Thermometric absorption spectroscopy through active locking of microbubble resonators

We implemented a Microbubble Resonator (MBRs) as an opto-thermal transducer to reconstruct the absorption spectrum of a nanoparticle suspension through its temperature increase. The experimental configuration features the MBR as both the vial containing the suspension and the optical transducer, allowing for a sensitive ultra-compact system with a straightforward microfluidic integration. With respect to a previous publication, the active lock of the MBR resonance produced an order-of-magnitude improvement in the system performance and a smooth absorption reconstruction. Additionally, since the detection process is temperature-based, the measurement is intrinsically insensitive towards scattering spectrum, both of the particles and of the host liquid. These features make the MBR system an interesting candidate for the characterisation of extremely small samples in the context of medical diagnosis from whole biological samples, quality controls for food safety or chemical production processes, and, in general, for the measurement of absorption in opaque mediums

Identificazione di pattern di espressione genica della displasia renale associata ad uropatia malformativa

Normal kidney and urinary tract development is a complex process, regulated by a strict space-time-corrected sequential activation of a cascade of genes encoding transcription factors, growth factors, cell death/proliferation factors and adhesion molecules. An alteration disrupting this sequential gene expression may cause a defective ureteric bud-to-metanephric mesenchyme cross-talk that results in a renal and urinary tract developmental abnormality (congenital anomalies of kidney and urinary tract - CAKUT). Phenotype severity depends on the stage of nephrogenesis in which the alteration of the developmental program occurs, thus renal dysplasia is the most severe manifestation. However, little is known about CAKUT pathogenesis. The recent advent of microarray technology provided an unique tool to identify genes potentially involved in the pathogenesis of several diseases. During the first stage of this research, we applied the microarray technique to study gene expression profiles of primary renal cell cultures, using an array composed by 21329 oligonucleotides. The aim was to identify potential biomarkers of renal dysplasia. Four genes seemed to be more interesting (UPK1B, SOX11, SPRY1, MMP2). We analysed the expression of these four genes using Real Time PCR on RNA extracted from renal tissue samples of 10 patients with a histological picture of renal dysplasia and 10 with histologically normal renal tissue. Mutation analysis of SPRY1 gene, whose murine homologue is hugely involved in the regulation of GDNF growth factor's expression during ureteric branching, was carried out on 27 patients with renal duplicity. Mutation analysis identified 2 new genomic variants - whose frequency was analysed in a control population - that may be "genomic variants involved in splicing" (SpaGVs). Our research results allow to hypothesize that SPRY1 gene may be involved in the pathogenesis of kidney and urinary tract developmental diseases

Polylysine as a functional biopolymer to couple gold nanorods to tumor-tropic cells

Abstract Background The delivery of plasmonic particles, such as gold nanorods, to the tumor microenvironment has attracted much interest in biomedical optics for topical applications as the photoacoustic imaging and photothermal ablation of cancer. However, the systemic injection of free particles still crashes into a complexity of biological barriers, such as the reticuloendothelial system, that prevent their efficient biodistribution. In this context, the notion to exploit the inherent features of tumor-tropic cells for the creation of a Trojan horse is emerging as a plausible alternative. Results We report on a convenient approach to load cationic gold nanorods into murine macrophages that exhibit chemotactic sensitivity to track gradients of inflammatory stimuli. In particular, we compare a new model of poly-l-lysine-coated particles against two alternatives of cationic moieties that we have presented elsewhere, i.e. a small quaternary ammonium compound and an arginine-rich cell-penetrating peptide. Murine macrophages that are exposed to poly-l-lysine-coated gold nanorods at a dosage of 400 µM Au for 24 h undertake efficient uptake, i.e. around 3 pg Au per cell, retain the majority of their cargo until 24 h post-treatment and maintain around 90% of their pristine viability, chemotactic and pro-inflammatory functions. Conclusions With respect to previous models of cationic coatings, poly-l-lysine is a competitive solution for the preparation of biological vehicles of gold nanorods, especially for applications that may require longer life span of the Trojan horse, say in the order of 24 h. This biopolymer combines the cost-effectiveness of small molecules and biocompatibility and efficiency of natural peptides and thus holds potential for translational developments

