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Polydimethylsiloxane: a new contrast material for localization of occult breast lesions

Background. The radioguided localization of occult breast lesions (ROLL) technique often utilizes iodinated radiographic contrast to assure that the local injection of 99mTc-MAA corresponds to the location of the lesion under investigation. However, for this application, this contrast has several shortcomings. The objective of this study was to evaluate the safety, effectiveness and technical feasibility of the use of polydimethylsiloxane (PDMS) as radiological contrast and tissue marker in ROLL.

Materials and methods. The safety assessment was performed by the acute toxicity study in Wistar rats (n = 50). The radiological analysis of breast tissue (n = 32) from patients undergoing reductive mammoplasty was used to verify the effectiveness of PDMS as contrast media. The technical feasibility was evaluated through the scintigraphic and histologic analysis.

Results. We found no toxic effects of PDMS for this use during the observational period. It has been demonstrated in human breast tissue that the average diameter of the tissue marked by PDMS was lower than when marked by the contrast medium (p <0.001). PDMS did not interfere with the scintigraphic uptake (p = 0.528) and there was no injury in histological processing of samples.

Conclusions. This study demonstrated not only the superiority of PDMS as radiological contrast in relation to the iodinated contrast, but also the technical feasibility for the same applicability in the ROLL.

Abstract

Although liquid-liquid extraction methods are currently being applied in many areas such as analytical chemistry, biochemical engineering, biochemistry, and biological applications, accessibility and usability of microfluidics in practical daily life fields are still bounded. Suspended microfluidic devices have the potential to lessen the obstacles, but the absence of robust design rules have hampered their usage. The primary objective of this work is to design and fabricate a microfluidic device to quantitatively monitor the drug uptake of cancer cells. Liquid-liquid extraction is used to quantify the drug uptake. In this research work, designs and simulations of two different microfluidic devices for carrying out multiplex solution experiments are proposed to test their efficiency. These simplified miniaturized chips would serve as suspended microfluidic metabolites extraction platform as it allows extracting the metabolites produced from the cancer cells as a result of applying a specific drug type for a certain period of time. These devices would be fabricated by making polydimethylsiloxane (PDMS) molds from the negative master mold using soft lithography. Furthermore, it can leverage to provide versatile functionalities like high throughput screening, cancer cell invasions, protein purification, and small molecules extractions. As per previous studies, PDMS has been depicting better stability with various solvents and has proved to be a reliable and cost effective material to be used for fabrication, though the sensitivity of the chip would be analyzed by cross contamination and of solvents within the channels of device.