Electrochemical Immunosensing of Cortisol in an Automated Microfluidic System Towards Point-of-Care Applications

This dissertation describes the development of a label-free, electrochemical immunosensing platform integrated into a low-cost microfluidic system for the sensitive, selective and accurate detection of cortisol, a steroid hormone co-related with many physiological disorders. Abnormal levels of cortisol is indicative of conditions such as Cushing’s syndrome, Addison’s disease, adrenal insufficiencies and more recently post-traumatic stress disorder (PTSD). Electrochemical detection of immuno-complex formation is utilized for the sensitive detection of Cortisol using Anti-Cortisol antibodies immobilized on sensing electrodes. Electrochemical detection techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have been utilized for the characterization and sensing of the label-free detection of Cortisol. The utilization of nanomaterial’s as the immobilizing matrix for Anti-cortisol antibodies that leads to improved sensor response has been explored. A hybrid nano-composite of Polyanaline-Ag/AgO film has been fabricated onto Au substrate using electrophoretic deposition for the preparation of electrochemical immunosening of cortisol. Using a conventional 3-electrode electrochemical cell, a linear sensing range of 1pM to 1µM at a sensitivity of 66µA/M and detection limit of 0.64pg/mL has been demonstrated for detection of cortisol. Alternately, a self-assembled monolayer (SAM) of dithiobis(succinimidylpropionte) (DTSP) has been fabricated for the modification of sensing electrode to immobilize with Anti-Cortisol antibodies. To increase the sensitivity at lower detection limit and to develop a point-of-care sensing platform, the DTSP-SAM has been fabricated on micromachined interdigitated microelectrodes (µIDE). Detection of cortisol is demonstrated at a sensitivity of 20.7µA/M and detection limit of 10pg/mL for a linear sensing range of 10pM to 200nM using the µIDE’s. A simple, low-cost microfluidic system is designed using low-temperature co-fired ceramics (LTCC) technology for the integration of the electrochemical cortisol immunosensor and automation of the immunoassay. For the first time, the non-specific adsorption of analyte on LTCC has been characterized for microfluidic applications. The design, fabrication technique and fluidic characterization of the immunoassay are presented. The DTSP-SAM based electrochemical immunosensor on µIDE is integrated into the LTCC microfluidic system and cortisol detection is achieved in the microfluidic system in a fully automated assay. The fully automated microfluidic immunosensor hold great promise for accurate, sensitive detection of cortisol in point-of-care applications.

The impact of selected factors in nurses' attitudes toward bedside computers

The purpose of this study was to determine the impact of selected factors on nurses' attitudes toward bedside computers. Bedside computer systems, also referred to as point-of-care systems, are clinical information systems that allow documentation of patient care and retrieval of data at the patient's bedside, or in close proximity to where care is delivered. The adoption of bedside computer systems appears to be increasing among U.S. institutions. As healthcare institutions undertake automation projects, they face many challenges associated with implementing large-scale change. ^ The study explored four factors and their relationship to nurses' attitudes toward bedside computers. A pre-bedside implementation survey of 184 staff nurses did not demonstrate a relationship between previous computer experience and nurses' attitudes toward bedside computers (p > .05). The data did not indicate a relationship between nurses' formal education and their attitude toward bedside computers (p > .05). The data did support a relationship between nurses' previous computer experience and their comfort in the use of bedside computers (p < .0005). Using a quasi-experimental control group design, attitudes of nurses were studied over an 18 month period. The Pre versus Post Survey data indicated that nurses who used bedside computers, the experimental group, had more positive attitudes than the nurses who did not use bedside computers, the control group (p < .0005). ^ The findings are significant to institutions implementing bedside computers, to the human resource development staff overseeing bedside computer training, and to the practice of clinical nursing. ^