Nanocarbon materials, including single-walled carbon nanotubes (SWCNTs) and graphene, promise various novel biomedical applications (e.g., nanoelectronic biosensing). In this Letter, we study the ability of SWCNT networks and reduced graphene oxide (rGO) films in interfacing several types of cells, such as neuroendocrine PC12 cells, oligodendroglia cells, and osteoblasts. It was found that rGO is biocompatible with all these cell types, whereas the SWCNT network is inhibitory to the proliferation, viability, and neuritegenesis of PC12 cells, and the proliferation of osteoblasts. These observations could be attributed to the distinct nanotopographic features of these two kinds of nanocarbon substrates.

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Formation of blood clots, called thrombus, can happen due to hyper-coagulation of blood. Thrombi, while moving through blood vessels can impede blood flow, an important criterion for many critical diseases like deep vein thrombosis and heart attacks. Understanding mechanical properties of clot formation is vital for assessment of severity of thrombosis and proper treatment. However, biomechanics of thrombus is less known to clinicians and not very well investigated. Photoacoustic (PA) spectral response, a non-invasive technique, is proposed to investigate the mechanism of formation of blood clots through elasticity and also differentiate clots from blood. Distinct shift (increase in frequency) of the PA response dominant frequency during clot formation is reported. In addition, quantitative differentiation of blood clots from blood has been achieved through parameters like dominant frequency and spectral energy of PA spectral response. Nearly twofold increases in dominant frequency in blood clots compared to blood were found in the PA spectral response. Significant changes in energy also help in quantitatively differentiating clots from blood, in the blood. Our results reveal that increase in density during clot formation is reflected in the PA spectral response, a significant step towards understanding the mechanobiology of thrombus formation. Hence, the proposed tool, in addition to detecting thrombus formation, could reveal mechanical properties of the sample through quantitative photoacoustic spectral parameters.

Thyroid nodule (TN), a discrete palpable swelling of the thyroid gland, is prevalent among 8% of the adult population. The important concern with these nodules is the differentiation between benign and malignant ones. Since conventional diagnostic techniques (e.g., ultrasound) are not accurate in diagnosis, clinical surgeons adopt to excision biopsy, a golden standard, which requires surgery and removal of the gland. We propose to apply Photoacoustic Spectral Response (PASR), a non-invasive and elasticity based diagnostic technique, onto TN for malignancy diagnosis. In this study, time domain photoacoustic signals were acquired through custom built experimental setup inside the surgical theatre and spectral information were obtained through signal processing. PA spectra could distinguish Follicular Variant of Papillary Thyroid Carcinoma (a thyroid cancer) from the other tissues with a high accuracy which an important challenge in conventional diagnostic techniques. Further, other tissue variants were also successfully differentiated through signal decomposition in a quantitative manner.

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