Giovanni Maina

Human skin penetration of cobalt nanoparticles through intact and damaged skin

Cobalt nanoparticles (CoNPs) are produced for several industrial and biomedical applications but there is a lack of data on human cutaneous absorption. Cobalt is also a skin sensitizer that can cause allergic contact dermatitis. Co applied as NPs, due to their small size and high surface, can penetrate into the skin in higher amount that bulk material. The aim of this study was to evaluate the absorption of Co applied as NPs in both intact and damaged skin. Experiments were performed using Franz cells and 1.0 mg cm(-2) of CoNPs was applied as donor phase for 24h. Mean Co content of 8.5 ± 1.2 ng cm(-2) and 1.87 ± 0.86 μg cm(-2) were found in the receiving solutions of Franz cells when the CoNPs suspension was applied on intact skin and on damaged skin, respectively. Twenty-four hours Co flux permeation was 76 ± 49 ng cm(-2)h(-1) in damaged skin with a lag time of 2.8 ± 2.1h. This study suggests that Co applied as NPs is able to penetrate the human skin in an in vitro diffusion cell system.

Nanoparticle dermal absorption and toxicity: a review of the literature

IntroductionNanotechnologies are among the fastest growing areas of scientific research and have important applications in a wide variety of fields. The data suggest that in the future workers and consumers exposed to nanoparticles will significantly increase.Dermal absorption and toxicity of nanoparticlesAt now there are gaps in understanding about the human and environmental risk that manufactured nanoparticles pose for occupational exposed people and for consumers. There is a need for assessing the health and environmental impacts, the nanoparticles life cycle, the human exposure routes, the behavior of nanoparticles in the body, and the risk for workers. Possible routes of entry into the body include inhalation, absorption through the skin or digestive tract, injection, and absorption or implantation for drugs delivery systems. In particular, dermal absorption and skin penetration of nanoparticles needs a better evaluation because few and contradictory data are present in the literature, mainly on titanium dioxide.ConclusionsThere are limited data on carbon-based nanoparticles and very few data on other metal nanoparticles increasingly used in industry. The article reviews the literature on the percutaneous absorption of nanoparticles and their effect on skin.

Human skin penetration of gold nanoparticles through intact and damaged skin.

Abstract Gold nanoparticles (AuNPs) are produced for many applications but there is a lack of available data on their skin absorption. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. A physiological solution was used as receiving phase and 0.5 mL (1st exp) and 1.5 mL (2nd exp) of a solution containing 100 mgL-1 of AuNPs (15 and 45 μg cm-2, respectively) was applied as donor phase to the outer surface of the skin for 24 h. Skin absorption was dose dependent. Mean gold content of 214.0 ± 43.7 ng cm-2 and 187.7 ± 50.2 ng cm-2 were found in the receiving solutions of cells where the AuNPs solution was applied in higher concentration on intact skin (8 Franz cells) and on damaged skin (8 Franz cells), respectively. Twenty-four hours gold flux permeation was 7.8 ± 2.0 ng cm-2 h-1 and 7.1 ± 2.5 ng cm-2 h-1 in intact and damaged skin, respectively, with a lag time less than 1 hour. Transmission Electron Microscope analysis on skin samples and chemical analysis using Inductively Coupled Plasma-Mass Spectrometry demonstrated the presence of AuNPs into epidermis and dermis. This study showed that AuNPs are able to penetrate the human skin in an in vitro diffusion cell system.

In vitro absorption of metal powders through intact and damaged human skin.

