Combined small and large magnetic nanoparticle extraction and concentration from biofluids for non-toxic detection of biomarkers.

We propose a novel non-toxic method of diagnostic biomarker extraction and concentration from biofluids. The method is based on the usage of (1) magnetic nanoparticles of a few nanometres in size bearing molecular traps for biomarkers on their surface and (2) additional larger (several tens of nanometres) magnetic nanoparticles for catching smaller magnetic nanoparticles in a strong magnetic field gradient with their consequent concentration into the detection area. It is shown that the interference of an external permanent gradient magnetic field with the magnetic field of large magnetic nanoparticles allows one to catch small magnetic nanoparticles from their trajectories in a fluid at a distance around ten radii of the large nanoparticles.

Optical plasmon nanostrip probe as an effective ultrashort pulse delivery system.

In this paper, we analyze the ultrafast temporal and spectral responses of optical fields in tapered and metalized optical fibers (MOFs) and optical plasmon nanostrip probes (NPs). Computational experiment shows that output pulses of the NPs are virtually unchanged in shape and duration for input pulses with a duration of >1 fs and are not sensitive to changes in the parameters of the probe (such as convergence angle and taper length), while local enhancement of the electric field intensity reaches 300 times at the NP apex. Compared with the NPs, MOFs lead to significant output pulse distortions, even for input pulses with a duration of 10 fs.