Magnetic Resonance Imaging Evidence Supporting the Efficacy of Cladribine Tablets in the Treatment of Relapsing-Remitting Multiple Sclerosis.

Numerous therapies are currently available to modify the disease course of multiple sclerosis (MS). Magnetic resonance imaging (MRI) plays a pivotal role in assessing treatment response by providing insights into disease activity and clinical progression. Integrating MRI findings with clinical and laboratory data enables a comprehensive assessment of the disease course. Among available MS treatments, cladribine is emerging as a promising option due to its role as a selective immune reconstitution therapy, with a notable impact on B cells and a lesser effect on T cells. This work emphasizes the assessment of MRI's contribution to MS treatment, particularly focusing on the influence of cladribine tablets on imaging outcomes, encompassing data from pivotal and real-world studies. The evidence highlights that cladribine, compared with placebo, not only exhibits a reduction in inflammatory imaging markers, such as T1-Gd+, T2 and combined unique active (CUA) lesions, but also mitigates the effect on brain volume loss, particularly within grey matter. Importantly, cladribine reveals early action by reducing CUA lesions within the first months of treatment, regardless of a patient's initial conditions. The selective mechanism of action, and sustained efficacy beyond year 2, combined with its early onset of action, collectively position cladribine tablets as a pivotal component in the therapeutic paradigm for MS. Overall, MRI, along with clinical measures, has played a substantial role in showcasing the effectiveness of cladribine in addressing both the inflammatory and neurodegenerative aspects of MS.

Reversal of neurological deficits by painless nerve growth factor in a mouse model of Rett syndrome.

Rett syndrome is a rare genetic neurodevelopmental disease, affecting 1 in over 10 000 females born worldwide, caused by de novo mutations in the X-chromosome-located methyl-CpG-binding protein 2 (MeCP2) gene. Despite the great effort put forth by the scientific community, a therapy for this devastating disease is still needed. Here, we tested the therapeutic effects of a painless mutein of the nerve growth factor (NGF), called human NGF painless (hNGFp), via a non-invasive intranasal delivery in female MeCP2+/- mice. Of note, previous work had demonstrated a broad biodistribution of hNGFp in the mouse brain by the nasal delivery route. We report that (i) the long-term lifelong treatment of MeCP2+/- mice with hNGFp, starting at 2 months of age, increased the chance of survival while also greatly improving behavioural parameters. Furthermore, when we assessed the phenotypic changes brought forth by (ii) a short-term 1-month-long hNGFp-treatment, starting at 3 months of age (right after the initial presentation of symptoms), we observed the rescue of a well known neuronal target population of NGF, cholinergic neurons in the medial septum. Moreover, we reveal a deficit in microglial morphology in MeCP2+/- mice, completely reversed in treated animals. This effect on microglia is in line with reports showing microglia to be a TrkA-dependent non-neuronal target cell population of NGF in the brain. To understand the immunomodulatory activity of hNGFp, we analysed the cytokine profile after hNGFp treatment in MeCP2+/- mice, to discover that the treatment recovered the altered expression of key neuroimmune-communication molecules, such as fractalkine. The overall conclusion is that hNGFp delivered intranasally can ameliorate symptoms in the MeCP2+/- model of Rett syndrome, by exerting strong neuroprotection with a dual mechanism of action: directly on target neurons and indirectly via microglia.

Use of Active Learning During Emergency Remote Teaching in COVID-19 Pandemic.

The mandatory isolation caused by COVID-19 required the adoption of emergency remote teaching, which caused difficulties for instructors, especially for those who use active learning that depends on student participation in class. This study aimed to investigate the ability of instructors to apply active learning effectively given the pandemic context. This was a cross-sectional observational study carried out in an undergraduate medical school. The sample was composed from one to three classes of 28 instructors that were observed synchronously. Each class was analyzed using a form created from an adaptation of the PORTAAL tool, aiming to evaluate quantitatively essential elements for active learning. We observed that the mean times devoted to activities and active participation of students were 54.8% and 33.1% of the total class time, respectively. Among the time spent in student interactions, the intra-group demanded the highest percentage of the class time. Additionally, 22.0% of the activities presented a high level in Bloom's taxonomy and there was a positive correlation between the percentage of activities at higher Bloom levels and the percentage of class time with student participation, intra-group or between-group interactions, supporting the use of higher-order cognitive skills in a collaborative and student-centered context. In conclusion, our findings indicate that some instructors were able to apply essential elements for an active and collaborative learning even during the emergency remote teaching.

