Microelectrochemical Smart Needle for Real Time Minimally Invasive Oximetry.

Daniela Vieira,Evan Dimentberg,Geraldine Merle,Francis Mceachern,Romina Filippelli,Edward J Harvey

doi:10.3390/bios10110157

Abstract

A variety of brain disorders such as neural injury, brain dysfunction, vascular malformation, and neurodegenerative diseases are associated with abnormal levels of oxygen. Current methods to directly monitor tissue oxygenation in the brain are expensive and invasive, suffering from a lack of accuracy. Electrochemical detection has been used as an invasiveness and cost-effectiveness method, minimizing pain, discomfort, and injury to the patient. In this work, we developed a minimally invasive needle-sensor with a high surface area to monitor O2 levels in the brain using acupuncture needles. The approach was to directly etch the iron from stainless steel acupuncture needles via a controlled pitting corrosion process, obtaining a high microporous surface area. In order to increase the conductivity and selectivity, we designed and applied for the first time a low-cost coating process using non-toxic chemicals to deposit high surface area carbon nanoparticle, catalytically active laccase, and biocompatible polypyrrole. The physicochemical properties of the materials were characterized as well as their efficacy and viability as probes for the electrochemical detection of PO2. Our modified needles exhibited efficient electrocatalysis and high selectivity toward O2, with excellent repeatability. We well engineered a small diagnostic tool to monitor PO2, minimally invasive, able to monitor real-time O2 in vivo complex environments.

Highlights

IntroductionOxygen concentration is important for viability in certain tissues such as the brain
Oxygen plays a critical role in physiological and pathological processes
A linear linear fit fit was was given by current density = −0.4887 * O2 concentration −2.2026 over the oxygen range, which demonstrates a sensitivity of −0.49 μA cm−2 per % PO2 of the sensor

Summary

Introduction

Oxygen concentration is important for viability in certain tissues such as the brain. It has been well established that neurons in the brain are strongly affected by low levels of oxygen causing detrimental outcomes within minutes [4]. Current methods to directly monitor tissue oxygenation in the brain are varied. Non-invasive methods include functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), and near-infrared spectroscopy. These are expensive imaging techniques that allow for an overview, but have poor resolution, and suffer from a lack of accuracy as well as require transfer and even anesthesia of the patient [1,2,5]. Other direct techniques are invasive with the insertion of electrodes or probes.

Methods

Discussion

Conclusion