Free space whispering gallery mode microlasers as highly sensitive biosensors

¹ National Research Council - Institute for Complex Systems (CNR-ISC), c/o Department of Physics, University “La Sapienza”, Rome, Italy
² Department of Physical and Chemical Sciences, University of L’Aquila, L’Aquila, Italy
³ Istituto Nazionale di Genetica Molecolare INGM “Romeo ed Enrica Invernizzi”, Milan, Italy
⁴ Dipartimento di Scienze Biochimiche “A. Rossi Fanelli”, University “La Sapienza”, Rome, Italy
⁵ Department of Physics, University “La Sapienza”, Rome, Italy
⁶ National Research Council - Institute of Nanotechnology (CNR-Nanotec), c/o Department of Physics, University “La Sapienza”, Rome, Italy
⁷ National Research Council - Institute for Biomedical Technologies (CNR-ITB), Milan, Italy
⁸ Department of Medical Surgical Sciences and Biotechnologies, University “La Sapienza”, Rome, Italy

^* Corresponding author: s.stefanoferretti@gmail.com

Published online: 31 October 2024

Abstract

High-precision biosensors for single or few molecules detection play a central role in numerous key fields, such as environmental monitoring and healthcare for early-stage disease diagnosis. In the last decade, laser biosensors have been investigated as proofs of concept, and several technologies have been proposed. Here we propose a demonstration of polymeric whispering gallery microlasers as biosensors for detecting proteins at low concentrations. Free space microlasers have the great advantage of working without any need for waveguiding for input excitation or output signal detection. The photonic microsensors can be easily patterned on microscope slides and operate in air and solution. We could detect down to 400 pg of protein without specific binding, and few tens of pg/mL with specific binding.