Sports activity limitation during the COVID-19 pandemic in young Italian athletes: impact on mental health in children, adolescents, and young adults.

Introduction: The closure of sports centres was implemented as a preventive measure to mitigate the transmission of SARS-CoV-2. Given the observed global decline in physical activity and concurrent rise in sedentary behaviour, even among younger age groups, a retrospective cross-sectional study was undertaken to evaluate the effects of this measure on mental health in children, adolescents, and young adults during the initial phases of the COVID-19 pandemic. Methods: A total of 1,717 non-professional athletes (age range: 6-25; 53.9% males, 44.6% females) completed an online questionnaire including widely used and validated measures for mental health assessment (SDQ and PGWB-S) and questions regarding sociodemographic characteristics (such as gender), physical activity, and screen time. The association between mental health and sociodemographic characteristics, physical activity, and screen time was evaluated by using univariate and multivariable logistic regression models. Results: In children and adolescents, the incidence of psychological difficulties was associated with not being physically active (OR = 1.49; 95% CI: 1.09, 2.07; p = 0.015). Engaging in physical activity during the period of closures, particularly if more than twice a week, was significantly associated with less psychological difficulties for children/adolescents (OR = 0.54; 95% CI: 0.35, 0.82; p = 0.004) and psychological symptoms (i.e., psychological well-being lower than the median) for youth/young adults (OR = 0.25; 95% CI: 0.14, 0.45; p < 0.001). More psychological difficulties were also found in males for children and adolescents (OR = 1.37; 95% CI: 1.06, 1.79; p = 0.018). However, young adult males showed less psychological symptoms than females (OR = 0.35; 95% CI: 0.22, 0.55; p = 0.001). Additionally, a greater amount of screen time was associated with a higher incidence of psychological symptoms in the whole sample. Conclusions: Our results confirm the positive impact of physical activity on mental health during the COVID-19 pandemic among younger age groups. They also provide valuable insights into the risk-benefit relationship of interrupting sports activities as a preventive measure for infectious diseases.

Reduced levels of NGF shift astrocytes toward a neurotoxic phenotype.

Nerve growth factor (NGF) is critical for neuronal physiology during development and adulthood. Despite the well-recognized effect of NGF on neurons, less is known about whether NGF can actually affect other cell types in the central nervous system (CNS). In this work, we show that astrocytes are susceptible to changes in ambient levels of NGF. First, we observe that interfering with NGF signaling in vivo via the constitutive expression of an antiNGF antibody induces astrocytic atrophy. A similar asthenic phenotype is encountered in an uncleavable proNGF transgenic mouse model (TgproNGF#72), effectively increasing the brain proNGF levels. To examine whether this effect on astrocytes is cell-autonomous, we cultured wild-type primary astrocytes in the presence of antiNGF antibodies, uncovering that a short incubation period is sufficient to potently and rapidly trigger calcium oscillations. Acute induction of calcium oscillations by antiNGF antibodies is followed by progressive morphological changes similar to those observed in antiNGF AD11 mice. Conversely, incubation with mature NGF has no effect on either calcium activity nor on astrocytic morphology. At longer timescales, transcriptomic analysis revealed that NGF-deprived astrocytes acquire a proinflammatory profile. In particular, antiNGF-treated astrocytes show upregulation of neurotoxic transcripts and downregulation of neuroprotective mRNAs. Consistent with that data, culturing wild-type neurons in the presence of NGF-deprived astrocytes leads to neuronal cell death. Finally, we report that in both awake and anesthetized mice, astrocytes in layer I of the motor cortex respond with an increase in calcium activity to acute NGF inhibition using either NGF-neutralizing antibodies or a TrkA-Fc NGF scavenger. Moreover, in vivo calcium imaging in the cortex of the 5xFAD neurodegeneration mouse model shows an increased level of spontaneous calcium activity in astrocytes, which is significantly reduced after acute administration of NGF. In conclusion, we unveil a novel neurotoxic mechanism driven by astrocytes, triggered by their sensing and reacting to changes in the levels of ambient NGF.

