Boron nitride nanosheets modified with zinc oxide nanoparticles as novel fillers of dental resin composite

ObjectiveThe purpose of this study was to synthesize boron nitride nanosheets modified with zinc oxide nanoparticles (BNNSs/ZnO) and incorporate them as a novel inorganic filler to get an antibacterial dental resin composite.MethodsThe BNNSs/ZnO nanocomposites were synthesized via the hydrothermal method and characterized by Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscopy (TEM), Energy Dispersive Spectrometer (EDS), X-ray Diffraction (XRD) and Fourier Transform-Infrared (FTIR) Spectroscopy. The BNNSs/ZnO or BNNSs were added into the experimental dental composite with different proportions, respectively. The mechanical and physical properties of the modified dental composite were evaluated. Their antibacterial activities were also assessed by quantitative analysis using Streptococcus mutans (S. mutans).ResultsThe BNNSs/ZnO nanocomposites were successfully synthesized, and the growth of ZnO nanoparticles (ZnO NPs) on boron nitride nanosheets was confirmed. The flexural strength (FS), flexural modulus (FM) and the compressive strength (CS) of all modified resin composites showed no change compared to the control group. The curing depth, degree of conversion, water absorption and solubility of the modified composites were still within the clinical requirement. The antibacterial rates of the modified composites were significantly increased compared to the control group, which can reach 98 % when 0.5 % BNNSs/ZnO was added.SignificanceThe modified dental resin composite with novel BNNSs or BNNSs/ZnO fillers shows significantly high antibacterial activity with suitable physicochemical and mechanical properties.     

The influence of NH3-attaching on the NMR and NQR parameters in the (6,0) zigzag single-walled BPNTs: a density functional study

The structural properties, NMR and NQR parameters in the pristine and NH₃-attached (6,0) zigzag BPNTs model were calculated using DFT methods in order to evaluate the influence of NH₃-attached on the (6,0) zigzag BPNTs for the first time. Geometry optimizations were carried out at the BLYP, B3LYP/6-31G^* levels of theory using the Gaussian 03 program suites. The chemical shielding (CS) parameters for the sites of various ¹¹B and ³¹P atoms and quadrupole coupling constant (C_Q), and asymmetry parameter (η_Q) at the sites of various ¹¹B nuclei were calculated in the pristine and the NH₃-attached (6,0) zigzag BPNTs model. The values of dipole moments detect notable changes due to direct effect of the NH₃-attached on the BPNTs; however, the tip diameters are slightly significant changed in comparison to the pristine models and the gap energies of the NH₃-attached BPNT do not detect any changes in comparison to the pristine model. For the NH₃-attached BPNT, the NMR values for the ¹¹B₁₄ atom which is directly bonded to the NH₃ molecule and the ³¹P atoms that directly bonded to the ¹¹B₁₄ atom in the BPNT are significantly changed. CS^I parameters of the atoms are increased whereas CS^A parameters of the atoms are decreased. The NQR results showed that in BPNTs, the B atoms at the edges of nanotubes play dominant roles in determining the electronic behaviors of BPNTs and the average value of C_Q (¹¹B) and η_Q for the NH₃-attached (6,0) zigzag BPNTs is further in comparison to the pristine model.     

Feasibility evaluation of neutron capture therapy for hepatocellular carcinoma using selective enhancement of boron accumulation in tumour with intra-arterial administration of boron-entrapped water-in-oil-in-water emulsion

Introduction

Hepatocellular carcinoma (HCC) is one of the most difficult to cure with surgery, chemotherapy, or other combinational therapies. In the treatment of HCC, only 30% patients can be operated due to complication of liver cirrhosis or multiple intrahepatic tumours. Tumour cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between ¹⁰B atoms and thermal neutrons, so it is necessary to accumulate a sufficient quantity of ¹⁰B atoms in tumour cells for effective tumour cell destruction by BNCT. Water-in-oil-in-water (WOW) emulsion has been used as the carrier of anti-cancer agents on intra-arterial injections in clinical. In this study, we prepared ¹⁰BSH entrapped WOW emulsion by double emulsifying technique using iodized poppy-seed oil (IPSO), ¹⁰BSH and surfactant, for selective intra-arterial infusion to HCC, and performed simulations of the irradiation in order to calculate the dose delivered to the patients.

