A PVAc-Based Benzophenone-8 Filter as an Alternative to Commercially Available Dichroic Filters for Monitoring Calcium Activity in Live Neurons via Fura-2 AM

In this paper, we design, fabricate, and test a PVAc-based benzophenone-8 (PVAcB-8) emission filter to monitor calcium changes in live neurons. We loaded neurons with fura-2 AM, a calcium-sensitive fluorescent dye, which has dual excitation wavelengths at 340 nm, 380 nm with ratiometric emission at 510 nm. To attenuate excitation wavelengths in the UV region and transmit emission light at 510 nm, benzophenone-8 absorption dye was selected as it exhibits high attenuation across 300 to 400 nm. Measurements on the PVAcB-8 filter revealed an attenuation of approximately two and a half orders of magnitude, which is sufficient to collect fluorescence signal from fura-2 AM loaded neurons. The PVAcB-8 filter was compared with a commercially available dichroic filter and proven more efficient in fluorescent imaging.