Their physicochemical properties study by Borosil Mansingh Survismeter (BMS) showed the first order interaction with the protein-protein structure breaking behaviour of CNPs with Hb, Ins, and DNA. Zeta potential measurements of CNPs in different biological medium show a net increase in negative charge magnitude with good colloidal stability. K_b = 4 × 106 mM^-1 of CNPs-DNA infer noncovalent interactions. Circular dichroism and FTIR revealed a loss of secondary conformation with increasing CNPs concentration. In-silico molecular docking depicts CNP interaction via conventional hydrogen bonding, carbon hydrogen bonding and electrostatic interactions at the minor groove of DNA. The study reports in-dept unfolding functional mechanism investigated by physicochemical, spectroscopic, and In-Silico approaches of protein on interactions with CNPs for safer-by-design use in medicine and pharmaceutics. Fundamentally the CeO₂ in ~62% and Ce₂O₃ in ~38% with Ce⁴⁺ and Ce³⁺ oxidation potentials develop a unique case of electronic configurations with 4f⁰5d⁰6s⁰ and 4f¹5d⁰6s⁰ electrons respectively which these studies a novel one.

Cellular Responses of Human Lymphatic Endothelial Cells to Carbon Nanomaterials

One of the greatest challenges to overcome in the pursuit of the medical application of carbon nanomaterials (CNMs) is safety. Particularly, when considering the use of CNMs in drug delivery systems (DDSs), evaluation of safety at the accumulation site is an essential step. In this study, we evaluated the toxicity of carbon nanohorns (CNHs), which are potential DDSs, using human lymph node endothelial cells that have been reported to accumulate CNMs, as a comparison to fibrous, multi-walled carbon nanotubes (MWCNTs) and particulate carbon black (CB). The effect of different surface characteristics was also evaluated using two types of CNHs (untreated and oxidized). In the fibrous MWCNT, cell growth suppression, as well as expression of inflammatory cytokine genes was observed, as in previous reports. In contrast, no significant toxicity was observed for particulate CB and CNHs, which was different from the report of CB cytotoxicity in vascular endothelial cells. These results show that (1) lymph endothelial cells need to be tested separately from other endothelial cells for safety evaluation of nanomaterials, and (2) the potential of CNHs as DDSs.

Green Synthesis of Zinc Oxide Nanoparticles via Algal Route and its Action on Cancerous Cells and Pathogenic Microbes

Application of metal oxide nanoparticles for treatment of melanoma cells and microbes is being investigated. Zinc oxide nanoparticles (ZnO NPs) deserve special mention where particles cause destruction of melanoma cells with minimal damage to healthy cells. In the present study, pure phase ZnO NPs with particle size of 3.1 nm were synthesized by green route using algal extract. Skin melanoma (B16F10) cells were treated with synthesized ZnO NP and compared with commercial ZnO NPs and analysed for ED50 for cellular viability using 3% (w/v) of the doses. Sensitivity of B16F10 cells towards green synthesized ZnO NP was found to be more than commercial ZnO NPs. Results showed greater reduction in viability of cells exposed to green synthesized ZnO NPs and with increasing dose of the ZnO NPs, percentage viability of cells gradually reduced. 50% decrease in cellular viability (ED50) was obtained for green synthesized ZnO NP at 3% dose while commercial ZnO exhibited ED50 at 6% of doses. The ZnO NP also showed antimicrobial activity against Pseudomonas sp. and Staphylococcus sp. Zone of inhibition (ZOI) exhibited by Pseudomonas aeruginosa and Staphylococcus aureus for disc diffusion and well diffusion assay was around 10-22 mm and 9-12mm respectively.

