Nanoparticle labels/immunosensors

G. Liu and Y. Lin, Electrochemical magnetic immunosensor based on gold nanoparticle labels. J. Nanosci. Nanotech. 5, 1060-1065 (2005). 

Labeled immunosensors typically make use of a reporter molecule attached to the respective antibody. Apart from the electrochemical detection schemes discussed below, immunosensors employ fluorescent labels, radioactive labels, or nanoparticles, among other reporter systems [407—410]. Labeled immunosensors normally operate using either a direct or indirect sandwich procedure or a competitive format as depicted in Figure 1.18. 

Label-free impedance immunosensors have been developed, but in general these methods may require additional amplification to improve sensitivity [57,58]. Nevertheless, a capacitance method using a ferri/ferrocyanide probe and a potentiostatic step approach gave DL 10 pg mL (500 fM) for lL-6 in buffer [59]. Optimization of experimental protocols in flow injection impedance spectroscopy led to sensitivity in the low aM range for interferon-y in buffer [60]. Sensitivities have been enhanced using metal nanoparticle labels or AuNP labels that catalyze subsequent Ag deposition [57]. These methods may be promising for future point-of-care applications if NSB from non-analyte proteins in the patient samples can be minimized. 

Yang, X., Yuan, R., Chai, Y., Zhuo, Y., Mao, L., Yuan, S. Ru(bpy)3-doped silica nanoparticles labeling (ot a sandwich-type electrochemiluminescence immunosensor. Biosensors and Bioelectronics 25, 1851-1855 (2010)... 

This book provides a comprehensive compilation of seven chapters, with important contributions of several authors. Chapter 1 reviews the recent research in using nanoparticle labels and multiplexed detection in protein immunosensors. This chapter summarizes recent progress in development of ultrasensitive electrochemical devices to measure cancer biomarker proteins, with emphasis on the use of nanoparticles and nanostmctured sensors aimed for use in clinical cancer diagnostics. Based on recent strategies focused on nanomaterials for electrochemical biosensors development. Chap. 2 discusses the development of new... 

Tang, J., B. Su, D. Tang, and G. Chen. 2010. Conductive carbon nanoparticles-based electrochemical immunosensor with enhanced sensitivity for a-fetoprotein using irregular-shaped gold nanoparticles-labeled enzyme-linked antibodies as signal improvement. Biosens. Bioelectron. 25 2657-2662. 

Our work deals with only a few examples (i) the immunosensor for the forest-spring encephalitis diagnosis (a metal label is used for signal generation), (ii) the enzyme-free urea sensor and (iii) the platinum sensor for antioxidant activity determination. What they all have in common is a screen-printed transducer consisting of graphite or Pt nanoparticles. Transducer configuration is shown in Fig. 27.1. 

Valera, E., J. Ramdn-Azcon, FJ. Sanchez, et al. 2008. Conductimetric immunosensor for atrazine detection based on antibodies labelled with gold nanoparticles. Sens. Actuat. It Chem. 134 95-103. 

A model immunosensor based on a labeling method using gold nanoparticles (AuNPs) and electrochemical detection is developed. Microparamagnetic beads (MB) as primary antibody immobilization platforms and AuNPs modified with a secondary antibody as high sensible electrochemical labels have been used. The carbon electrode used as transducer incorporates a magnet that allows the collection/ immobilization on its surface of the immunological sandwich attached to the MB. 

---