Production of local microbubbles (MBs) with dense distribution in tumor environment is achieved by developing an integrated electrochemical stimulator on a microfabricated silicon needle covered by zinc‐oxide nanowires (ZnONWs). MBs are then exploded by external ultrasonic actuation, which induce microcavitations in tumor cells followed by direct entrance of anticancer drugs into cancer cells. This system, named ZnO nanowire‐based microbubble generator probe (ZnONW‐MGP), is tested on tumorized mice models (by MC4L2 breast cell lines). Mice treated by ZnONW‐MGP have ≈82% reduction in tumor size within 10 days with just 25% of conventional dose of paclitaxel while in the absence of the system, they have just a 15% reduction in tumor size. Presence of ZnO nanostructures on microneedles strongly reduces the size of MBs and enhances the efficacy of the sonoporation.
Background
Nodal status evaluation is a crucial step in determining prognostic factors and managing treatment strategies for breast cancer patients. Preoperative (CNB), intraoperative (SLNB), and even postoperative techniques (Formalin-Fixed Paraffin-Embedded sectioning, FFPE) have definite limitations of precision or sometimes are time-consuming for the result declaration. The primary purpose of this prospective study is to provide a precise complementary system for distinguishing lymph nodes (LNs) involved by cancerous cells in breast cancer patients intraoperatively.
Methods
The proposed system, Electrical Lymph Scoring(ELS), is designed based on the dielectric properties of the under-test LNs. The system has a needle-shaped 2-electrode probe entered into SLNs or ALNs dissected from patients through standard surgical guidelines. Impedance magnitude in f = 1 kH (Z1kHz) and Impedance Phase Slope in frequency ranges of 100 kHz–500 kHz (IPS) were then extracted from the impedance spectroscopy data in a cohort study of 77 breast cancer patients(totally 282 dissected LNs) who had been undergone surgery before (n = 55) or after (n = 22) chemical therapies (non-neoadjuvant or neoadjuvant chemotherapy). A new admittance parameterSymbol also proposed for LN detection in neoadjuvant chemotherapy patients.
Results
Considering the permanent pathology result as the gold standard checked by two independent expert pathologists, a significant correlation was observed between the presence of cancerous cells in LNs and individual ranges of the ELS electrical responses. Compared with normal LNs containing fatty ambient and immune cells, LNs involved by cancerous clusters would reduce the Z1kHz and increase the IPS. These changes correlate with fat metabolism by cancer cells due to their Fatty Acid Oxidation (FAO) in LN, which results in different dielectric properties between high and low-fat content of normal and cancerous LNs, respectively.
Conclusions
By finding the best correlation between our defined impedimetric parameters and pathological states of tested LNs, a real-time intraoperative detection approach was developed for highly-sensitive (92%, P<0.001) diagnosis of involved sentinel or axillary LNs. The impact of real-time intraoperative scoring of SLNs would make a pre-estimation about the necessity of excising further LNs to help the surgeon for less invasive surgery, especially in the absence of frozen-section equipment.
Graphical abstract
Highlights
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