Uptake of Cerium Dioxide Nanoparticles and Impact on Viability, Differentiation and Functions of Primary Trophoblast Cells from Human Placenta

The human placenta is at the interface between maternal and fetal circulations, and is crucial for fetal development. The nanoparticles of cerium dioxide (CeO₂ NPs) from air pollution are an unevaluated risk during pregnancy. Assessing the consequences of placenta exposure to CeO₂ NPs could contribute to a better understanding of NPs’ effect on the development and functions of the placenta and pregnancy outcome. We used primary villous cytotrophoblasts purified from term human placenta, with a wide range of CeO₂ NPs concentrations (0.1–101 μg/cm²) and exposure time (24–72 h), to assess trophoblast uptake, toxicity and impact on trophoblast differentiation and endocrine function. We have shown the capacity of both cytotrophoblasts and syncytiotrophoblasts to internalize CeO₂ NPs. CeO₂ NPs affected trophoblast metabolic activity in a dose and time dependency, induced caspase activation and a LDH release in the absence of oxidative stress. CeO₂ NPs decreased the fusion capacity of cytotrophoblasts to form a syncytiotrophoblast and disturbed secretion of the pregnancy hormones hCG, hPL, PlGF, P4 and E2, in accordance with NPs concentration. This is the first study on the impact of CeO₂ NPs using human primary trophoblasts that decrypts their toxicity and impact on placental formation and functions.

Cell Proliferation to Evaluate Preliminarily the Presence of Enduring Self-Regenerative Antioxidant Activity in Cerium Doped Bioactive Glasses

(1) Background: a cell evaluation focused to verify the self-regenerative antioxidant activity is performed on cerium doped bioactive glasses. (2) Methods: the glasses based on 45S5 Bioglass^®, are doped with 1.2 mol%, 3.6 mol% and 5.3 mol% of CeO₂ and possess a polyhedral shape (~500 µm²). Glasses with this composition inhibit oxidative stress by mimicking catalase enzyme (CAT) and superoxide dismutase (SOD) activities; moreover, our previous cytocompatibility tests (neutral red (NR), 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Bromo-2-deoxyUridine (BrdU)) reveal that the presence of cerium promotes the absorption and vitality of the cells. The same cytocompatibility tests were performed and repeated, in two different periods (named first and second use), separated from each other by four months. (3) Results: in the first and second use, NR tests indicate that the presence of cerium promotes once again cell uptake and viability, especially after 72 h. A decrease in cell proliferation it is observed after MTT and BrdU tests only in the second use. These findings are supported by statistically significant results (4) Conclusions: these glasses show enhanced proliferation, both in the short and in the long term, and for the first time such large dimensions are studied for this kind of study. A future prospective is the implantation of these bioactive glasses as bone substitute in animal models.

Nanomaterials for Angiogenesis in Skin Tissue Engineering

Damage to skin tissue, which causes the disorder of the patient's body homeostasis, threatens the patient's life and increases the personal and social treatment burden. Angiogenesis, a key step in the wound healing process, provides sufficient oxygen and nutrients to the wound area. However, traditional clinical interventions are not enough to stabilize the formation of the vascular system to support wound healing. Due to the unique properties and multiple functions of nanomaterials, it has made a major breakthrough in the application of medicine. Nanomaterials provide a more effective treatment to hasten the angiogenesis and wound healing, by stimulating fundamental factors in the vascular regeneration phase. In the present review article, the basic stages and molecular mechanisms of angiogenesis are analyzed, and the types, applications, and prospects of nanomaterials used in angiogenesis are detailed. Impact statement Wound healing (especially chronic wounds) is currently a clinically important issue. The long-term nonhealing of chronic wounds often plagues patients, medical systems, and causes huge losses to the social economy. There is currently no effective method of treating chronic wounds in the clinic. Angiogenesis is an important step in wound healing. Nanomaterials had properties that are not found in conventional materials, and they have been extensively studied in angiogenesis. This review article provides readers with the molecular mechanisms of angiogenesis and the types and applications of angiogenic nanomaterials, hoping to bring inspiration to overcome chronic wounds.

