Microplate Reader Purchasing Guide

Fundamental to a wide range of applications including drug discovery, proteomics, and bioassay validation, microplate readers detect chemical, physical, or biological activities of samples through measurement of light. These lab benchtop essentials assist researchers in quantifying chemical reactions through a range of light detection methods. With the ability to also screen not just microplates but also test tubes and cuvettes. Plate readers can offer parallel processing of small sample volumes for enzyme-linked immunoabsorbent assays (ELISAs), NADH quantitation, and protein-protein interaction detection. It's very common for these instruments to be used for manufacturing processes in biotechnology or pharmaceutical industries and can be found in many academic research labs.

Obtaining useful information and consistent results from your experiments and research call for usage of reliable instruments. With a wide range of microplate readers featuring varied detection methods to choose from, deciding on what unit to get for your application can be an intimidating and overwhelming task. To help you get started, Laboratory App has put together this simple guide with key points to consider when purchasing the right Microplate Reader for your application.

Application Demands for Your Microplate Reader Purchase

Finding the perfect plate reader unit for your laboratory ultimately depends on the application it will be used for. Knowing what your application demands from you and visualizing the future direction of your studies can narrow down the plethora of plate reader options available. You can start by answering these questions:

What wavelength (nm) and read mode/s does your application require?

This will depend on the type of samples and assays you will be working on. The most common modes include absorbance, luminescence, fluorescence, time-resolved fluorescence, and fluorescence polarization. These are briefly explained below:

Absorbance

Absorbance detection works with a light source illuminating samples using a particular wavelength and a light detector on the other side of the well measuring transmission of the initial light to the sample. How much light transmitted can usually be related to concentrations of molecules being studied, making absorbance detection good for ELISA assays, enzyme activity assays or protein and nucleic acid quantification assays.

Luminiscence

Resulting from a chemical or biochemical reaction, luminescence detection does not require a light source for excitation. With an optical system consisting of a light-tight reading chamber and a photomultiplier tube (PMT), luminescence detection is typically used for applications such as cell viability, cytotoxicity, and biorhythm assays.

Fluorescence

Fluorescence detection may be more expensive compared to absorbance detection because of its instrumentation, however it reaches a broader range of applications. Consisting of an excitation system that illuminates the sample with a specific wavelength, an emission system that captures emitted light by the sample and separates it from the excitation light, while a PMT that measures signals, fluorescence detection offers better sensitivity compared to absorbance detection.

Time-Resolved Fluorescence

Compared to Fluorescence Intensity (FI) detection with standard fluorescent dyes that emit light right after excitation, Time-Resolved Fluorescence (TRF) make use of specific fluorescent molecules, known as lathanides, that emit light over long periods of time after excitation. With the ability to excite lathanides through a pulsed light source and measure these after the excitation pulse, lower measurement backgrounds compared to standard FI assays can be achieved. TRF is usually used in drug screening applications.

Fluorescence Polarization

Fluorescence Polarization (FP) differs with FI detection when it comes to its optical system, with FP having polarizing filters found on the light path. In contrast to FI and TRF, this type of detection have samples in the microplate excited by polarized light. Polarization of light emitted is reliant on the mobility of fluorescent molecules found in the wells. Through polarizing filters, emission system of plate readers are able to analyze polarity of emitted light. Small fluorescent molecules moving freely in a sample would have a low level of polarization, while fluorescent attached to large molecules would mean high level of polarization. FP is typically used in molecular binding assays.

If your laboratory performs routine analysis and runs the same samples and assays, you can go for more economical single-function readers. However, if you want greater flexibility because your samples and assays require changes from sample to sample, it is better to opt for multi-mode readers capable of using a combination or all of your needed detection modes.

What kind of detection technology do you prefer?

With a monochromator, users can indicate any wavelength requirement and cutoffs to perform particular excitation or emission, providing convenient spectral scanning and better flexibility. Filter-based detection on the other hand offers precise sensitivity and allow for fast switching between specific wavelengths for kinetic assays.

How much flexibility do you need?

Consider your present and future applications before getting a microplate reader. If you see your lab needing capability upgrades in the years to come, ensure that the unit you are getting is expandable and see additional options available for it.

Will you be using test tubes, cuvettes, or microplates?

How many wells will your microplate have?

Always check if your available supplies and equipment match. If you will be working on high throughput applications, make sure you procure a reader that can accommodate you a range of plates.

Check if your Samples are Temperature or Agitation Sensitive

Configurations of your microplate reader would also depend on your samples. Check to see if your samples require temperature control and agitation, or not. If you have samples that need constant temperature and mixing, search for units with shaker and temperature control functionalities. Plate readers with heating and cooling functions are often used to enable specific enzymatic and growth assays.

Decide How You Want Data to be Reviewed and Manipulated

If you prefer recording and analyzing your data in situ, go for integrated plate reader systems that can be integrated to full robotic mechanism and can easily be adjusted based on your sample handling requirements. 

Check if the unit you will be getting comes with a user-friendly software, if it allows addition of pre-programmed and custom protocols, what analysis can it offer, and how it exports data. Bear in mind though that the range of applications and analysis types under this option may be more limited. Setting up your microplate reader to an external PC system on the other hand may offer more options when it come to data analysis and manipulation. For powerful and comprehensive data analysis and management, you may want to take a look at plate readers with preinstalled software.

Assess Lab Space where the Microplate Reader will be Situated

Keep in mind your available lab space when looking for a microplate reader as this can determine the convenience of location and accessibility of the equipment. For those with an open and large area, you can get a unit that comes with a separate PC, keyboard and mouse -- compared to those that only come with an LCD screen. You can also search for modular units that can be integrated or you can go for different dedicated units for each detection mode you need.

Review and Decide on Budget Allocations for your Microplate Reader

If you have ample funding, you can always get new microplate readers for your assay development, cell biology, PCR setup, and stem cell research applications. For those with a tighter budget, no need to sweat as there are a number of alternatives you can go for like purchasing used or fully certified to factory specifications microplate readers. You may also want to acquire some modules now and do upgrades on a later period. While most Original Equipment Manufacturers (OEMs) may take time in supplying new lab instruments, a trusted used equipment distributor carries easily available and value-priced microplate readers best for urgent unit replacement needs, backups, or to meet high market demands. 

Acquainting yourself with these key factors before buying a plate reader can help you find the most suitable unit to fit your application and laboratory demands. If you are having trouble picking out the appropriate instrument for your applications, you can always depend on effective solutions and advice from industry experts.