11/2018. “
Picoanalysis: Picoanalysis of Drugs in Biofluids with Quantitative Label‐Free Surface‐Enhanced Raman Spectroscopy.” Small, 14, 47.
AbstractThe enormous increase of Raman signal in the vicinity of metal nanoparticles allows surface‐enhanced Raman spectroscopy (SERS) to be employed for label‐free detection of substances at extremely low concentrations. However, the ultimate potential of label‐free SERS to identify pharmaceutical compounds at low concentrations, especially in relation to biofluid sensing, is far from being fully realized. Opioids are a particular challenge for rapid clinical identification because their molecular structural similarities prevent their differentiation with immunolabeling approaches. In this paper, a new method called quantitative label‐free SERS (QLF‐SERS) which involves the formation of halide‐conjugated gold nanoclusters trapping the analyte of interest near the SERS hot spots is reported, and it is demonstrated that it yields a 105 fold improvement in the detection limit over previously reported results for the entire class of clinically relevant opioids and their metabolites. Measurements of opioid concentrations in multicomponent mixtures are also demonstrated. QLF‐SERS has comparable detection limits as currently existing laboratory urine drug testing techniques but is significantly faster and inexpensive and, therefore, can be easily adapted as part of a rapid clinical laboratory routine.
6/2018. “
Wavefront Reconstruction in Holographic Scanning Microscopy.” In Optical Society of America.
Publisher's VersionAbstractA reconstruction algorithm for holographic scanning microscopy should take into account scanning-associated phase shifts. Here we present the stable, not prone to noise, algorithm which does not require additional recording of the object wave intensity.
2018. “
Multispectral light scattering endoscopic imaging of esophageal precancer.” Light: Science & Applications, 7, 4.
Publisher's VersionAbstractEsophageal adenocarcinoma is the most rapidly growing cancer in America. Although the prognosis after diagnosis is unfavorable, the chance of a successful outcome increases tremendously if detected early while the lesion is still dysplastic. Unfortunately, the present standard-of-care, endoscopic surveillance, has major limitations, since dysplasia is invisible, often focal, and systematic biopsies typically sample less than one percent of the esophageal lining and therefore easily miss malignancies. To solve this problem we developed a multispectral light scattering endoscopic imaging system. It surveys the entire esophageal lining and accurately detects subcellular dysplastic changes. The system combines light scattering spectroscopy, which detects and identifies invisible dysplastic sites by analyzing light scattered from epithelial cells, with rapid scanning of the entire esophageal lining using a collimated broadband light beam delivered by an endoscopically compatible fiber optic probe. Here we report the results of the first comprehensive multispectral imaging study, conducted as part of routine endoscopic procedures performed on patients with suspected dysplasia. In a double-blind study that characterized the system’s ability to serve as a screening tool, 55 out of 57 patients were diagnosed correctly. In addition, a smaller double-blind comparison of the multispectral data in 24 patients with subsequent pathology at locations where 411 biopsies were collected yielded an accuracy of 90% in detecting individual locations of dysplasia, demonstrating the capability of this method to serve as a guide for biopsy.