Chemical Mechanisms of Nanoparticle Radiosensitization and Radioprotection: A Review of Structure-Function Relationships Influencing Reactive Oxygen Species

Metal nanoparticles are of increasing interest with respect to radiosensitization. The physical mechanisms of dose enhancement from X-rays interacting with nanoparticles has been well described theoretically, however have been insufficient in adequately explaining radiobiological response. Further confounding experimental observations is examples of radioprotection. Consequently, other mechanisms have gained increasing attention, especially via enhanced production of reactive oxygen species (ROS) leading to chemical-based mechanisms. Despite the large number of variables differing between published studies, a consensus identifies ROS-related mechanisms as being of significant importance. Understanding the structure-function relationship in enhancing ROS generation will guide optimization of metal nanoparticle radiosensitisers with respect to maximizing oxidative damage to cancer cells. This review highlights the physico-chemical mechanisms involved in enhancing ROS, commonly used assays and experimental considerations, variables involved in enhancing ROS generation and damage to cells and identifies current gaps in the literature that deserve attention. ROS generation and the radiobiological effects are shown to be highly complex with respect to nanoparticle physico-chemical properties and their fate within cells. There are a number of potential biological targets impacted by enhancing, or scavenging, ROS which add significant complexity to directly linking specific nanoparticle properties to a macroscale radiobiological result.

Physicochemical interaction of cerium oxide nanoparticles with simulated biofluids, hemoglobin, insulin, and ds-DNA at 310.15 K

Interaction study in cerium oxide nanoparticles with biofluids and biomolecules via physicochemical, spectroscopic and in silico analytical approaches, showing conformational change.

Cerium Oxide Nanoparticles Absorption through Intact and Damaged Human Skin

Cerium oxide (CeO2) nanoparticles (NPs) are used in polishing products and absorbents, as promoters in wound healing, and as organopesticide decontaminants. While systemic bioaccumulation and organ toxicity has been described after inhalation, data on CeO2 NPs' transdermal permeation are lacking. Our study was an in vitro investigation of the permeation of 17-nm CeO2 NPs dispersed in synthetic sweat (1 g L-1) using excised human skin on Franz cells. Experiments were performed using intact and needle-abraded skin, separately. The average amount of Ce into intact and damaged skin samples was 3.64 ± 0.15 and 7.07 ± 0.78 µg cm-2, respectively (mean ± SD, p = 0.04). Ce concentration in the receiving solution was 2.0 ± 0.4 and 3.3 ± 0.7 ng cm-2 after 24 h (p = 0.008). The Ce content was higher in dermal layers of damaged skin compared to intact skin (2.93 ± 0.71 µg cm-2 and 0.39 ± 0.16 µg cm-2, respectively; p = 0.004). Our data showed a very low dermal absorption and transdermal permeation of cerium, providing a first indication of Ce skin uptake due to contact with CeO2.

Functionalized cerium oxide nanoparticles mitigate the oxidative stress and pro-inflammatory activity associated to the portal vein endothelium of cirrhotic rats

BACKGROUND AND AIMS

The occurrence of endothelial alterations in the liver and in the splanchnic vasculature of cirrhotic patients and experimental models of liver diseases has been demonstrated. However, the pathological role of the portal vein endothelium in this clinical context is scarcely studied and, therefore, deserves attention. In this context, we aimed to investigate whether pathological endothelial activation occurs in the portal vein of cirrhotic rats.

METHODS

Cirrhosis was induced in wistar rats by CCl4 inhalation. We generated immortalized endothelial cells from the portal vein of control (CT-iPVEC) and cirrhotic rats (CH-iPVEC) by retroviral transduction of the SV40 T antigen. We assessed differential gene expression and intracellular reactive oxygen species (ROS) levels in iPVECs and in portal veins of control and cirrhotic rats. Finally, we assessed the therapeutic effectiveness of cerium oxide nanoparticles (CeO2NP) on reversing PVEC activation and macrophage polarization.

