Phosphor Imaging

Introduction

While fluorescent and chemiluminescent imaging techniques and their detectors are becoming more sensitive and selective, photostimulated luminescence from phosphor storage plates remains a key application for many researchers, especially for applications such as electrophoretic mobility shift assays (EMSA), enzyme assays, and in-vivo imaging.

Phosphor imaging is a method to detect radioactive material in applications such as Northern, Southern, or Western blotting, or in radiolabeled tissue sections. Phosphor imaging has many benefits over autoradiography to detect radio labels using x-ray film, including increased sensitivity, shorter exposure times, and a greater dynamic range than is possible with film.

In phosphor imaging, a storage phosphor screen captures the energy from the radioactive material. The storage screen contains a thin layer of crystals that absorb and store energy emitted by radioactive material. The storage screen is exposed to a radioactive sample, such as a blot or tissue section. After the exposure, the screen is imaged by scanning with a laser. The laser converts the stored energy to visible light which can be captured using a digital imaging system. The emitted light is proportional to the amount of radioactivity present in the original sample, making phosphor imaging excellent for quantitative comparisons. The Figures below demonstrate the linearity and wide dynamic range possible with phosphor imaging.

The phosphor screen can be erased by exposure to white light and re-used.

The Azure Sapphire Biomolecular Imager includes phosphor imaging among its available imaging modalities. Azure also provides an imaging plate eraser to ensure quick, complete erasure of imaging screens to maximize data and image quality.

Traditional phosphor imagers are often single function and require a large footprint. The Azure Sapphire offers the ability to scan storage phosphor screens for filmless autoradiography, with exceptional dynamic range and image quality thanks to the use of laser excitation and photon multiplier tube (PMT) detection. The Sapphire also incorporates exceptional visible fluorescent and near infra-red scanning along with true chemiluminescent and white light imaging making it a true lab workhorse.

Materials and Methods
Sample Preparation

An American Radiolabeled Chemicals 14C standard with slices from 1000 to 0.004 μCi/g was exposed to a BAS-MS storage phosphor screen (0.9 DPM/mm2/hr sensitivity) for 3 hours.

Storage Phosphor Plate Imaging

Following exposure, the storage phosphor screen was imaged using the Phosphor Imaging module of the Sapphire with standard excitation and detection settings. Samples were quantified and limits of detection (LOD) and dynamic range (DR) calculated.

Results and Conclusions

The Sapphire Biomolecular Imager captures high-quality images with a large dynamic range from standard storage phosphor screens (Figure 1). Following sample quantification using AzureSpot analysis software, the LOD for American Radiolabeled Chemicals 14C standard after a 3-hour exposure was determined to be 0.036 μCi/g. Furthermore, a highly linear dynamic range from 1000 to 0.036 μCi/g was observed (r2 = 0.99 [Figure 2]).

To conclude, the Sapphire is capable of imaging storage phosphor screens producing high quality images for later quantification; while also offering the ability to rapidly image fluorescent, chemiluminescent and NIR samples all within a single compact footprint.

Materials and Product Numbers
Related Products

Laser and CCD based scanning system for blots, gels and more

Erasing storage phosphor screens made easy.

Looking for a full list of applications?

Documents

Document TypeDescription
Application NotePhosphor Imaging with the Sapphire Biomolecular ImagerDOWNLOAD

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