Recently, there has been significant interest in the synthesis and potential applications of semiconductor nanotubes (NTs). In this context, many efforts have been invested in developing new routes to control and engineer their surface chemistry. We report herein on a simple route to differentially and selectively functionalize the inner and outer surfaces of silicon nanotubes (SiNTs) with organic molecular layers containing different functional groups and hydrophobicity/hydrophilicity chemical nature, via covalent binding, to give nanotubular structures with dual chemical properties. Significantly, our unique synthetic approach can be further extended to directly form hollow crystalline nanotubular structures with their inner/outer surfaces independently and selectively altered chemically. Additionally, SiNTs inner and/or outer walls can be selectively decorated with metal nanoparticles. Both inner and outer walls can be individually and separately modified with the same metal nanoparticles, with differe...

Wall-selective chemical alteration of silicon nanotube molecular carriers.

Immobilization of antibodies through the surface regions having the highest density in lysine groups on finally inert support surfaces

Chemical modification with plasma ion irradiation (plasma activation) is demonstrated on a bio-nanosensor based on poly(ethylene glycol)-grafted single-walled carbon nanotubes (PEG-SWNTs). By X-ray photoelectron spectroscopy (XPS) analysis, peaks that correspond to CO and COOH radicals are observed. In addition, the evaluation of the characteristic responses of the bio-nanosensor using a bovine serum albumin (BSA) antigen or oligonucleotide reveals an increase in impedance due to an antigen–antibody reaction or oligonucleotide hybridization. From these results, the bio-nanosensor is found to react with a short response time (60 s).

https://iopscience.iop.org/article/10.1143/JJAP.47.2068/pdf

Chemical modification of carbon nanotube based bio-nanosensor by plasma activation

In this study, we have applied atomic layer deposition (ALD) for the fabrication of CNT-FET biosensors.Biosensor operation was confirmed by CNT-FETs fabricated using the ALD passivation film. CNTs were grown on a SiO2(100 nm)/p+-Si substrate by alcohol catalytic chemical vapor deposition. Following the fabrication of the CNT-FETs, HfO2 film (50 nm) with a large dielectric constant was deposited on the device surface by ALD at 250degC. HfO2 was chosen as a passivation/top-gate insulator to realize a large transconductance of the device. SEM image of the HfO2-deposited sample, indicates that the step coverage is very good in the case of the ALD. The devices with the top gate were used for biosensors. The self-assembled-monolayer (SAM) film with carboxyl group was formed on the top-gate FET surface by immersing the device in 3-Mercaptopropionic acid. Biosensor measurement was performed by measuring the ID when the enzyme Cytochrome c (pl= 10.25, 2.7mg/ml) containing solution was dropped into the phosphate-buffer (PB) solution (pH=7.0) where the SAM-coated device was immersed. Thus we have successfully fabricated CNT-FET biosensors using ALD HfO2 as a passivation film with little degradation of the ID.

Fabrication Process of Carbon Nanotube FETs Using ALD Passivation for Biosensors

Atomistic Simulation of Gas Adsorption in Carbon Nanostructures

Antigen sensors using carbon nanotube field effect transistors (CNT-FETs) were fabricated. In order to avoid the problem of exposing source and drain electrodes directly to the phosphate buffered saline (PBS) solution, source and drain electrodes were covered with evaporated SiO film. The immobilization of antibodies on the device surface was confirmed by the observation of fluorescence. Drain current in the sensor device was decreased by the antibody–antigen binding, which suggests a potential use of CNT-FETs as antigen sensors.

Fabrication of Antigen Sensors Using Carbon Nanotube Field Effect Transistors

Association reactions by femtosecond laser filamentation in gaseous C2H4 were studied by time-of-flight mass spectrometry of neutral reaction products. Direct sampling from the reaction cell to a mass spectrometer via a differential pumping stage allowed the identification of various hydrocarbon molecules C n H m with n = 3-7 and m = 4-7, which includes species not observed in the previous studies. It was found that products containing three and four carbon atoms dominate the mass spectrum with smaller yields for higher-mass species, suggesting that carbon chain growth proceeds through the reaction with C2H4 in the reaction cell. The product distribution showed a clear dependence on the laser pulse energy for filamentation.

Association Reaction of Gaseous C2H4 in Femtosecond Laser Filaments Studied by Time-of-Flight Mass Spectrometry.

The secure implementation of the Greatest Common Divisor (GCD) algorithm is fundamental for many cryptographic schemes. The binary GCD algorithm has a highly input-dependent behavior. Therefore, we must carefully implement the binary GCD used in cryptographic systems. However, it has been noted that the binary GCD algorithm implemented in OpenSSL 1.1.0-1.1.0h and 1.0.2b-1.0.2o is not secure. Aldaya et al. presented this vulnerability at CHES2019. They also proposed a side-channel attack to collect sequences of operations performed by the binary GCD algorithm and an error correction algorithm (AGTB algorithm) to recover the LSBs of secret keys from the noisy sequences. In this paper, we propose an error correction algorithm that, like the AGTB algorithm, focuses on only a single type of error. We evaluate our algorithm using numerical experiments that reveal that our algorithm achieves a higher recovery rate than the AGTB algorithm. 

Kentaro Tani

Papers

Fabrication of Antigen Sensors Using Carbon Nanotube Field Effect Transistors

Association Reaction of Gaseous C2H4 in Femtosecond Laser Filaments Studied by Time-of-Flight Mass Spectrometry.

HS-Based Error Correction Algorithm for Noisy Binary GCD Side-Channel Sequences