Materials and methods

WOW emulsion was administrated with intra-arterial injections via proper hepatic artery on VX-2 rabbit hepatic tumour models. We simulated the irradiation of epithermal neutron and calculated the dose delivered to the tissues with JAEA computational dosimetry system (JCDS) at JRR4 reactor of Japan Atomic Research Institute, using the CT scans of a HCC patient.

Results and discussions

The ¹⁰B concentrations in VX-2 tumour obtained by delivery with WOW emulsion were superior to those by conventional IPSO mix emulsion. According to the rabbit model, the boron concentrations (ppm) in tumour, normal liver tissue, and blood are 61.7, 4.3, and 0.1, respectively. The results of the simulations show that normal liver biologically weighted dose is restricted to 4.9 Gy-Eq (CBE; liver tumour: 2.5, normal liver: 0.94); the maximum, minimum, and mean tumour weighted dose are 43.1, 7.3, and 21.8 Gy-Eq, respectively, in 40 min irradiation. In this study, we show that ¹⁰B entrapped WOW emulsion could be applied to novel intra-arterial boron delivery carrier for BNCT, and we show the possibility to apply BNCT to HCC. We can irradiate tumours as selectively and safety as possible, reducing the effects on neighbouring healthy tissues.     

运用免疫荧光法检测温热对于硼化合物细胞微分布影响

目的硼中子俘获疗法(BNCT)的有效性主要取决于硼-10元素在肿瘤细胞内的聚集。目前的硼检测手段仅限于分析肿瘤组织中硼的平均浓度,不能准确地评价硼化合物(BPA)在组织中的详细分布。先前研究证实温热处理可以提高放疗疗效,本研究通过免疫荧光法检测温热是否对BPA细胞内的微分布有影响。方法通过免疫荧光法分析硼化合物在肿瘤细胞中的分布以及温热对BPA分布的影响。在体外对人肺癌细胞株A549和人头颈部鳞状细胞癌细胞株SAS进行培养,并且加入BPA共培养1h。另外,A549细胞经温热处理1h后,利用抗BPA抗体通过免疫荧光法进行检测。免疫荧光强度通过图像分析软件进行分析。结果检测发现BPA主要聚集于细胞核周围,BPA免疫荧光的强度随着培养基中BPA浓度的增加而增强。尽管在26μg/ml浓度和13μg/ml浓度时,细胞免疫荧光的平均强度相近,但直方图分析发现26μg/ml时细胞主要向高荧光强度区域移动。经温热处理后,BPA在细胞中的分布没有明显增加。结论本研究利用免疫荧光法对BPA在细胞内的分布进行了分析,以上结果暗示温热对肿瘤细胞硼摄取的影响可能主要需要通过改善肿瘤循环、增加肿瘤内BPA的输送来实现。     

等离子喷涂B4C涂层的抗辐射性能研究

目的 研究用等离子技术喷涂的碳化硼(B4C)涂层的抗辐射能力.方法 将0.1 mm厚度B4C涂在16号锰钢上,研究它对加速器产生的6、10、15 MV高能射线,6、9、12、15 MeV高能电子线,60Co γ线和快中子辐射的防护作用.同时将0.1 mm B4C涂在纸板上,研究它对深部X线机的X线辐射的防护作用.结果 等离子喷涂制备B4C涂层对高能X线和60Co γ线没有防护作用.对电子线有一定防护作用,且随深度的增加有增大趋势,但作用不大.对快中子有较大防护作用.对深部X线机X线有防护作用,防护能力较强.0.1 mm厚的涂层就可带来15%的衰减.结论 用等离子技术喷涂的B4C涂层可在医学领域用来防护千伏级射线.     

