The quantitative measurement of structural alterations at the nanoscale level is important for understanding the physical state of biological samples. Studies have shown that the progression of cancer is associated with the rearrangements of building blocks of cells/tissues such as DNA, RNA, lipids, etc. Partial wave spectroscopy is a recently developed mesoscopic physics-based spectroscopic imaging technique which can detect such nanoscale changes in cells/tissues. At present, chemotherapy drug treatment is the only effective form of treatment; however, the development of drug-resistant cancer cells is a major challenge for this treatment. Earlier PWS analyses of prostate cancer cells, a 2D structure, have shown that drug-resistant cancer cells have a higher degree of structural disorder compared to drug-sensitive cancer cells. At the same time, structural properties of the metastasize tumor grown to 3D structure from drug-resistant and drugsensitive cancer cells within the body is not well studied. In this paper, the structural properties of tissues from grown 3D tumors, generated from docetaxel drug-sensitive and drug-resistant prostate cancer cells xenografted into a mouse model, are studied. The results show that xenografted tumor tissues from drug-resistant cells have higher disorder strength than the tumor generated from drugsensitive prostate cancer cells. Potential applications of the technique to assess chemotherapy effectiveness in cancer treatment are discussed.

. Significance: Light is a good probe for studying the nanoscale-level structural or molecular-specific structural properties of brain cells/tissue due to stress, alcohol, or any other abnormalities. Chronic alcoholism during pregnancy, i.e., fetal alcoholism, being teratogenic, results in fetal alcohol syndrome, and other neurological disorders. Understanding the nano-to-submicron scale spatial structural properties of pup brain cells/tissues using light/photonic probes could provide a plethora of information in understanding the effects of fetal alcoholism. Aim: Using both light scattering and light localization techniques to probe alterations in nano- to-submicron scale mass density or refractive index fluctuations in brain cells/tissues of mice pups, exposed to fetal alcoholism. Approach: We use the mesoscopic physics-based dual spectroscopic imaging techniques, partial wave spectroscopy (PWS) and molecular-specific inverse participation ratio (IPR) using confocal imaging, to quantify structural alterations in brain tissues and chromatin/histone in brain cells, respectively, in 60 days postnatal mice pup brain, exposed to fetal alcoholism. Results: The finer focusing PWS analysis on tissues shows an increase in the degree of structural disorder strength in the pup brain tissues. Furthermore, results of the molecular-specific light localization IPR technique show an increase in the degree of spatial molecular mass density structural disorder in DNA and a decrease in the degree in histone. Conclusions: In particular, we characterize the spatial pup brain structures from the molecular to tissue levels and address the plausible reasons for such as mass density fluctuations in fetal alcoholism.

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We report the recently partial wave spectroscopy (PWS) with finner focusing that can probe precise scattering volume in tissues. Applications in distinguishing the nanostructural alteration in brain tissues in chronic alcoholism are reported.

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