Chemically bound gold nanoparticle arrays on silicon: assembly, properties and SERS study of protein interactions

A highly reproducible and facile method for formation of ordered 2 dimensional arrays of CTAB protected 50 nm gold nanoparticles bonded to silicon wafers is described. The silicon wafers have been chemically modified with long-chain silanes terminated with thiol that penetrate the CTAB bilayer and chemically bind to the underlying gold nanoparticle. The silicon wafer provides a reproducibly smooth, chemically functionalizable and non-fluorescent substrate with a silicon phonon mode which may provide a convenient internal frequency and intensity calibration for vibrational spectroscopy. The CTAB bilayer provides a potentially biomimetic environment for analyte, yet allows a sufficiently small nanoparticle separation to achieve a significant electric field enhancement. The arrays have been characterized using SEM and Raman spectroscopy. These studies reveal that the reproducibility of the arrays is excellent both between batches (< 10% RSD) and across a single batch (< 5% RSD). The arrays also exhibit good stability, and the effect of temperature on the arrays was also investigated. The interaction of protein and amino acid with the nanoparticle arrays was investigated using Raman microscopy to investigate their potential in bio-SERS spectroscopy. Raman of phenylalanine and the protein bovine pancreatic trypsin inhibitor, BPTI were studied using 785 nm excitation, coincident with the surface plasmon absorbance of the array. The arrays exhibit SERS enhancements of the order of 2.6 x 104 for phenylalanine, the standard deviation on the relative intensity of the 1555 cm-1 mode of phenylalanine is less than 10% for 100 randomly distributed locations across a single substrate and less than 20% between different substrates. Significantly, comparisons of the Raman spectra of the protein and phenlyalanine in solution and immobilized on the nanoparticle arrays indicates that the protein is non-randomly orientated on the arrays. Selective SERS enhancements suggest that aromatic residues penetrate through the bilayer inducing conformational changes in the protein

Biocompatible Nanocomplexes for Molecular Targeted MRI Contrast Agent

Accurate diagnosis in early stage is vital for the treatment of Hepatocellular carcinoma. The aim of this study was to investigate the potential of poly lactic acid–polyethylene glycol/gadolinium–diethylenetriamine-pentaacetic acid (PLA–PEG/Gd–DTPA) nanocomplexes using as biocompatible molecular magnetic resonance imaging (MRI) contrast agent. The PLA–PEG/Gd–DTPA nanocomplexes were obtained using self-assembly nanotechnology by incubation of PLA–PEG nanoparticles and the commercial contrast agent, Gd–DTPA. The physicochemical properties of nanocomplexes were measured by atomic force microscopy and photon correlation spectroscopy. The T1-weighted MR images of the nanocomplexes were obtained in a 3.0 T clinical MR imager. The stability study was carried out in human plasma and the distribution in vivo was investigated in rats. The mean size of the PLA–PEG/Gd–DTPA nanocomplexes was 187.9 ± 2.30 nm, and the polydispersity index was 0.108, and the zeta potential was −12.36 ± 3.58 mV. The results of MRI test confirmed that the PLA–PEG/Gd–DTPA nanocomplexes possessed the ability of MRI, and the direct correlation between the MRI imaging intensities and the nano-complex concentrations was observed (r = 0.987). The signal intensity was still stable within 2 h after incubation of the nanocomplexes in human plasma. The nanocomplexes gave much better image contrast effects and longer stagnation time than that of commercial contrast agent in rat liver. A dose of 0.04 mmol of gadolinium per kilogram of body weight was sufficient to increase the MRI imaging intensities in rat livers by five-fold compared with the commercial Gd–DTPA. PLA–PEG/Gd–DTPA nanocomplexes could be prepared easily with small particle sizes. The nanocomplexes had high plasma stability, better image contrast effect, and liver targeting property. These results indicated that the PLA–PEG/Gd–DTPA nanocomplexes might be potential as molecular targeted imaging contrast agent

Analysis of Performance Characteristics of Intermediate-Temperature Disk Type SOFC Using Pure Hydrogen

In this study, a one-dimensional simulation code of intermediate-temperature disk type SOFC is developed. The single cell voltage−current density characteristic curves and the temperature dependence of the single cell voltage are calculated. The numerically estimated single cell voltage is about 0.02 V higher than that of the experimental result when the electronic conductivity of the electrolyte is not taken into consideration. To address this discrepancy, the electronic resistivity of 1500 Ωcm is incorporated in the simulation code. The numerically obtained single cell voltage coincides well with the experimental one in this case. The dependence of the single cell voltage on the cell temperature is also investigated. It is made clear that the single cell voltage takes the highest value when the cell temperature is about 760°C for nominal current density of 0.3 A/cm2

Carcinomatous Pericarditis in 3 Breast Cancer Patients with Long-Term Survival

With advances in drug treatment of breast cancer, the number of patients experiencing cardiac toxicity or carcinomatous pericarditis is expected to increase. These conditions can cause cardiac tamponade, which is a potentially fatal condition requiring prompt diagnosis and treatment. We experienced 3 breast cancer patients with cardiac tamponade due to carcinomatous pericarditis who survived for prolonged periods after treatment with pericardiocentesis and intrapericardial instillation. The 3 women were 68, 46 and 46 years old, respectively, and receiving treatment for recurrent breast cancer after surgery. They developed dyspnea and cough and were diagnosed with cardiac tamponade by echocardiography. Pericardiocentesis was performed, and cytology of the effusion confirmed the diagnosis of carcinomatous pericarditis. Intrapericardial instillation of cisplatin reduced the cardiac effusion, ameliorating symptoms. The patients died 13, 31 and 14 months later, respectively. In our clinical review of 13 other cases of cardiac tamponade due to breast cancer, 85% achieved local control after the aforementioned local treatments, which were considered to be effective. Although the overall prognosis was poor with a median survival time of only 4 months, some patients were able to survive more than 1 year after local treatment with subsequent systemic therapy