Human TrkAR649W mutation impairs nociception, sweating and cognitive abilities: a mouse model of HSAN IV.

A functional nerve growth factor NGF-Tropomyosin Receptor kinase A (TrkA) system is an essential requisite for the generation and maintenance of long-lasting thermal and mechanical hyperalgesia in adult mammals. Indeed, mutations in the gene encoding for TrkA are responsible for a rare condition, named Hereditary Sensory and Autonomic Neuropathy type IV (HSAN IV), characterized by the loss of response to noxious stimuli, anhidrosis and cognitive impairment. However, to date, there is no available mouse model to properly understand how the NGF-TrkA system can lead to pathological phenotypes that are distinctive of HSAN IV. Here, we report the generation of a knock-in mouse line carrying the HSAN IV TrkAR649W mutation. First, by in vitro biochemical and biophysical analyses, we show that the pathological R649W mutation leads to kinase-inactive TrkA also affecting its membrane dynamics and trafficking. In agreement with the HSAN IV human phenotype, TrkAR649W/m mice display a lower response to thermal and chemical noxious stimuli, correlating with reduced skin innervation, in addition to decreased sweating in comparison to TrkAh/m controls. Moreover, the R649W mutation decreases anxiety-like behavior and compromises cognitive abilities, by impairing spatial-working and social memory. Our results further uncover unexplored roles of TrkA in thermoregulation and sociability. In addition to accurately recapitulating the clinical manifestations of HSAN IV patients, our findings contribute to clarifying the involvement of the NGF-TrkA system in pain sensation.

The Impact of Sport Activity Shut down during the COVID-19 Pandemic on Children, Adolescents, and Young Adults: Was It Worthwhile?

We conducted a national retrospective survey of 1764 athletes aged ≤25 years to investigate the benefit-risk balance of sport closure during the COVID-19 pandemic peaks in Italy. Univariate and multivariable analyses were carried out to investigate the association between sport practice during the study period and (1) the risk of SARS-CoV-2 infection in athletes and their families and (2) body mass index (BMI) change, and adherence to World Health Organization (WHO) guidelines for physical activity. The percentage of subjects with a positive SARS-CoV-2 test was similar in those participating and not taking part into sport activities (11% vs. 12%, respectively, p = 0.31). Restricting the analysis to subjects who practiced sports within an organized sport society/center, the risk of SARS-CoV-2 positivity was reduced for athletes who had never stopped their training (odds ratio (OR); 95% confidence intervals (CI): 0.62; 0.41-0.93). On the other side, responders who had stopped sport activity showed a 1% increase in BMI. Adherence to WHO guidelines for physical activity was significantly higher for athletes who had continued sport activities. In conclusion, sport closure and limitations had an important negative impact on the overall health of young athletes, being also not effective in reducing the spread of COVID-19.

Disentangling the signaling complexity of nerve growth factor receptors by CRISPR/Cas9.

The binding of nerve growth factor (NGF) to the tropomyosin-related kinase A (TrkA) and p75NTR receptors activates a large variety of pathways regulating critical processes as diverse as proliferation, differentiation, membrane potential, synaptic plasticity, and pain. To ascertain the details of TrkA-p75NTR interaction and cooperation, a plethora of experiments, mostly based on receptor overexpression or downregulation, have been performed. Among the heterogeneous cellular systems used for studying NGF signaling, the PC12 pheochromocytoma-derived cell line is a widely used model. By means of CRISPR/Cas9 genome editing, we created PC12 cells lacking TrkA, p75NTR , or both. We found that TrkA-null cells become unresponsive to NGF. Conversely, the absence of p75NTR enhances the phosphorylation of TrkA and its effectors. Using a patch-clamp, we demonstrated that the individual activation of TrkA and p75NTR by NGF results in antagonizing effects on the membrane potential. These newly developed PC12 cell lines can be used to investigate the specific roles of TrkA and p75NTR in a genetically defined cellular model, thus providing a useful platform for future studies and further gene editing.

Reduced ccl11/eotaxin mediates the beneficial effects of environmental stimulation on the aged hippocampus.