Biological evaluation of dopamine analogues containing phenylboronic acid group as new boron carriers

As new BNCT reagents, we designed and synthesized dopamine analogues containing phenylboronic acid group, N-3,4-dihydroxyphenethyl-4-dihydroxyborylbenzamide (dopamine–PCBA) and N-[2-(3,4-dihydroxyphenetyl)ethyl]-3-(4-dihydroxyborylphenyl)promionamide (dopamine–CEBA). The efficacies of these compounds have not been investigated for biological samples. Therefore we have carried out experiments with cultured tumor cells and tumor-bearing mice, and evaluated possibility of these compounds as boron carriers. Dopamine–PCBA and dopamine–CEBA were synthesized by coupling between p-carboxyphenylboronic acid (PCBA) or 4-(2-carboxyethyl)benzeneboronic acid (CEBA) and 3,4-(dibenzyloxy)phenethylamine hydrochloride (DBPA-HCl) followed by catalytic hydrogenation using Pd catalyst. The effect of compounds on cell vitality was determined by MTT assay in various cells. In vivo biodistribution of compounds was determined in Balb/c and DDY mice in bearing implanted CT26 cells. These results have demonstrated that dopamine–CEBA was less toxic.     

Development of a prompt gamma neutron activation analysis facility for B concentration measurements at RA-3: Design stage

A PGNAA facility is being developed for ¹⁰B concentration measurements at RA-3 reactor. Its design targets detection limits better than tenths of a microgram and irradiation times on the order of minutes. Computational models were developed, which estimated thermal neutron fluxes in irradiation position to be larger than 10⁹ n cm⁻² s⁻¹. Calculated amounts of photons and fast neutrons make necessary for filter/moderator arrangements. An irradiation device was designed and numerically tested, which is being built and is to be used for performing characterizing measurements.     

硼中子俘获疗法中硼携带剂的研究进展

硼中子俘获疗法（Boron Neutron Capture Therapy,BNCT）是一种新型的二元靶向放疗方法.BNCT是将与肿瘤有特异性亲合力的10B化合物注入人体,10B浓集于肿瘤细胞,经中子束局部照后肿瘤组织中的10B与热中子发生核反应,产生Li-7与α粒子,这些粒子能在细胞水平上杀灭肿瘤细胞,由于周围正常组织中10B的浓度很低,所以对正常组织损伤不大[1].进行BNCT治疗必须满足3个基本条件：一是建立用于BNCT的中子源,能提供BNCT所需的各种中子;二是建立精确的辐射剂量测算体系,以保证BNCT治疗的精确性和安全性;三是合成和肿瘤细胞具有高度亲和力的硼携带剂[2].其中能否研制出对肿瘤具有高度亲和力的硼携带剂对BNCT的疗效和安全性至关重要[3].近年来,用于BNCT治疗的硼携带剂的研究已取得了巨大进展,为肿瘤的BNCT治疗带来了新的希望,现就BNCT硼携带剂的研究现状和展望综述如下.关键词：放疗;肿瘤;硼中子俘获疗法;硼携带剂     

Evaluation of neutron dosimetry on pancreatic cancer phantom model for application of intraoperative boron neutron-capture therapy.

Pancreatic cancer is one of the most difficult neoplasms to cure and there is a need for new combinated therapy. If sufficient boron compound can be targeted accurate to the tumour, Boron Neutron-Capture Therapy (BNCT) can be applied to pancreatic cancer. We administrated BNCT to a cancer with pancreatic cancer patient using intraoperative irradiation. In this study, we performed preliminary dosimetry of a phantom model of the abdominal cavity. The flux of 8>x10(7)n/cm(2)/s (0.1 ratio) was 4.5 cm in depth from the surface in the case of simple irradiation, and the field of thermal neutrons was spread as 13 cm and 11.5 cm were usage of Void and Void with LiF collimation, respectively in thermal (OO-0011) mode. In the case of epithermal (CO-0000) mode, epithermal and fast components are four times higher at the surface level. In the case of mixed beam (OO-0000) mode, thermal neutron flux was the same as thermal neutron mode at a depth of 10 cm, but the gamma-ray component was two times higher than that of thermal neutron mode. With the use of Void and LiF collimation, thermal neutrons were selectively applied to the tumour combined with the CT-imaging of the cancer patient. This means that we could irradiate the tumour selectively and safely as possible, reducing the effects on neighboring healthy tissues. High resolution whole body dosimetry will be necessary to extend the application of BNCT to pancreatic cancer.