The development of manufactured protein arrays is currently getting a lot of visibility due to the existence of an immense field of applications, including biosensors, diagnostics applications such as serum-based diagnostics, and pharmaceutical target design. The latter typically involves the study of protein targets through protein-protein interactions, enzyme-substrate reactions, receptor-ligand interactions, and drug-target binding. Protein microarrays can also be used to miniaturize and multiplex immunoassays and have performed better than enzyme-linked immunosorbent assays in both sensitivity and quantitative range for use in immunoassays.
A common operation in multiplexing is gridding proteins onto a substrate in an ordered array. Once arrayed, the substrate is probed with a fluorescent probe of interest, and is then analyzed to detect the locations where the probe bound to the substrate. An alternative to pin gridding, the most common means of achieving high-density arrays, is to use either BioJet Plus or Scienion for a non-contact dispense. Patented BioJet Plus technology involves the coupling of a microsolenoid valve to a high resolution syringe. The system is then synchronized with the XYZ motion allowing for very fast dispense with high accuracy and precision. Scienion dispensing is based on piezo technology that is also very fast. The Scienion technology dispenses from the picoliter range to the low nanoliter range, while the BioJet Plus technology dispenses from the low nanoliter range to the low microliter.
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BioDot's BioChip applications can be used for Fluorescent in situ hybridization (FISH). FISH is a research technique used to map specific genes or portions of genes in the cells of a person. This technique dates back 20 years when it was first introduced. It quickly became a preferred biological test, due to its wide applications, its focus on in situ studies and the ease with which it can be implemented. Since then, the technology has undergone various methodological maturations and modifications aimed at bettering it overall and, ultimately, making it superior. Today, the technique is characterized by low noise hybridization probes, quantitative analysis and multi-target visualizations.
The FISH technique is used to map out genes in cells. The principle of the technique is fairly simple and involves a DNA probe and target sequence. The DNA probe must be labeled either directly or indirectly with a reporter molecule before hybridization takes place. The probe and the target DNA sequence then undergo denaturing. Since the two are combined, complementary DNA sequences between the probe and the target sequence allow for annealing. The annealed sequences are extended to make them easier to visualize. In case where the DNA probe was labeled directly, the visualization process will be simple under a fluorescent microscope as the labeled sequence will be clearly visualized as it fluoresces. The FISH technique is very rapid, stable and easy to implement and as such very desirable.
Fluorescent in situ hybridization is applied in a wide variety of procedures in biomedical research. Due to its ability to map genes and chromosomes, it is successfully used to detect genetic disorders in children with unexplained developmental disabilities. Some of the diseases it diagnoses include Down Syndrome, Cri-du-chat and Prader-Willi Syndrome among many others.
FISH is also used in cancer research to diagnose the existence of cancer or evaluate its remission. This is usually done after removing tissue from area suspected to have cancer. The tissue are then assayed to determine the presence of cancerous genes such as the HER2 gene in breast cancer and in so doing form a diagnosis. Another application is in clinical studies to diagnose bacterial and viral infections. These species can be detected directly in patients sample suing the right marker.
At the time of its discovery, the FISH technique experienced major difficulties. There were no commercial hybridization kits and the fluorescent dyes available were few and unstable. Also, acquiring the probes was a problem and so was imaging as the fluorescent microscopes available then had poor objective and a lot of aberrations.
Recent developments have however refined his technique greatly making it one of the most accurate biomedical research techniques. Commercial kits and reagents are available, fluorescent dyes are more readily available and in many colors and fluorescent microscopes have become advanced eliminating chromatic aberrations. There is even imaging software for live cell imaging enabling multi target visualizations and also quantitative analysis. Suffice to say, the technique has become more affordable and widely available.
Tools which make diagnostics easy - using a mere single sample for analysis in various laboratory settings.
The use of assays was first introduced 50 years ago but it was just in 1995 that multiplexing was used. Since the development of multiplexing assays in the early 1990's several types of this analysis tool were developed. These assays were developed for clinical diagnostics so with just one sample multiple tests can be performed. The development of multiplexing assays resulted to faster analysis time, reduction of cost for labor and material and the reduction of need to harvest samples. The multiplexing assays have also made the availability of treatment faster.
There are several types of multiplexing assays. These assays are used to analyze a host of various things such as diagnosing a disease or researching a particular drug that for the cure of a disease. The 3 major types of multiplexing assays technologies are microarray technology, bead based technology and mass spectrometry. From these technologies these types of assays were born.
- Phage Display
- This type of multiplexing assay is used to probe the different interactions of protein. There are over 1010 possible protein and its interaction can be probed using the Phage Display. This type of multiplexing assay is typically used to generate antibodies. With just one Phage display 7,200 unique clones are yielded.
- Protein Arrays
- This type of multiplexing assay is used to analyze protein analyte. The thousand different types of proteins are analyzed using this array with the used of purified protein and high density protein chips. This assay helps reduce instrumentation cost and also simplifies the analysis.
- Bead-Based Arrays
- This type of multiplexing assay is the most commercially successful among the other types of assays. This multiplexing assay is used for laboratory testing like the testing for genotypes and allergen testing. It is also used for clinical diagnostics for diseases such as the infectious disease and autoimmune testing. It is also used to test the compatibility for organ transplant.
- Antibody Arrays
- This multiplexing assay use nitrocellose membranes for the quantification of proteins. This type of assay can also be scanned using commercially available DNA array scanners. Only the overhead light source DNA array scanners can be used to scan the antibody arrays.
- Bacterial Artificial Chromosome Arrays
- This type of multiplexing assay is used to diagnose cancer and birth defects. The bacterial artificial chromosome clones are what is analyzed to diagnose cancer and birth defects without the help of oligonucleotides.
This technology has allowed medical experts to make several diagnosis and analysis with just a single sample. There are several advantages of using multiplexing assays in both research and clinical settings. These benefits are:
- Time reduction
- The multiplexing assays help in reducing the analysis time. Unlike before where several testing has to be done at an interval, with the use of multiplexing assays several analysis can be made with just one sample. The result is that data can be provided easily. The data provided can help in swiftly diagnosing a disease, which in turn help start the treatment early.
- Less sample required
- Another benefit of using multiplexing assays is that a patient does not need to be harvested with a lot of sample for the diagnosis. With just one sample the battery of tests can already be performed. This means less blood harvesting, less pricking, less poking and less swathing. This also means less stress on the part of the patient.
- Reduction in labor
- The multiplexing assay can be used for different laboratory equipments. There is no need to keep changing sample trays so this means that a single person can do the work of several other persons. This also means that labor cost is cut off and the job is made more efficient.
- Reduction in assay cost
- With the multiplexing assay, you only have to buy one tray for several tests. You do not have to purchase a different tray for each laboratory testing. This reduces the cost of acquiring assays by more than half.
There are also several types of multiplexing assays depending on the type of tests that needs to be analyzed. The different types of multiplexing assays are Oligonucleotide Arrays, Second Generation Sequencing, Phage Display, Bacterial Artificial Chromosome Arrays, Protein Arrays, Bead Based Arrays, Antibody Arrays, Reverse Arrays, Mass Spectrometry, Quantitative PCR and Microplate Assays.
With each year the several types of multiplexing assays are developed making research and clinical diagnosis easier and allowing answers to other analytical needs to unfold.