Different approaches for the detection of thrombin by an electrochemical aptamer-based assay coupled to magnetic beads

Different assay formats based on the coupling of magnetic beads with electrochemical transduction were compared here for the detection of thrombin by using a thrombin specific aptamer. By using the thrombin-binding aptamer, a direct and an indirect competitive assay for thrombin have been developed by immobilising the aptamer or the protein, respectively. Moreover, another strategy was based on the direct measurement of the enzymatic product of thrombin captured by the immobilised aptamer. All the assays were developed by coupling the electrochemical transduction with the innovative and advantageous use of magnetic beads. The assays based on the immobilisation of the protein were not successful since no binding was recorded between thrombin and its aptamer. With the direct competitive assay, when the aptamer was immobilised onto the magnetic beads, a detection limit of 430 nM for thrombin was achieved. A lower detection limit for the protein (175 nM) was instead obtained by detecting the product of the enzymatic reaction catalysed by thrombin. All these assays were finally compared with a sandwich assay which reached a detection limit of 0.45 nM of thrombin demonstrating the best analytical performances. With this comparison the importance of a deep study on the different analytical approaches for thrombin detection to reach the performances of the best assay configuration has been demonstrated.Fil: Centi, Sonia. Università degli Studi di Firenze; ItaliaFil: Messina, Germán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentina. Università degli Studi di Firenze; ItaliaFil: Trombelli, Sara. Università degli Studi di Firenze; ItaliaFil: Palchetti, Ilaria. Università degli Studi di Firenze; ItaliaFil: Mascini, Marco. Università degli Studi di Firenze; Itali

MOESM1 of Polylysine as a functional biopolymer to couple gold nanorods to tumor-tropic cells

Additional file 1. Additional figures

Photostability of Contrast Agents for Photoacoustics: The Case of Gold Nanorods

Plasmonic particles as gold nanorods have emerged as powerful contrast agents for critical applications as the photoacoustic imaging and photothermal ablation of cancer. However, their unique efficiency of photothermal conversion may turn into a practical disadvantage, and expose them to the risk of overheating and irreversible photodamage. Here, we outline the main ideas behind the technology of photoacoustic imaging and the use of relevant contrast agents, with a main focus on gold nanorods. We delve into the processes of premelting and reshaping of gold nanorods under illumination with optical pulses of a typical duration in the order of few ns, and we present different approaches to mitigate this issue. We undertake a retrospective classification of such approaches according to their underlying, often implicit, principles as: constraining the initial shape; or speeding up their thermal coupling to the environment by lowering their interfacial thermal resistance; or redistributing the input energy among more particles. We discuss advantages, disadvantages and contexts of practical interest where one solution may be more appropriate than the other

mRNA sequencing of a novel NPHS2 intronic mutation in a child with focal and segmental glomerulosclerosis

The NPHS2 gene encodes podocin, a membrane protein that acts as the structural scaffold in podocyte foot processes. NPHS2 mutations are associated with steroid-resistant neph-rotic syndrome (SRNS), with the pathologic variant being focal and segmental glomerulosclerosis (FSGS), an emerging cause of end-stage renal disease in children. We describe a novel NPHS2 sequence variant in a girl with SRNS. Onset occurred at the age of seven years, with edema, hypo-proteinemia, hypoalbuminemia, hypercholesterolemia, hypertriglyceridemia and nephrotic protei-nuria. Renal function was normal and autoimmunity markers were negative. Proteinuria failed to decrease after standard steroid therapy. Renal biopsy showed FSGS. Cyclosporine therapy was instituted, but no remission of proteinuria was achieved and chronic renal failure developed. Mole-cular analysis of the NPHS2 gene revealed a homozygous nucleotide substitution in position c.451+3A>T in intron 3-4. This nucleotide substitution has not been reported in the literature till date. The effect of the detected substitution on podocin protein was demonstrated by renal biopsy RNA extraction and cDNA amplification analysis. This technique had never been applied to a NPHS2 mutation. Based on these results, immunosuppressive drugs were discontinued and conser-vative therapy was undertaken