Rational design of gold nanoparticles functionalized with carboranes for application in Boron Neutron Capture Therapy

In this paper we propose a bottom-up approach to obtain new boron carriers built with ortho-carborane functionalized gold nanoparticles (GNPs) for applications in Boron Neutron Capture Therapy. The interaction between carboranes and the gold surface was assured by one or two SH-groups directly linked to the boron atoms of the B10C2 cage. This allowed obtaining stable, non toxic systems, though optimal biological performance was hampered by low solubility in aqueous media. To improve cell uptake, the hydrophilic character of carborane functionalized GNPs was enhanced by further coverage with an appropriately tailored diblock copolymer (PEO-b-PCL). This polymer also contained pendant carboranes to provide anchoring to the pre-functionalized GNPs. In vitro tests, carried out on osteosarcoma cells, showed that the final vectors possessed excellent biocompatibility joint to the capacity of concentrating boron atoms in the target, which is encouraging evidenced to pursue applications in vivo

An improved neutron autoradiography set-up, applied to 10B concentration measurements for biological samples

The development of a new 10B delivery system, with higher selectivity for the tumor with respect to clinically used sodium borocaptate (BSH) and boronophenylalanine (BPA), underlies future improvements in clinical outcomes of Boron Neutron Capture Therapy. A 10B concentration measuring technique for biological samples is needed in order to evaluate the performance of the new boronated formulations. At the Triga Mark II nuclear facility in Pavia, two techniques have been set-up: Alpha Spectrometry (AS) [1] and Quantitative Neutron Capture Radiography (QNCR) [2]. The latter has been recently improved, to ensure a higher accuracy and an optimized efficiency when a high number of samples is analyzed. In the first QNCR set-up, described by M.A Gadan et al. [2] a suitable calibration curve and a sufficient resolution were achieved; however, there were still margin for improvements. Firstly it was necessary to reduce the timing of the overall procedure, caused by an etching time longer than 2 hours. Secondly, in order to reduce the background, only the tracks due to 7Li and α ions had to be visualized. The second condition would simplify the data acquisition, avoiding the implementation of the morphological track selection algorithm that was previously necessary to reject the tracks due to protons; this possibility would lead to an improvement of the resolution of the concentration measurement. These goals were reached employing PEW (KOH + C2H5OH + H2O) as a chemically etching solution at 70 ºC. This set-up decreased the etching time from 2 hours to 10 minutes. Moreover only tracks from 7Li and α ions are detected, decreasing by consequence the relative error of the calibration from 7% at 1σ of C.L to 5% at 1σ of C.L. . This improved neutron autoradiography method was then applied to 10B concentration measurements in tissues from small animals and cell cultures treated with new carriers, in the frame of the BNCT feasibility study for osteosarcoma [3]. The experiments were conduced testing three categories of carriers: gold nano-particles, liposomes and polymeric nano-particles and BPA as a reference. In particular, 10B loaded liposomes and BPA were administered to Sprague-Dawley rats bearing osteosarcoma. After treatment, healthy bone and muscle and the tumor mass were explanted and prepared for QNCR and AS. The results concerning boron biodistribution obtained in these tissues will be presented and discussed. Boron biodistribution obtained in vivo will be used in the following part of the experiment, consisting in in vivo irradiation of rats with osteosarcoma to test BNCT efficacy in tumor remission and BNCT toxicity for healthy tissues. [1] Silva Bortolussi. Boron Neutron Capture Therapy of Dissiminated Tumors. PhD thesis, Universitá degli studi di pavia Dottorato di ricerca in fisica, 2008. [2] M.A Gadan, S Bortolussi, I Postuma, F Ballarini, P Bruschi, N Protti, D Santoro, S Stella, L Cansolino, A Clerici, C Ferrari, A Zonta, C Zonta, and S Altieri. Set-up and calibration of a method to measure 10b concentration in biological samples by neutron autoradiography. Nuclear Instruments and Methods, pages 51–56, 2012. [3] Silva Bortolussi, Laura Ciani, Ian Postuma, Nicoletta Protti, Piero Bruschi, Cinzia Ferrari, Laura Cansolino, Luigi Panza, Sandra Ristori,Saverio Altieri. Boron concentration measurement by alpha spectrometry and quantitative neutron autoradiography in cell and tissue samples treated with different boronated formulations and administration protocols. Proceedings of 15th International Congress on Neutron Capture Therapy, 2012

Shape fidelity and sterility assessment of 3D printed polycaprolactone and hydroxyapatite scaffolds

Polycaprolactone (PCL) and hydroxyapatite (HA) composite are widely used in tissue engineering (TE). They are fit to being processed with three-dimensional (3D) printing technique to create scaffolds with verifiable porosity. The current challenge is to guarantee the reliability and reproducibility of 3D printed scaffolds and to create sterile scaffolds which can be used for in vitro cell cultures. In this context it is important for successful cell culture, to have a protocol in order to evaluate the sterility of the printed scaffolds. We proposed a systematic approach to sterilise 90%PCL-10%HA pellets using a 3D bioprinter before starting the printing process. We evaluated the printability of PCL-HA composite and the shape fidelity of scaffolds printed with and without sterilised pellets varying infill pattern, and the sterility of 3D printed scaffolds following the method established by the United States Pharmacopoeia. Finally, the thermal analyses supported by the Fourier Transform Infrared Spectroscopy were useful to verify the stability of the sterilisation process in the PCL solid state with and without HA. The results show that the use of the 3D printer, according to the proposed protocol, allows to obtain sterile 3D PCL-HA scaffolds suitable for TE applications such as bone or cartilage repair

Selective uptake of p-boronophenylalanine by osteosarcoma cells for boron neutron capture therapy

Osteosarcoma is the most common non-hematologic primary cancer type that develops in bone. Current osteosarcoma treatments combine multiagent chemotherapy with extensive surgical resection, which in some cases makes necessary the amputation of the entire limb. Nevertheless its infiltrative growth leads to a high incidence of local and distant recurrences that reduce the percentage of cured patients to less than 60%. These poor data required to set up a new therapeutic approach aimed to restrict the surgical removal meanwhile performing a radical treatment. Boron neutron capture therapy (BNCT), a particular radiotherapy based on the nuclear capture and fission reactions by atoms of (10)B, when irradiated with thermal neutrons, could be a valid alternative or integrative option in case of osteosarcoma management, thanks to its peculiarity in selectively destroying neoplastic cells without damaging normal tissues. Aim of the present work is to investigate the feasibility of employing BNCT to treat the limb osteosarcoma. Boronophenylalanine (BPA) is used to carry (10)B inside the neoplastic cells. As a first step the endocellular BPA uptake is tested in vitro on the UMR-106 osteosarcoma cell line. The results show an adequate accumulation capability. For the in vivo experiments, an animal tumor model is developed in Sprague-Dawley rats by means of an intrafemoral injection of UMR-106 cells at the condyle site. The absolute amounts of boron loading and the tumor to normal tissue (10)B ratio are evaluated 2 h after the i.v. administration of BPA. The boron uptake by the neoplastic tissue is almost twice the normal one. However, higher values of boron concentration in tumor are requested before upholding BNCT as a valid therapeutic option in the treatment of osteosarcom

Gamma component dosimetry in the thermal column of the TRIGA reactor in Pavia

This presentation describes the assessment of the gamma rays spectrum and dose. Yhe result have been used to perform dosimetry in cell cultures for in-vitro BNCT studies