The design and fabrication of nanoengineered platinum needles with laser welded carbon nanotubes (CNTs) for the electrochemical biosensing of cancer lymph nodes

Abstract

A new biosensor for detecting cancer involved sentinel lymph nodes has been developed via the electrochemical tracing of fatty acid oxidation as a distinct metabolism of malignant cells invading lymph nodes (LNs). The system included integrated platinum needle electrodes that were decorated by carbon nanotubes (as hydrophobic agents) through laser-assisted nanowelding. It was applied to record the dielectric spectroscopy data from LN contents via electrochemical impedance spectroscopy. The system was applied for dielectric spectroscopy of LN contents via electrochemical impedance approach. The reduced lipid content of involved LNs, due to fat metabolism by invasive cancer cells, would decrease the charge transfer resistance (R_CT) of the LNs with respect to their normal counterparts. Multi-walled carbon nanotubes (MWCNTs) with superhydrophobic properties were used to enhance the interaction of Pt needle electrodes with the lipidic contents of lymph nodes. This is the first time that a fatty acid metabolism-based sensing approach has been introduced to detect involved LNs. Moreover, a novel electrode decorating method was applied to enhance the interfacial contact of this lipid detection probe (LDP). In order to avoid doubt about the biocompatibility of ferrocyanide, [Fe(CN)₆]⁴⁻ and ferricyanide, [Fe(CN)₆]³⁻, a biocompatible injectable metal ion-based material, ferric carboxymaltose, was selected and applied as the electrolyte for the first time. Rabbit LNs were tested using the LDP in the animal model phase. The system was then used in vitro on 122 dissected human LNs in the operating room. Calibration of the results showed an excellent match between the dielectric response of the LDP (known as charge transfer resistance (R_CT)) and the final pathological diagnoses. The LDP may have a promising future after further clinical investigations for intra-operative distinction between normal and cancerous LNs.