Real-time Thermal Cycler (qPCR)

Discover the qTOWER iris product family of real-time PCR thermal cyclers. Get the fastetst and most reliable real-time PCR results for your application.

Fully automated real-time PCR devices for robotic workflow setups support you in streamlining your application even further.

Quantitative PCR with real-time thermal cyclers

Quantitative PCR (qPCR), also known as real-time PCR, is an essential method in modern molecular biology. This method precisely quantifies nucleic acids such as DNA and RNA. It is ubiquitous today in medical diagnostics labs, biotech research, and pharmaceutical labs.

One of the key advantages of real-time PCR when compared to traditional endpoint PCR is its real-time monitoring capability. With qPCR, the DNA amplification process can be measured in real time, enabling precise calculation of the starting concentration of a sample. This advantage makes qPCR a perfect fit for applications such as measuring viral loads for diagnostic purposes or detecting pathogens in the food industry. 

Basics of real-time PCR / qPCR

Real-time PCR builds on the polymerase chain reaction (PCR), in which DNA or RNA sequences are amplified through cycles of precise heating and cooling. The PCR method essentially copies minute traces of nucleic acids and amplifies them exponentially, thus making them useful for analysis. However, the traditional endpoint PCR method does not provide any clues about the quantity of DNA or RNA during the process: Only once the procedure is complete can you view the amplification result using gel electrophoresis. 

This is where qPCR comes in: By using fluorescent markers that bind to the DNA in the amplification process, the user gains insight into the amount of nucleic acid while the process is still running. The fluorescence increases in proportion to the amount of amplified product. This makes it possible to measure the quantity of nucleic acid. Thus, qPCR provides not just qualitative information, but quantitative information — something incredibly valuable when detecting viruses or bacteria in medical diagnostics, for example.

Sidebar: The history of qPCR

The development of quantitative PCR traces back to the original discovery of the polymerase chain reaction (PCR) by Kary Mullis in 1983. This revolutionary technology enabled us to amplify DNA in a way previously unthinkable. In the 1990s, PCR evolved into qPCR with the introduction of fluorescence techniques for real-time monitoring of the amplification process. Now, labs could not only detect DNA amplification, they could also measure the exact amount of starting DNA. This development ushered in a paradigm shift in molecular diagnostics and made qPCR an indispensable tool in modern research and diagnostics.

The qPCR process in detail

The qPCR process is based on the principle of traditional endpoint PCR. It has three main steps: Denaturation, Annealing, and Elongation.

1. Denaturation: In this first step, the double-stranded DNA is heated to about 94-98 °C (201-208 °F) to split it into single strands. This opens up access for the primer that will bind to the individual strands in the next step.
2. Annealing: At a temperature of 50-65 °C (122-149 °F), specific primers bind to the complementary regions on the single DNA strands. These primers serve as the starting point for the polymerase, which will synthesize the DNA in the next step.
3. Elongation: The temperature is increased to approx. 72 °C (162 °F) to promote taq polymerase activity. This enzyme elongates the DNA strand by binding free nucleotides to the primer and creating a new, complementary strand. Since the taq polymerase takes effect again in each new cycle, the DNA amount also doubles each cycle.

With qPCR, this process takes place in a real-time thermal cycler. The real-time thermal cycler precisely controls the temperature in defined cycles while reading the fluorescent signals released when the target DNA is amplified. The fluorescence intensity is directly proportional to the growing amount of amplified DNA, ultimately making it possible to measure the nucleic acid concentration of the starting sample.

qPCR thermal cyclers: What's inside

The real-time thermal cycler, also known as a qPCR thermal cycler, is the core machine responsible for the qPCR process. It controls the temperature cycles for denaturation, annealing and elongation. It simultaneously enables real-time detection of the amplification products. A typical qPCR thermal cycler consists of the following main components:

1. Thermal cycling block: The thermal cycling block holds samples and is responsible for precise temperature regulation. Depending on the thermal cycler model, every sample has a volume between 5 and 100 µl; samples are placed in a small reaction vessel in the thermal cycling block.
2. Optical system: The optical detection system records the fluorescence produced during the amplification phase. The machine makes these measurements in real time. They are crucial for the quantitative analysis of nucleic acids.
3. Software: The thermal cycler's software is responsible for orchestrating the whole process. It analyzes the fluorescence data to calculate the concentration of nucleic acids in the sample. The analysis often relies on measuring the so-called Ct (cycle threshold) value, which represents the cycle where the fluorescent signal exceeds the background level.

Modern qPCR thermal cyclers offer high precision, rapid cycle times, and the capability to analyze numerous samples at once.

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Applications and target industries

qPCR has become established in many applications, thanks to its precision and reliability. Key fields include:

1. Medical diagnostics: In clinical diagnostics, qPCR is used to identify and quantify pathogens such as viruses, bacteria and fungi. Most notably, qPCR played a central role in the COVID-19 pandemic when it came to detecting the SARS-CoV-2 virus.
2. Oncology: In cancer research and diagnostics, qPCR is employed to detect mutations in cancer genes and to quantify the expression of tumor markers.
3. Forensics: In forensic science, qPCR is used to analyze DNA samples found at crime scenes. It can help determine a suspect's identity or deliver clues in criminal investigations.
4. Foodstuffs and environmental science: In the food industry as well as in the environmental industry, qPCR is used to detect carcinogens in food and water, as well as to ensure the quality of manufactured products.
5. Research: In pure research, qPCR is used to investigate gene expression, gene transfer, and genetic modifications. qPCR enables us to precisely analyze the activity of specific genes in different biological systems.

qPCR with cutting-edge real-time thermal cyclers from Analytik Jena

With the qTOWER iris and the qTOWER auto Series, Analytik Jena offers high-performance qPCR thermal cyclers that boast not only superior temperature and measurement precision, but also a wide spectrum of applications.  The massive selection of consumables, assays and dye modules enables laboratories to design versatile and flexible qPCR operations, while uncompromising mechanical components and whisper-quiet operation round out the advantages of Analytik Jena's qPCR thermal cyclers.