The properties and applications of single-molecule DNA sequencing

Single-molecule sequencing enables DNA or RNA to be sequenced directly from biological samples, making it well-suited for diagnostic and clinical applications. Here we review the properties and applications of this rapidly evolving and promising technology

Symmetric spatio-temporal focusing of ultrashort pulses

Simultaneous spatio-temporal focusing of few-cycle pulses is usually performed by stretcher-compressor configurations causing pulse-front tilt. By shaping and superimposing two reciprocal sub-beams, opposite tilts can compensate each other. Pulse propagation for asymmetric and symmetric focusing of near infrared 5-fs-pulses is studied by numerical simulations and proof-of-principle experiments.</jats:p

Symmetric spatio-temporal focusing of ultrashort pulses

Simultaneous spatio-temporal focusing of few-cycle pulses is usually performed by stretcher-compressor configurations causing pulse-front tilt. By shaping and superimposing two reciprocal sub-beams, opposite tilts can compensate each other. Pulse propagation for asymmetric and symmetric focusing of near infrared 5-fs-pulses is studied by numerical simulations and proof-of-principle experiments

Symmetric spatio-temporal focusing of ultrashort pulses

Simultaneous spatio-temporal focusing of few-cycle pulses is usually performed by stretcher-compressor configurations causing pulse-front tilt. By shaping and superimposing two reciprocal sub-beams, opposite tilts can compensate each other. Pulse propagation for asymmetric and symmetric focusing of near infrared 5-fs-pulses is studied by numerical simulations and proof-of-principle experiments

Distinction of nucleobases - A tip-enhanced Raman approach

The development of novel DNA sequencing methods is one of the ongoing challenges in various fields of research seeking to address the demand for sequence information. However, many of these techniques rely on some kind of labeling or amplification steps. Here we investigate the intrinsic properties of tip-enhanced Raman scattering (TERS) towards the development of a novel, label-free, direct sequencing method. It is known that TERS allows the acquisition of spectral information with high lateral resolution and single-molecule sensitivity. In the presented experiments, single stranded adenine and uracil homopolymers were immobilized on different kinds of substrates (mica and gold nanoplates) and TERS experiments were conducted, which demonstrated the reproducibility of the technique. To elucidate the signal contributions from the specific nucleobases, TERS spectra were collected on single stranded calf thymus DNA with arbitrary sequence. The results show that, while the Raman signals with respect to the four nucleobases differ remarkably, specific markers can be determined for each respective base. The combination of sensitivity and reproducibility shows that the crucial demands for a sequencing procedure are met