Molecular labels
Many types of nucleic acids require a secondary detection technology, e.g. a label, because a nucleic acid does not have intrinsic properties that are useful for direct high-sensitivity detection. Reasons for ultrasensitive nucleic acid detection include analysis of genetic material from single cells and single copy gene detection. Molecular labels provide the means for detecting and evaluating most biological interactions, such as those involving DNA, proteins, whole cells and pathogens. Currently available technologies have limited sensitivity and efficacy. Desirable characteristics of a label are stability, sensitivity of detection, speed and convenience of detection and low cost. No ideal label fulfilling all of these properties is available as yet. Better labels or detection reactions may enable an assay that requires fewer amplification cycles and eliminates the need for PCR. A selection of molecular labels and technologies for their detection are available. Nanoparticle technologies for molecular labeling will be described in later chapters. To make DNA technology attainable for routine diagnostics, several non-radioactive alternatives have been developed.
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