Biosensors and Bioelectronics 21 (2006) 1210–1218 Fiber-optic biosensor to assess circulating phagocyte activity by chemiluminescence Moni Magrisso a , Ohad Etzion c , Greg Pilch d , Alex Novodvoretz a , Galit Perez-Avraham c , Francisc Schlaeffer c , Robert Marks a,b,∗ a National Institute for Biotechnology in The Negev, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel b Department of Biotechnology Engineering, Ben-Gurion University of The Negev, P.O. Box 653, Beer-Sheva 84105, Israel c Department of Internal Medicine E, Soroka University Medical Center, P.O. Box, Beer-Sheva 84105, Israel d Department of Industrial Engineering & Management, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel Received 8 March 2005; received in revised form 5 May 2005; accepted 6 May 2005 Available online 22 June 2005 Abstract We describe herein the construction of a novel computerized multi-sample temperature-controlled luminometer for a fiber array-based biosensor to monitor circulating phagocyte activity. It can perform simultaneously integral measurements of chemiluminescence emitted from up to six samples containing less than 0.5 l whole blood while the samples and detector do not change their position during the measurement cycle. The optical fibers in this luminometer are used as both light guides and solid phase sample holders. The latter feature of the instrument design simplifies the assessment process of both the extra-cellular and the intra-cellular parts of the phagocyte-emitted chemiluminescence using the same system. We describe some examples or proof of principle for the use of the biosensor. This new technology may find use in a wide range of analytical luminescence applications in biology, biophysics, biochemistry, toxicology and clinical medicine. © 2005 Elsevier B.V. All rights reserved. Keywords: Fiber-optics; Blood; Phagocyte; Biosensor; Luminometer; Chemiluminescence 1. Introduction Professional phagocytes, such as polymorphonuclear neu- trophil granulocytes (PMNs), kill invading bacteria, and for this purpose they are equipped with bactericidal weapons that involve both oxygen-dependent and oxygen-independent mechanisms. Activation of the oxygen-dependent mecha- nisms leads to the production of superoxide anion and hydrogen peroxide. In addition, there is a release of gran- ule contents and reactive oxygen species (ROS) from PMNs Abbreviations: CFU, colony forming units; CL, chemiluminescence; fMLP, n-formyl-methionyl-leucyl-phenylalanine; KRP, Krebs-Ringer phos- phate medium; NA, numerical aperture; OZ, opsonized zymosan; PLC, programmable logic controller; PMNs, polymorphonuclear neutrophil gran- ulocytes; PMT, photomultiplier tube; ROS, reactive oxygen species; UTI, urinary tract infections ∗ Corresponding author. Tel.: +972 8 6909244; fax: +972 8 6472857. E-mail address: rsmarks@bgu.ac.il (R. Marks). (Weis and LuBuglio, 1980), causing injury to the surround- ing tissues. Thus, tissue damage following many bacterial infections is not only caused by bacterial virulence factors, but also by different host defense mechanisms (Lock et al., 1990). Chemiluminescence (CL) is a by-product of the com- plex cellular metabolic activity of PMNs and it is directly associated with the generation of oxidative species involved in the bactericidal activity of PMNs (Hosker et al., 1989). This implies that one can follow such phagocyte activities by monitoring their CL intensity. The most productive way to work with living phagocytes is to keep them in their whole blood environment. This min- imizes the need for laborious work and helps prevent the introduction of artifacts when using cell purification method- ologies (Glasser and Fiederlein, 1990). In addition, it reduces the time required for each test and maintains conditions that are close to in vivo cellular environment. The sample vol- ume required for analysis using this method is very small 0956-5663/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2005.05.006