By positioning a single gold particle at different locations along the length axis on a cantilever based mass sensor, we have investigated the effect of mass position on the mass responsivity and compared the results to simulations. A significant improvement in quality factor and responsivity was achieved by operating the cantilever in the fourth bending mode thereby increasing the intrinsic sensitivity. It is shown that the use of higher bending modes grants a spatial resolution and thereby enhances the functionality of the cantilever based mass sensor.

This article describes the preparation of a graphene electrode modified with a new conjugate of peptide nanotubes and folic acid for the selective detection of human cervical cancer cells over-expressing folate receptors. The functionalization of peptide nanotubes with folic acid was confirmed by fluorescence microscopy and atomic force microscopy. The peptide nanotube–folic acid modified graphene electrode was characterized by scanning electron microscopy and cyclic voltammetry. The modification of the graphene electrode with peptide nanotube–folic acid led to an increase in the current signal. The human cervical cancer cells were bound to the modified electrode through the folic acid–folate receptor interaction. Cyclic voltammograms in the presence of [Fe(CN)₆]^3−/4− as a redox species demonstrated that the binding of the folate receptor from human cervical cancer cells to the peptide nanotube–folic acid modified electrode lowered the electron transfer resulting in a decrease in the measured current. A detection limit of 250 human cervical cancer cells per mL was obtained. Control experiments confirmed that the peptide nanotube–folic acid electrode specifically recognized folate receptors. The modified electrode described here opens up new possibilities for future applications in early stage diagnoses of diseases where cells over-express folate receptors, such as in cancer or leishmaniasis disease.

Different techniques available to manipulate biological samples in a controlled manner are reviewed. The advantages and drawbacks are discussed together with ex

Nanomechanical resonators have been monolithically integrated on preprocessed complementary metal-oxide-semiconductor (CMOS) chips. Fabricated resonator systems have been designed to have resonance frequencies up to 1.5 MHz. The systems have been characterized in ambient air and vacuum conditions and display ultrasensitive mass detection in air. A mass sensitivity of $4\mathrm{ag}∕\mathrm{Hz}$ has been determined in air by placing a single glycerine drop, having a measured weight of 57 fg, at the apex of a cantilever and subsequently measuring a frequency shift of 14.8 kHz. CMOS integration enables electrostatic excitation, capacitive detection, and amplification of the resonance signal directly on the chip.

Spectra of laser-produced plasmas of the elements from tin to iodine contain weak bands of quasicontinuum overlaid by weak emission lines in the 70–120-Å region. Multiconfiguration-Dirac-Fock calculations show that these features are consistent with theoretical spectra for 4${\mathit{d}}^{\mathit{N}\mathrm{-}}$4${\mathit{d}}^{\mathit{N}\mathrm{-}1}$(5f+6p) transitions in a number of adjacent ion stages which are predicted to produce unresolved transition arrays (UTA) in this spectral region. Moreover, the calculations predict a gradual decrease of 4d-5f oscillator strength with increasing ionization up to the eleventh spectrum where Jgf(4d-5f)≊0. However, inclusion of configuration interaction effects between the 4${\mathit{d}}^9$nf levels showed that 4${\mathit{d}}^9$4f and 4${\mathit{d}}^9$5f mixing shifts this minimum to the thirteenth spectrum. The theoretical data were then parametrized within the UTA formalism and the different order moments corresponding to weighted mean energy, variance, and skewness coefficient evaluated.