RESULTS

CH-iPVECs overexpressed collagen-I, endothelin-1, TIMP-1, TIMP-2, IL-6 and PlGF genes. These results were consistent with the differential expression showed by whole portal veins from cirrhotic rats. In addition, CH-iPVECs showed a significant increase in intracellular ROS and the capacity of potentiating M1 polarization in macrophages. The treatment of CH-iPVECs with CeO2NPs blocked intracellular ROS formation and IL-6 and TIMP-2 gene overexpression. In agreement with the in vitro results, the chronic treatment of cirrhotic rats with CeO2NPs also resulted in the blockade of both ROS formation and IL-6 gene overexpression in whole portal veins.

CONCLUSIONS

Endothelial cells from portal vein of cirrhotic rats depicted an abnormal phenotype characterized by a differential gene expression and the induction of M1 polarization in macrophages. We identified the excess of intracellular reactive oxygen species (ROS) as a major contributor to this altered phenotype. In addition, we demonstrated the utility of the nanomaterial cerium oxide as an effective antioxidant capable of reverse some of these pathological features associated with the portal vein in the cirrhosis condition.

Synthesis and anticancer properties of bacterial cellulose-magnesium oxide bionanocomposite

Given the increase in global mortality rate due to various types of cancer, the present study aimed to develop optimal conditions for the synthesis of cellulose-magnesium oxide nanocomposite with favorable anticancer activity. For this purpose, the Taguchi method was used to design nine experiments with varied ratios of cellulose biopolymer, magnesium oxide nanoparticles and different stirring times. The scanning electron microscopy (SEM) images confirmed the formation of cellulose-magnesium oxide nanocomposite. The anticancer activity level of nine nanocomposites studied was evaluated using MTT assay on Michigan Cancer Foundation-7 (MCF-7) cell line. The nanocomposite synthesized in experiment 9 (8 mg/ml of magnesium oxide, 2 mg/ml of cellulose and stirring time of 60 min) showed the highest growth inhibitory activity on the cancer cells. Based on the attained results,e cellulose-magnesium oxide nanocomposite synthesized in optimal conditions can be used as an eligible anticancer agent.

Cerium Oxide Nanoparticles Regulate Insulin Sensitivity and Oxidative Markers in 3T3-L1 Adipocytes and C2C12 Myotubes

Insulin resistance is associated with oxidative stress, mitochondrial dysfunction, and a chronic low-grade inflammatory status. In this sense, cerium oxide nanoparticles (CeO₂ NPs) are promising nanomaterials with antioxidant and anti-inflammatory properties. Thus, we aimed to evaluate the effect of CeO₂ NPs in mouse 3T3-L1 adipocytes, RAW 264.7 macrophages, and C2C12 myotubes under control or proinflammatory conditions. Macrophages were treated with LPS, and both adipocytes and myotubes with conditioned medium (25% LPS-activated macrophages medium) to promote inflammation. CeO₂ NPs showed a mean size of ≤25.3 nm (96.7%) and a zeta potential of 30.57 ± 0.58 mV, suitable for cell internalization. CeO₂ NPs reduced extracellular reactive oxygen species (ROS) in adipocytes with inflammation while increased in myotubes with control medium. The CeO₂ NPs increased mitochondrial content was observed in adipocytes under proinflammatory conditions. Furthermore, the expression of Adipoq and Il10 increased in adipocytes treated with CeO₂ NPs. In myotubes, both Il1b and Adipoq were downregulated while Irs1 was upregulated. Overall, our results suggest that CeO₂ NPs could potentially have an insulin-sensitizing effect specifically on adipose tissue and skeletal muscle. However, further research is needed to confirm these findings.

