'Click' bioconjugation of a well-defined synthetic polymer and a protein transduction domain

The copper-catalyzed 1,3-dipolar 'click' cycloaddition of azides and alkynes was studied to link a model synthetic polymer to a sequence-defined protein transduction domain (PTD). The bromine chain-ends of a well-defined polystyrene ( PS) sample synthesized by atom transfer radical polymerization (M-n 2200 g mol(-1), M-w/M-n 1.21) were first transformed into azide functions by substitution with sodium azide, and subsequently reacted with an alkyne-functionalized PTD (i.e., the oligopeptide sequence GGYGRKKRRQRRRG, also known as the TAT peptide). The click bioconjugation proceeded successfully at room temperature, thus affording the targeted PS-b-GGYGRKKRRQRRRG bioconjugate in high yields. However, a slight molar excess of polystyrene was required for optimal coupling

Study of the neutron quantum states in the Earth's gravitational field

We studied the neutron quantum states in the potential well formed by the Earth's gravitational field and a horizontal mirror. The estimated characteristic sizes of the neutron wave functions in two lowest quantum states correspond to their expectations with an accuracy of ~25%. A spatial density distribution in a standing neutron wave above a mirror was measured for a set of a few lowest quantum states. A position-sensitive neutron detector with an extra high spatial resolution of 1-2 mu m was developed and tested for this particular task. Although this experiment was not designed or optimized to search for an additional short-range force, nevertheless it allowed us to slightly improve the published boundary in the nanometer range of characteristic distances. We studied systematical uncertainties in the chosen "flow-through" method as well as the feasibility to improve further the accuracy in this experimen

Investigation of the neutron quantum states in the Earth's gravitational field

We studied the neutron quantum states in the potential well formed by the Earth's gravitational field and a horizontal mirror. The estimated characteristic sizes of the neutron wave functions in two lowest quantum states correspond to their expectations with an accuracy of approximate to 25 %. The spatial density distribution in a standing neutron wave above a mirror was measured for a set of a few lowest quantum states. A position-sensitive neutron detector with an extra high spatial resolution of 1 mu m to 2 mu m was developed and tested for this particular task. Although this experiment was not designed or optimized to search for an additional short-range force, nevertheless it allowed us to slightly improve the published boundary in the nanometer range of characteristic distances. We studied systematical uncertainties in the chosen "flow-through" method as well as the feasibility to improve further the accuracy in this experiment