A deterioration in cognitive performance accompanies brain aging, even in the absence of neurodegenerative pathologies. However, the rate of cognitive decline can be slowed down by enhanced cognitive and sensorimotor stimulation protocols, such as environmental enrichment (EE). Understanding how EE exerts its beneficial effects on the aged brain pathophysiology can help in identifying new therapeutic targets. In this regard, the inflammatory chemokine ccl11/eotaxin-1 is a marker of aging with a strong relevance for neurodegenerative processes. Here, we demonstrate that EE in both elderly humans and aged mice decreases circulating levels of ccl11. Interfering, in mice, with the ccl11 decrease induced by EE ablated the beneficial effects on long-term memory retention, hippocampal neurogenesis, activation of local microglia and of ribosomal protein S6. On the other hand, treatment of standard-reared aged mice with an anti-ccl11 antibody resulted in EE-like improvements in spatial memory, hippocampal neurogenesis, and microglial activation. Taken together, our findings point to a decrease in circulating ccl11 concentration as a key mediator of the enhanced hippocampal function resulting from exposure to EE.

Understanding pain perception through genetic painlessness diseases: The role of NGF and proNGF.

Nerve growth factor (NGF), by binding to TrkA and p75NTR receptors, regulates the survival and differentiation of sensory neurons during development and mediates pain transmission and perception during adulthood, by acting at different levels of the nervous system. Key to understanding the role of NGF as a pain mediator is the finding that mutations (namely, R121W, V232fs and R221W) in the NGF gene cause painlessness disease Hereditary Sensory and Autonomic Neuropathy type V (HSAN V). Here we shall review the consequences of these NGF mutations, each of which results in specific clinical signs: R221W determines congenital pain insensitivity with no overt cognitive disabilities, whereas V232fs and R121W also result in intellectual disability, thus showing similarities to HSAN IV, which is caused by mutations in TrkA, rather than to HSAN V. Comparing the cellular, biochemical and clinical findings of these mutations could help in better understanding not only the possible mechanisms underlying HSAN V, but also mechanisms of NGF signalling and roles. These mutations alter the balance between NGF and proNGF in favour of an accumulation of the latter, suggesting a possible role of proNGF as a molecule with an analgesic role. Furthermore, the neurotrophic and pronociceptive functions of NGF are split by the R221W mutation, making NGF variants based on this mutation interesting for designing therapeutic applications for many diseases. This review emphasizes the possibility of using the mutations involved in "painlessness" clinical disorders as an innovative approach to identify new proteins and pathways involved in pain transmission and perception. OUTSTANDING QUESTIONS: Why do homozygous HSAN V die postnatally? What is the cause of this early postnatal lethality? Is the development of a mouse or a human feeling less pain affecting higher cognitive and perceptual functions? What is the consequence of the HSAN V mutation on the development of joints and bones? Are the multiple fractures observed in HSAN V patients due exclusively to the carelessness consequent to not feeling pain, or also to an intrinsic frailty of their bones? Are heterodimers of NGFWT and NGFR221W in the heterozygote state formed? And if so, what are the properties of these heterodimeric proteins? How is the processing of proNGFR221W to NGFR221W affected by the mutation?

The Stemness Gene Mex3A Is a Key Regulator of Neuroblast Proliferation During Neurogenesis.

Mex3A is an RNA binding protein that can also act as an E3 ubiquitin ligase to control gene expression at the post-transcriptional level. In intestinal adult stem cells, MEX3A is required for cell self-renewal and when overexpressed, MEX3A can contribute to support the proliferation of different cancer cell types. In a completely different context, we found mex3A among the genes expressed in neurogenic niches of the embryonic and adult fish brain and, notably, its expression was downregulated during brain aging. The role of mex3A during embryonic and adult neurogenesis in tetrapods is still unknown. Here, we showed that mex3A is expressed in the proliferative region of the developing brain in both Xenopus and mouse embryos. Using gain and loss of gene function approaches, we showed that, in Xenopus embryos, mex3A is required for neuroblast proliferation and its depletion reduced the neuroblast pool, leading to microcephaly. The tissue-specific overexpression of mex3A in the developing neural plate enhanced the expression of sox2 and msi-1 keeping neuroblasts into a proliferative state. It is now clear that the stemness property of mex3A, already demonstrated in adult intestinal stem cells and cancer cells, is a key feature of mex3a also in developing brain, opening new lines of investigation to better understand its role during brain aging and brain cancer development.

