Last April, the OSA organized the third installment of the Optical Trapping and Applications (OTA) Topical Meeting as part of the Optics in the Life Sciences Congress in Waikoloa, Hawaii. For three days, authors presented their groundbreaking research in a wide diversity of topics within the optical sciences. The papers published in this issue of Biomedical Optics Express [1] are an assortment of the contributions from authors who presented their work at this past OTA meeting.

In this issue, Al Balushi, Zehtabi-Oskuie, and Gordon make use of an optical trap to detect chemical binding at the single-molecule level [2]. By measuring the optical transmission through a proprietary nanostructure, the authors’ experiments clearly reveal the occurrence of single molecular binding events. The results of the authors forecast a reliable biosensor for single-molecule interactions. Zhang and Marston relate the extinction section to the complex scattering amplitude at the forward direction for a spherical object on which a Bessel beam is incident [3]. Zhang and Marston’s calculations are of relevance to optical trapping experiments in which nondiffracting beams are used. Utilizing an experimental implementation that involves of fluorescence correlation spectroscopy (FCS) and optical trapping, Hu et al present an analysis of the concentration of HIV-like particles in suspension. They demonstrate the average number of particles in an optical trap increases exponentially with the power of the trapping laser [4]. The authors also estimate the range of force-induced concentration enhancement as a means to accurately determine particle concentration values. The final paper, from Yael Roichman's group, explores the applications of combining holographic optical tweezers and confocal imaging [5]. This allows arrays of particles to be positioned in three dimensions and simultaneously imaged in three dimensions using the confocal microscope. The power of this technique is demonstrated via the positioning of a 3d colloidal crystal which is then set in a photocurable gel. Furthermore the technique can be applied straightforwardly to biological systems and a proof of concept example is carried out looking at nuclear division in yeast cells. The work holds great promise for more advanced parallel studies examining processes such as cellular drug uptake and cell division.