Cerium Oxide Nanoparticles Re-establish Cell Integrity Checkpoints and Apoptosis Competence in Irradiated HaCat Cells via Novel Redox-Independent Activity

Cerium oxide nanoparticles (CNPs) are potent radical scavengers protecting cells from oxidative insults, including ionizing radiation. Here we show that CNPs prevent X-ray-induced oxidative imbalance reducing DNA breaks on HaCat keratinocytes, nearly abating mutagenesis. At the same time, and in spite of the reduced damage, CNPs strengthen radiation-induced cell cycle arrest and apoptosis outcome, dropping colony formation; notably, CNPs do not possess any intrinsic toxicity toward non-irradiated HaCat, indicating that they act on damaged cells. Thus CNPs, while exerting their antioxidant action, also reinforce the stringency of damage-induced cell integrity checkpoints, promoting elimination of the “tolerant” cells, being in fact radio-sensitizers. These two contrasting pathways are mediated by different activities of CNPs: indeed Sm-doped CNPs, which lack the Ce³⁺/Ce⁴⁺ redox switch and the correlated antioxidant action, fail to decrease radiation-induced superoxide formation, as expected, but surprisingly maintain the radio-sensitizing ability and the dramatic decrease of mutagenesis. The latter is thus attributable to elimination of damaged cells rather than decreased oxidative damage. This highlights a novel redox-independent activity of CNPs, allowing selectively eliminating heavily damaged cells through non-toxic mechanisms, rather reactivating endogenous anticancer pathways in transformed cells.

Impact of Lanthanide Nanomaterials on Photonic Devices and Smart Applications

Half a century after its initial emergence, lanthanide photonics is facing a profound remodeling induced by the upsurge of nanomaterials. Lanthanide-doped nanomaterials hold promise for bioapplications and photonic devices because they ally the unmatched advantages of lanthanide photophysical properties with those arising from large surface-to-volume ratios and quantum confinement that are typical of nanoobjects. Cutting-edge technologies and devices have recently arisen from this association and are in turn promoting nanophotonic materials as essential tools for a deeper understanding of biological mechanisms and related medical diagnosis and therapy, and as crucial building blocks for next-generation photonic devices. Here, the recent progress in the development of nanomaterials, nanotechnologies, and nanodevices for clinical uses and commercial exploitation is reviewed. The candidate nanomaterials with mature synthesis protocols and compelling optical uniqueness are surveyed. The specific fields that are directly driven by lanthanide doped nanomaterials are emphasized, spanning from in vivo imaging and theranostics, micro-/nanoscopic techniques, point-of-care medical testing, forensic fingerprints detection, to micro-LED devices.

Not Only Redox: The Multifaceted Activity of Cerium Oxide Nanoparticles in Cancer Prevention and Therapy

Much information is accumulating on the effect of cerium oxide nanoparticles (CNPs) as cell-protective agents, reducing oxidative stress through their unique ability of scavenging noxious reactive oxygen species via an energy-free, auto-regenerative redox cycle, where superoxides and peroxides are sequentially reduced exploiting the double valence (Ce³⁺/Ce⁴⁺) on nanoparticle surface. In vitro and in vivo studies consistently report that CNPs are responsible for attenuating and preventing almost any oxidative damage and pathology. Particularly, CNPs were found to exert strong anticancer activities, helping correcting the aberrant homeostasis of cancer microenvironment, normalizing stroma-epithelial communication, contrasting angiogenesis, and strengthening the immune response, leading to reduction of tumor mass in vivo. Since these homeostatic alterations are of an oxidative nature, their relief is generally attributed to CNPs redox activity. Other studies however reported that CNPs exert selective cytotoxic activity against cancer cells and sensitize cancer cells to chemotherapy- and radiotherapy-induced apoptosis: such effects are hardly the result of antioxidant activity, suggesting that CNPs exert such important anticancer effects through additional, non-redox mechanisms. Indeed, using Sm-doped CNPs devoid of redox activity, we could recently demonstrate that the radio-sensitizing effect of CNPs on human keratinocytes is independent from the redox switch. Mechanisms involving particle dissolution with release of toxic Ce⁴⁺ atoms, or differential inhibition of the catalase vs. SOD-mimetic activity with accumulation of H₂O₂ have been proposed, explaining such intriguing findings only partially. Much effort is urgently required to address the unconventional mechanisms of the non-redox bioactivity of CNPs, which may provide unexpected medicinal tools against cancer.