Graphene Promotes Axon Elongation through Local Stall of Nerve Growth Factor Signaling Endosomes.

Several works reported increased differentiation of neuronal cells grown on graphene; however, the molecular mechanism driving axon elongation on this material has remained elusive. Here, we study the axonal transport of nerve growth factor (NGF), the neurotrophin supporting development of peripheral neurons, as a key player in the time course of axonal elongation of dorsal root ganglion neurons on graphene. We find that graphene drastically reduces the number of retrogradely transported NGF vesicles in favor of a stalled population in the first 2 days of culture, in which the boost of axon elongation is observed. This correlates with a mutual charge redistribution, observed via Raman spectroscopy and electrophysiological recordings. Furthermore, ultrastructural analysis indicates a reduced microtubule distance and an elongated axonal topology. Thus, both electrophysiological and structural effects can account for graphene action on neuron development. Unraveling the molecular players underneath this interplay may open new avenues for axon regeneration applications.

The NGFR100W Mutation Specifically Impairs Nociception without Affecting Cognitive Performance in a Mouse Model of Hereditary Sensory and Autonomic Neuropathy Type V.

Nerve growth factor (NGF) is a key mediator of nociception, acting during the development and differentiation of dorsal root ganglion (DRG) neurons, and on adult DRG neuron sensitization to painful stimuli. NGF also has central actions in the brain, where it regulates the phenotypic maintenance of cholinergic neurons. The physiological function of NGF as a pain mediator is altered in patients with Hereditary Sensory and Autonomic Neuropathy type V (HSAN V), caused by the 661C>T transition in the Ngf gene, resulting in the R100W missense mutation in mature NGF. Homozygous HSAN V patients present with congenital pain insensitivity, but are cognitively normal. This led us to hypothesize that the R100W mutation may differentially affect the central and peripheral actions of NGF. To test this hypothesis and provide a mechanistic basis to the HSAN V phenotype, we generated transgenic mice harboring the human 661C>T mutation in the Ngf gene and studied both males and females. We demonstrate that heterozygous NGFR100W/wt mice display impaired nociception. DRG neurons of NGFR100W/wt mice are morphologically normal, with no alteration in the different DRG subpopulations, whereas skin innervation is reduced. The NGFR100W protein has reduced capability to activate pain-specific signaling, paralleling its reduced ability to induce mechanical allodynia. Surprisingly, however, NGFR100W/wt mice, unlike heterozygous mNGF+/- mice, show no learning or memory deficits, despite a reduction in secretion and brain levels of NGF. The results exclude haploinsufficiency of NGF as a mechanistic cause for heterozygous HSAN V mice and demonstrate a specific effect of the R100W mutation on nociception.SIGNIFICANCE STATEMENT The R100W mutation in nerve growth factor (NGF) causes Hereditary Sensory and Autonomic Neuropathy type V, a rare disease characterized by impaired nociception, even in apparently clinically silent heterozygotes. For the first time, we generated and characterized heterozygous knock-in mice carrying the human R100W-mutated allele (NGFR100W/wt). Mutant mice have normal nociceptor populations, which, however, display decreased activation of pain transduction pathways. NGFR100W interferes with peripheral and central NGF bioavailability, but this does not impact on CNS function, as demonstrated by normal learning and memory, in contrast with heterozygous NGF knock-out mice. Thus, a point mutation allows neurotrophic and pronociceptive functions of NGF to be split, with interesting implications for the treatment of chronic pain.

Cortical Seizures in FoxG1+/- Mice are Accompanied by Akt/S6 Overactivation, Excitation/Inhibition Imbalance and Impaired Synaptic Transmission.

