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Photocatalytic water splitting using solar energy for hydrogen production offers a promising alternative form of storable and clean energy for the future. To design an artificial photosynthesis system that is cost-effective and scalable, earth abundant elements must be used to develop each of the components of the assembly. To develop artificial photosynthetic systems, we need to couple a catalyst for proton reduction to a photosensitizer and understand the mechanism of photo-induced electron transfer from the photosensitizer to the catalyst that serves as the fundamental step for photocatalysis. Therefore, our work is focused on the study of light driven electron transfer kinetics from the quantum dot systems made with inorganic chalcogenides in the presence of Ni-based reduction catalysts. Herein, we report the synthesis and characterization of four Ni(II) complexes of tetradentate ligands with amine and pyridine functionalities (N2/Py2) and their interactions with CdTe quantum dots stabilized by 3-mercaptopropionic acid. The lifetime of the quantum dots was investigated in the presence of the Ni complexes and absorbance, emission and electrochemical measurements were performed to gain a deeper understanding of the photo-induced electron transfer process.

We studied the influence of magnetite nanoparticles (FeO•Fe 2 O 3 ) and quantum dots (CdSe/ZnS coated with mercaptopropionic acid) on the expression of 5 common reference genes (BA, B2M, PPIA, UBC, and YWHAZ) in peripheral blood cells from 20 volunteers by reverse transcription PCR method. The stability of the expression of reference genes varied depending of the cells type and chemical structure of nanoparticles. The level of YWHAZ mRNA after exposure by nanoparticles demonstrated highest stability in lymphocytes, neutrophils, and monocytes. Stability of YWHAZ expression was confirmed by Western blotting. Our findings suggest that YWHAZ is the most suitable as the reference gene.

An ultrasensitive label-free impedimetric immunosensor is constructed by modifying a 3-mercaptoproponic acid (MPA) monolayer on highly rough gold nanostructure (AuNS)-electrodeposited screen printed carbon electrodes (SPCEs) for the detection of small molecular weight drugs (SMWDs), such as salbutamol (SAL). The SPCEs preoxidized in a 0.1 M H 2 SO 4 solution (called po-SPCE H2SO4 ) are electrodeposited with the AuNS to increase the roughness factor to 23.64 ± 1.76, larger than the AuNS/po-SPCE NaOH or the AuNS/po-SPCE PBS . Furthermore, the MPA modified layer as a link for the anti-SAL immobilization to give the immunosensors an impedimetric signal-to-noise ratio larger than the 11-mercapto-undecanoic acid- and 16-mercaptohexadecanoic acid-modified layer, due to the lower interfacial impedance of the MPA monolayer. The MPA/AuNS/po-SPCE H2SO4 -based immunosensors have a wide linear range of 1 fg mL -1 to 1 ng mL -1 and a limit of detection of 0.6 fg mL -1 . Moreover, the immunosensors can practically quantify the SAL concentrations in 1000 times-diluted serum samples with good recovery.

The exciton generation and recombination dynamics in semiconductor nanocrystals are very sensitive to small variations in dimensions, shape and surface capping. In the present work CdTe quantum dots are synthesized in water using 3-mercaptopropionic acid and 1-thioglycerol as stabilizers. Nanocrystals with an average dimension of 4.0 ± 1.0 and 3.7 ± 0.9 nm were obtained, when 3-mercaptopropionic acid or 1-thioglycerol, respectively, was used as a capping agent. The steady-state characterization shows that the two types of colloids have different luminescence behavior. In order to investigate the electronic structure and the dynamics of the exciton state, a combined study in the time domain has been carried out by using fluorescence time-correlated single photon counting and femtosecond transient absorption techniques. The electron-hole radiative recombination follows the non-exponential decay law for both colloids, which results in different average decay time values (of the order of tens of nanoseconds) for the two samples. The data demonstrate that the process is slower for 1-thioglycerol-stabilized colloids. The ultrafast transient absorption measurements are performed at two different excitation wavelengths (at the band gap and at higher energies). The spectra are dominated in both types of samples by the negative band-gap bleaching signals although transient positive absorption bands due to the electrons in the conduction band are observable. The analysis of the signals is affected by the different interactions with the defect states, due to ligand capping capacities. In particular, the data indicate that in 1-thioglycerol-stabilized colloids the non-radiative recombination processes are kinetically more competitive than the radiative recombination. Therefore the comparison of the data obtained from the two samples is interpreted in terms of the effects of the capping agents on the electronic relaxation of the colloids.

The conformation change of bovine hemoglobin (Hb) during the unfolding process induced by urea and acid was investigated by an electrochemical method. Hb unfolding induced by urea of different concentrations was realized by bonding Hb onto a 3-mercaptopropionic acid (MPA) modified gold electrode. The difference in unfolding percentage showed that the Hb unfolding induced by urea was a two-step, three-state transition process, while the unfolding induced by acid was a two-state transition process. The results obtained by the electrochemical method coincided closely with those obtained by UV-vis spectroscopy and fluorescence spectroscopy. Some thermodynamic parameters during the conformational change were also calculated to study the intermediate state during the Hb unfolding process. The present work may lead to an easy and effective way to study metalloproteins unfolding, and holds great promise for the design of novel sensitive biosensors.

A quartz-crystal microbalance immunosensor (QCM) has been developed for the direct determination of Schistosoma-japonicum-infected rabbit serum. A self-assembled monolayer with carboxyl groups was first coated on a gold electrode of a quartz-crystal resonator by the spontaneous adsorption of 3-mercaptopropionic acid. Schistosoma-japonicum molecular antigen of 32 kD molecular weight was then covalently attached to the crystal surface. The QCM immunosensor was used to detect infected rabbit serum (IRS49-2000); a maximum titer of 1:800 was achieved.