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.

Anticancer activity of metal nanoparticles and their peptide conjugates against human colon adenorectal carcinoma cells

In the present study, nanoparticles of gold, iron oxide and zinc oxide (ZnO) were studied for cytotoxicity in the colorectal cancer cell HT 29. The metallic nanoparticles in the range of <50 and <100 nm were screened for anticancer activity by MTT assay. The nanoparticles were tested at concentrations ranging from 0.5 to 50 µg/ml. Zinc oxide exhibited significant anti-cancer activity in comparison to other nanoparticles. It had an IC50 value of 17.12 µg/ml. The mechanism of action was studied by fluorescence microscopy with acridine orange, propidium iodide and DAPI staining techniques. The ROS production of ZnO nanoparticles was determined by DCFH-DA. The ZnO nanoparticles were conjugated with novel hydrophobic peptides and evaluated for anticancer activity. It was observed that the nanoparticles peptide complex showed better cytotoxicity than either peptide or nanoparticle alone. Thus, the ZnO nanoparticles tested in our study has anticancer activity against colon cancer cells. It can also be conjugated with peptides and used for targeting cancer cells with higher efficacy.

Advances in antimicrobial photodynamic inactivation at the nanoscale

The alarming worldwide increase in antibiotic resistance amongst microbial pathogens necessitates a search for new antimicrobial techniques, which will not be affected by, or indeed cause resistance themselves. Light-mediated photoinactivation is one such technique that takes advantage of the whole spectrum of light to destroy a broad spectrum of pathogens. Many of these photoinactivation techniques rely on the participation of a diverse range of nanoparticles and nanostructures that have dimensions very similar to the wavelength of light. Photodynamic inactivation relies on the photochemical production of singlet oxygen from photosensitizing dyes (type II pathway) that can benefit remarkably from formulation in nanoparticle-based drug delivery vehicles. Fullerenes are a closed-cage carbon allotrope nanoparticle with a high absorption coefficient and triplet yield. Their photochemistry is highly dependent on microenvironment, and can be type II in organic solvents and type I (hydroxyl radicals) in a biological milieu. Titanium dioxide nanoparticles act as a large band-gap semiconductor that can carry out photo-induced electron transfer under ultraviolet A light and can also produce reactive oxygen species that kill microbial cells. We discuss some recent studies in which quite remarkable potentiation of microbial killing (up to six logs) can be obtained by the addition of simple inorganic salts such as the non-toxic sodium/potassium iodide, bromide, nitrite, and even the toxic sodium azide. Interesting mechanistic insights were obtained to explain this increased killing.

Fullerenes in Biology and Medicine

Fullerenes and related carbon based derivatives have shown a growing relevance in biology and medicine, mainly due to the unique electronic and structural properties that make them excellent candidates for multiple functionalization. This review focuses on the most recent developments of fullerene derivatives for different biological applications.

A novel synthetic approach of cerium oxide nanoparticles with improved biomedical activity

Cerium oxide nanoparticles (CNPs) are novel synthetic antioxidant agents proposed for treating oxidative stress-related diseases. The synthesis of high-quality CNPs for biomedical applications remains a challenging task. A major concern for a safe use of CNPs as pharmacological agents is their tendency to agglomerate. Herein we present a simple direct precipitation approach, exploiting ethylene glycol as synthesis co-factor, to synthesize at room temperature nanocrystalline sub-10 nm CNPs, followed by a surface silanization approach to improve nanoparticle dispersibility in biological fluids. CNPs were characterized using transmission electron microscopy (TEM) observations, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance (1H-NMR) spectroscopy, dynamic light scattering (DLS) and zeta potential measurements. CNP redox activity was studied in abiotic systems using electron spin resonance (ESR) measurements, and in vitro on human cell models. In-situ silanization improved CNP colloidal stability, in comparison with non-functionalized particles, and allowed at the same time improving their original biological activity, yielding thus functionalized CNPs suitable for biomedical applications.