The correct morphofunctional shaping of the cerebral cortex requires a continuous interaction between intrinsic (genes/molecules expressed within the tissue) and extrinsic (e.g., neural activity) factors at all developmental stages. Forkhead Box G1 (FOXG1) is an evolutionarily conserved transcription factor, essential for the cerebral cortex patterning and layering. FOXG1-related disorders, including the congenital form of Rett syndrome, can be caused by deletions, intragenic mutations or duplications. These genetic alterations are associated with a complex phenotypic spectrum, spanning from intellectual disability, microcephaly, to autistic features, and epilepsy. We investigated the functional correlates of dysregulated gene expression by performing electrophysiological assays on FoxG1+/- mice. Local Field Potential (LFP) recordings on freely moving animals detected cortical hyperexcitability. On the other hand, patch-clamp recordings showed a downregulation of spontaneous glutamatergic transmission. These findings were accompanied by overactivation of Akt/S6 signaling. Furthermore, the expression of vesicular glutamate transporter 2 (vGluT2) was increased, whereas the level of the potassium/chloride cotransporter KCC2 was reduced, thus indicating a higher excitation/inhibition ratio. Our findings provide evidence that altered expression of a key gene for cortical development can result in specific alterations in neural circuit function at the macro- and micro-scale, along with dysregulated intracellular signaling and expression of proteins controlling circuit excitability.

A triheptanoin-supplemented diet rescues hippocampal hyperexcitability and seizure susceptibility in FoxG1+/- mice.

The Forkhead Box G1 (FOXG1) gene encodes a transcription factor with an essential role in mammalian telencephalon development. FOXG1-related disorders, caused by deletions, intragenic mutations or duplications, are usually associated with severe intellectual disability, autistic features, and, in 87% of subjects, epileptiform manifestations. In a subset of patients with FoxG1 mutations, seizures remain intractable, prompting the need for novel therapeutic options. To address this issue, we took advantage of a haploinsufficient animal model, the FoxG1+/- mouse. In vivo electrophysiological analyses of FoxG1+/- mice detected hippocampal hyperexcitability, which turned into overt seizures upon delivery of the proconvulsant kainic acid, as confirmed by behavioral observations. These alterations were associated with decreased expression of the chloride transporter KCC2. Next, we tested whether a triheptanoin-based anaplerotic diet could have an impact on the pathological phenotype of FoxG1+/- mice. This manipulation abated altered neural activity and normalized enhanced susceptibility to proconvulsant-induced seizures, in addition to rescuing altered expression of KCC2 and increasing the levels of the GABA transporter vGAT. In conclusion, our data show that FoxG1 haploinsufficiency causes dysfunction of hippocampal circuits and increases the susceptibility to a proconvulsant insult, and that these alterations are rescued by triheptanoin dietary treatment.

Cholinergic striatal neurons are increased in HSAN V homozygous mice despite reduced NGF bioavailability.

The neurotrophin Nerve growth factor (NGF) plays a critical role in the mature and developing nervous system. A point mutation (R100W) in the NGFB gene was found in patients with Hereditary Sensory and Autonomic Neuropathy type V (HSAN V), which leads to pain insensitivity. In a previous work it has been shown that the mutation provokes a reduced secretion of mature NGF. In this study we generated and analyzed homozygous NGFR100W/R100W mice to understand whether the reduced NGF bioavailability can contribute to the clinical phenotype of the homozygous condition. We found that the majority of NGFR100W/R100W mice were born normal but failed to reach the first month of age. This early lethality was rescued by daily treatment with wild type NGF. In addition, we found that the density of cholinergic neurons of homozygous mice was unaffected in the medial septum and in the nucleus basalis of Meynert, whereas, suprisingly, it was increased specifically in the striatum. Due to the known action of the striatal cholinergic tone in modulating pain, our findings support the hypothesis that a central mechanism, linked to the NGFR100W-dependent increase of the striatal cholinergic tone, can contribute to the pain insensitivity observed in HSAN V patients.

Gold nanoparticles functionalized by rhodamine B isothiocyanate: A new tool to control plasmonic effects.

Gold nanoparticles with an average diameter of 10 nm, functionalized by the dye molecule rhodamine B isothiocyanate, have been synthesized. The resulting material has been extensively characterized both chemically, to investigate the bonding between the dye molecules and the nanoparticles, and physically, to understand the details of the aggregation induced by interaction between dye molecules on different nanoparticles. The plasmonic response of the system has been further characterized by measurement and theoretical simulation of the static UV-Vis extinction spectra of the aggregates produced following different synthesis procedures. The model parameters used in the simulation gave further useful information on the aggregation and its relationship to the plasmonic response. Finally, we investigated the time dependence of the plasmonic effects of the nanoparticles and fluorescence of the dye molecule using an ultrafast pump-probe optical method. By modulating the quantity of dye molecules on the surface of the nanoparticles it was possible to exert fine control over the plasmonic response of nanoparticles.