The bioavailability of metals, which are known as important contact allergens, is decisive for the development and the maintenance of contact dermatitis. The aim of this study was to evaluate the percutaneous penetration of metal powders of cobalt (Co), nickel (Ni) and chromium (Cr) and the effect of skin lesions on skin absorption. In vitro permeation experiments were performed using the Franz diffusion cells with intact and damaged human skin. Physiological solution was used as receiving phase and metal powders (Co, Ni and Cr) dispersed in synthetic sweat at pH 4.5 were applied as donor phase to the outer surface of the skin for 24h. The amount of each metal permeating the skin was analysed by electro-thermal atomic absorption spectroscopy (ETAAS). Donor solution analysis demonstrated that metals were present as ions. Measurements of metals skin content were also exploited. Median Co and Ni concentrations found in the receiving phase were significantly higher when Co and Ni powders were applied on the abraded skin than after application on the intact skin (3566 and 2631ngcm(-2) vs. 8.4 and 31ngcm(-2), respectively). No significant difference was found in Cr permeation through intact and damaged skin. The measurement of metals skin content showed that Co, Ni and Cr concentrations were significantly higher in the damaged skin than in the intact skin. Co and Ni ions concentrations increased significantly when the donor solutions were applied on the damaged skin, while Cr ions concentrations did not increase. This study demonstrated that Co and Ni powders can permeate through damaged skin more easily than Cr powder, which has probably a stronger skin proteins binding capacity. Therefore, our results suggest that is necessary to prevent skin contamination when using toxic substances because a small injury to the skin barrier can significantly increase skin absorption.

Skin absorption of inorganic lead (PbO) and the effect of skin cleansers.

Objective: The aim of this study was to investigate the percutaneous penetration of lead oxide (PbO) powder and the effect of rapid skin decontamination with two different detergents. Methods: Franz cells were used to study in vitro PbO skin penetration through human skin during a 24-hour period. The tests were performed without or with decontamination using either Ivory Liquid soap or a new experimental cleanser 30 minutes after the start of exposure. Results: We confirm that PbO can pass through the skin with a median penetration of 2.9 ng/cm2 (25–75th percentiles 0.35–6). The cleaning procedure using Ivory Liquid soap significantly increased skin penetration with a median value of 23.6 ng/cm2 (25–75th percentiles 12–47.1; Mann-Whitney U test, P = 0.0002), whereas the new experimental cleanser only marginally increased penetration (7.1 ng/cm2). Conclusions: Our results indicate that it is necessary to prevent skin contamination from occurring because a short contact can increase skin content and penetration even if quickly followed by washing. This study demonstrated that PbO powder can pass through the skin and that skin decontamination done after 30 minutes of exposure did not decrease skin absorption occurring over 24 hours and stresses the need to prevent skin contamination when using toxic substances.

Associations between two job stress models and measures of salivary cortisol

PurposeTo investigate the association between two job stress models—the job demand-control model and the effort-reward imbalance model—and repeated measures of salivary cortisol among male and female call-centre operators.MethodsDaily cortisol profiles consisting of seven time points were measured across two workdays and one leisure day to determine the cortisol awakening response and the cortisol output in the day in 104 volunteers. The employees completed two self-administered questionnaire—the Karasek’s demand-control questionnaire and the Siegrist’s effort-reward imbalance questionnaire—to assess psychosocial hazards at work. The relations between the perceived workload measures and salivary cortisol levels were analyzed by means of generalized estimating equations method after adjusting for potential confounders (gender, age, educational level, marital status, morning awakening time, sleep duration and quality, weekdays, work schedule, adherence to sampling procedure).ResultsThe total cortisol amount excreted in the awakening period was positively associated with the job strain measures (high strain vs. low strain: 1.4 (2.4–0.3) nmol/l). In contrast, individuals scoring higher in effort-reward imbalance at work had both lower cortisol awakening response (high imbalance vs. low imbalance: −0.7 (−1.3 to −0.2) nmol/l) and lower diurnal secretory activity (−9.2 (−17.7 to −0.7) nmol/l). Gender, weekday and adherence to sampling schedule significantly influenced the cortisol excretion in the morning period.ConclusionsOur results indicate that the two work stress models differentially affect salivary cortisol output. This finding suggests that combining the information from two complementary job stress models results in improved knowledge on the psychobiological correlates of the psychosocial work environment.

Drug delivery nanoparticles in skin cancers.

Nanotechnology involves the engineering of functional systems at nanoscale, thus being attractive for disciplines ranging from materials science to biomedicine. One of the most active research areas of the nanotechnology is nanomedicine, which applies nanotechnology to highly specific medical interventions for prevention, diagnosis, and treatment of diseases, including cancer disease. Over the past two decades, the rapid developments in nanotechnology have allowed the incorporation of multiple therapeutic, sensing, and targeting agents into nanoparticles, for detection, prevention, and treatment of cancer diseases. Nanoparticles offer many advantages as drug carrier systems since they can improve the solubility of poorly water-soluble drugs, modify pharmacokinetics, increase drug half-life by reducing immunogenicity, improve bioavailability, and diminish drug metabolism. They can also enable a tunable release of therapeutic compounds and the simultaneous delivery of two or more drugs for combination therapy. In this review, we discuss the recent advances in the use of different types of nanoparticles for systemic and topical drug delivery in the treatment of skin cancer. In particular, the progress in the treatment with nanocarriers of basal cell carcinoma, squamous cell carcinoma, and melanoma has been reported.

