The appearance of drug-resistant (especially, multidrug-resistant (MDR)) tumor cells is a major obstacle to the success of chemotherapy; thus, the development of effective anti-MDR agents plays an important role in the tumor therapy. In this report, the considerable effect of nano-TiO2 and UV illumination on the drug resistance of target cancer cells has been explored, and the fresh evidence from the fluorescence spectroscopy and microscopy as well as electrochemical studies demonstrates the significant enhancement effect of nano-TiO2 to the drug uptake by drug-resistant leukemia cells. Besides, it is also observed that the combination of the nano-TiO2 and UV irradiation with the accompanying anticancer drug daunorubicin could provoke some considerable changes of the cell membrane of the target leukemia cells, which indicates that nano-TiO2 could not only increase the drug accumulation in target cancer cells, but also act as an effective anti-MDR agent to inhibit the relative drug resistance.

The electrochemical redox-induced contact angle changes of hemoglobin droplets in the absence and presence of tetraheptylammonium-capped Fe3O4 nanoparticles have been explored by using in situ electrochemical contact angle measurements. The results indicate that the electrochemical redox process may lead to some structure changes of hemoglobin (Hb), which could further induce the hydrophobic-to-hydrophilic changes of the relative droplets. Our observations demonstrate that hemoglobin could self-assemble on the surface of the functionalized Fe3O4 nanoparticles as Hb–Fe3O4 nanocomposites, which may contribute to much more significant change of the electrochemical redox-induced contact angle values than that with free nano-Fe3O4. These results suggest that in situ electrochemical contact angle measurements could be readily applied as a new and convenient method to detect some specific biological process.

We report a novel approach to enhance the efficient accumulation and utilization of anticancer drug daunorubicin on cancer cells through the combination with CdS nanoparticles. Our observations using confocal fluorescence scanning microscopy as well as electrochemical analysis methods demonstrate that CdS nanoparticles can readily bind with daunorubicin on the external membrane of the targeted cells and facilitate the uptake of drug molecules in the human leukemia K562 cells. Besides, our results also indicate that the competitive binding of CdS nanoparticles with accompanying anticancer drug to the membrane of leukemia K562 cells could efficiently prevent the drug release by the drug-sensitive and drug-resistant leukemia cells and thus inhibit the possible multidrug resistance of cancer cells, which could be further utilized to improve the future drug efficiency in respective tumor chemotherapies.

Asymmetrical deformation of an aqueous electrolyte droplet bridging two bipyridinium-modified Au-electrodes is achieved upon the application of voltages resulting in the selective reduction and oxidation of the bipyridinium units on the two electrodes. The different contact angles at the right and left sides of the droplet originate from the electrochemically controlled changes of the wetting properties of the modified electrodes. The reversible and repeatable formation of an electrolytic contact between a side Ptwire electrode and the respective bottom Au-electrode is controlled by the voltage applied between the two bottom Au-electrodes.

Three kinds of magnetic nanoparticle, tetraheptylammonium capped nanoparticles of Fe3O4, Fe2O3 and Ni have been synthesized, and the synergistic effect of these nanoparticles on the drug accumulation of the anticancer drug daunorubicin in leukaemia cells has been explored. Our observations indicate that the enhancement effect of Fe3O4 nanoparticles is much stronger than that of Fe2O3 and Ni nanoparticles, suggesting that nanoparticle surface chemistry and size as well as the unique properties of the magnetic nanoparticles themselves may contribute to the synergistic enhanced effect of the drug uptake of targeted cancer cells.

The biomolecular binding behavior of anticancer drug dacarbazine (DTIC) in the presence of titanium dioxide (TiO2) nanoparticle interface has been studied by using electrochemical methods. The results indicate that the presence of TiO2 nanoparticles can obviously increase the binding affinity of DTIC to DNA or DNA bases and significantly enhance the detection sensitivity for the relative biomolecular recognition.

A non-dense long-chain tethered bipyridinium monolayer linked to an electrode support is reversibly retracted and attracted from and to the electrode respectively by the applied potential. The "molecular machinery" functions of the monolayer are probed by chronoamperometry and contact angle measurements.

The interaction between fl-cyclodextrin (β-CD) and riboflavin together with its electrogenerated intermediate anion radicals has been specifically investigated by in situ electrochemical UV-visible spectroscopy. It appears that the anion radicals are included more tightly than the parents and stabilized in the special microenvironment of the β-CD cavity. The utility of β-CD for probing the existence of an unstable intermediate species at the electrode is also demonstrated.

The effect of fl-cyclodextrin (fl-CD) on the spectral properties of quinine molecules has been specifically studied by absorption/fluorescence and Fourier transform infrared (FTIR) spectroscopy. In particular, FTIR studies of the complexation of aqueous quinine hydrochloride with fl-CD provide fresh insight into the molecular structure of the complex and reveal some important information in relation to the molecular interactions of the cyclodextrin complex system. Nuclear magnetic resonance data support the inclusion conformation of the interaction sites and the presence of hydrogen bonds which stabilize the complexes.

In situ electrochemical static contact angle measurements are employed to probe photoinduced electron transfer processes at electrode surfaces. Photosystems consisting of tris(2,20-bipyridyl)ruthenium(II), (Ru(bpy)32+), N,N0-dimethyl-4,40-bipyridinium (MV2+), Na2EDTA or CdS nanoparticles, MV2+, triethanolamine (TEOA) were included in aqueous droplets that were coupled with a ferrocene monolayer-functionalized electrode. Upon the oxidation of the interface (0.5 V vs. Ag quasi-reference electrode), and the illumination of the systems, photoinduced electron transfer to the modified electrode proceeds. The electron transfer processes yield photocurrents, and the photoelectrochemical transformations are followed by contact angle measurements. Similarly, a CdS/bipyridinium monolayer is assembled on an Au electrode support. The redox transformations of the bipyridinium units control the hydrophilic/hydrophobic properties of the interface, and are followed by contact angle analyses. Irradiation of the CdS/bipyridinium layer associated with the electrode biased at -0.3 V yields a photocurrent. The changes in the wetting properties of the irradiated interface are investigated by contact angle measurements.