Functionalized gold nanoparticles for topical delivery of methotrexate for the possible treatment of psoriasis.

Gold nanoparticles (AuNPs) represent an effective choice for topical drug delivery systems thanks to their small size, general non-toxicity, ease of functionalization and high surface to volume ratio. Even if systemic, methotrexate still plays an important role in psoriasis treatment: its topical use shows insufficient percutaneus penetration owing to limited passive diffusion, high molecular weight and dissociation at physiological pH. The aim of our study was to design a new drug delivery nanocarrier for Methotrexate and to improve its solubility, stability and biodistribution. AuNPs were on purpose prepared with a hydrophilic stabilizing layer, in order to improve the colloidal stability in water. Water-soluble gold nanoparticles functionalized by sodium 3-mercapto-1-propansulfonate (Au-3MPS) were prepared and loaded with methotrexate (MTX). The loading efficiency of MTX on Au-3MPS was assessed in the range 70-80%, with a fast release (80% in one hour). The release was studied up to 24h reaching the value of 95%. The Au-3MPS@MTX conjugate was fully characterized by spectroscopic techniques (UV-vis, FTIR) and DLS. Preliminary toxicity tests in the presence of keratinocytes monolayers allowed to assess that the used Au-3MPS are not toxic. The conjugate was then topically used on C57BL/6 mouse normal skin in order to trace the absorption behavior. STEM images clearly revealed the distribution of gold nanoparticles inside the cells. In vitro studies showed that Methotrexate conjugated with Au-3MPS is much more efficient than Methotrexate alone. Moreover, DL50, based on MTT analysis, is 20 folds reduced at 48 h, by the presence of nanoparticles conjugation. UV-vis spectra for in vivo tracing of the conjugate on bare mouse skin after 24h of application, show increased delivery of Methotrexate in the epidermis and dermis using Au-3MPS@MTX conjugate, compared to MTX alone. Moreover we observed absence of the Au-3MPS in the dermis and in the epidermis, suggesting that these layers of the skin do not retain the nanoparticles. Based on our data, we found that the novel Au-3MPS@MTX conjugate is an effective non-toxic carrier for the satisfactory percutaneous absorption of Methotrexate and could help in possible topical treatment of psoriasis.

Hydrophilic silver nanoparticles with tunable optical properties: application for the detection of heavy metals in water.

Due their excellent chemo-physical properties and ability to exhibit surface plasmon resonance, silver nanoparticles (AgNPs) have become a material of choice in various applications, such as nanosensors, electronic devices, nanobiotechnology and nanomedicine. In particular, from the environmental monitoring perspective, sensors based on silver nanoparticles are in great demand because of their antibacterial and inexpensive synthetic method. In the present study, we synthesized AgNPs in water phase using silver nitrate as precursor molecules, hydrophilic thiol (3-mercapto-1-propanesulfonic acid sodium salt, 3MPS) and sodium borohydride as capping and reducing agents, respectively. The AgNPs were characterized using techniques such as surface plasmon resonance (SPR) spectroscopy, dynamic light scattering (DLS), zeta potential (ζ-potential) measurements and scanning tunneling microscopy (STM). Further, to demonstrate the environmental application of our AgNPs, we also applied them for heavy metal sensing by detecting visible color modification due to SPR spectral changes. We found that these negatively charged AgNPs show good response to nickel (II) and presented good sensibility properties for the detection of low amount of ions in water in the working range of 1.0-0.1 ppm.

Functionalized platinum nanoparticles with surface charge trigged by pH: synthesis, characterization and stability studies.

In this work, the synthesis and characterization of functionalized platinum nanoparticles (PtNPs) have been investigated. PtNPs were obtained by a wet redox procedure using 2-diethylaminoethanethiol hydrochloride (DEA) as capping agent. By varying the Pt/thiol molar ratio, monodispersed and stable particles with diameters in the range of 3-40 nm were isolated. The amino functionality allows neutral particles to be obtained in basic water solution and positive charged nanoparticles in neutral or acidic water solution (pH 7-2), as confirmed by DLS and ζ-potential measurements. FTIR spectroscopy, FE-SEM, DLS and ζ-potential measurements confirmed the size and showed long term water stability (up to three months) of the colloidal system.