Salivary Cortisol and Psychosocial Hazards at Work

BACKGROUND Experimental and clinical evidence suggest that stress can lead to ill-health through the disregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Studies to date have produced equivocal results likely due to different methodologies and failure to account for confounding factors. This investigation aimed to assess the relation between self-reported work-related stressors and salivary cortisol and to clarify the role of the potential confounders. METHODS Thirty-six call-handlers completed a self-administered job content questionnaire and collected seven daily salivary samples on two workdays and a weekend. The diurnal salivary cortisol output was expressed as cortisol awakening response (CAR), and cortisol output in the rest of the day. Salivary cortisol data were normalized by means of square root transformation. The generalized estimating equations method was used to assess the relation between job strain and cortisol levels after adjusting for gender, weekdays and adherence to the sampling schedule. RESULTS Job strain significantly influenced the total amount of cortisol response to waking (high strain vs. low strain: 1.1 (0.3-2.0) nmol/L). The cortisol response to waking showed gender-specific differences [women excreting greater cortisol than men: 1.1 (0.3-1.9) nmol/L], and weekday differences [workdays vs. weekend: 1.0 (0.3-1.6) nmol/L]. Non-compliance with the sampling protocol was associated with lower salivary cortisol than in adherent subjects. CONCLUSIONS Our results provide further evidence for the HPA axis involvement in the physiological response to work stress. The measure of the CAR showed to be the sensitive index to assess the physiological response to psychosocial factors. Gender, weekday, and protocol compliance were confounding factors.

In vitro study of manganese-doped bioactive glasses for bone regeneration.

A glass belonging to the system SiO2-P2O5-CaO-MgO-Na2O-K2O was modified by introducing two different amounts of manganese oxide (MnO). Mn-doped glasses were prepared by melt and quenching technique and characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) observation and energy dispersion spectrometry (EDS) analysis. In vitro bioactivity test in simulated body fluid (SBF) showed a slight decrease in the reactivity kinetics of Mn-doped glasses compared to the glass used as control; however the glasses maintained a good degree of bioactivity. Mn-leaching test in SBF and minimum essential medium (MEM) revealed fluctuating trends probably due to a re-precipitation of Mn compounds during the bioactivity process. Cellular tests showed that all the Mn-doped glasses, up to a concentration of 50 μg/cm(2) (μg of glass powders/cm(2) of cell monolayer), did not produce cytotoxic effects on human MG-63 osteoblasts cultured for up to 5 days. Finally, biocompatibility tests demonstrated a good osteoblast proliferation and spreading on Mn-doped glasses and most of all that the Mn-doping can promote the expression of alkaline phosphatase (ALP) and some bone morphogenetic proteins (BMPs).

Synthesis and characterisation of bioactive and antibacterial glass–ceramic Part 1 – Microstructure, properties and biological behaviour

Abstract A glass–ceramic composition has been studied to realise a highly bioactive material, suitable for stimulate the bone regeneration, which has been subjected to a patented ion exchange process with silver ions, to impart antibacterial properties. The obtained material has been characterised by SEM, EDS and XRD analyses, before and after the introduction of Ag+ ions, and has been subjected to mechanical tests. Ag+ release was verified by GF-AAS analysis. The influence of silver on material wettability and bioactivity was evaluated through contact angle measurements and in vitro test on SBF solution. Finally, biocompatibility with osteoblast like cells and antibacterial test on Staphylococcus Aureus, have been realised to demonstrate the effective antimicrobial behaviour and the safety of silver doped glass–ceramic. On the basis of this study, it was evinced that ion exchange technique, optimised on glasses in previous research works, allows the controlled introduction of Ag+ ions and can be transferred on medical devices totally or partially realised with bioactive glass–ceramic.