  Biolasers made of biological materials have attracted a great of research
attention due to their biocompatibility and biodegradability, which have the
potential for biosensors and biointegration. However, the current fabrication
method of biolasers suffers several limitations such as complicated processes,
time-consuming and environmental unfriendly. In this work, a novel approach
with green processes for fabricating solid-state microspheres biolasers is
demonstrated. By using dehydration via a modified MicroglassificationTM
technology, dye-doped bovine serum albumin (BSA) droplets can quickly (less
than 10 minutes) and easily turn into solid microspheres with the diameter
ranging from 10-150 {\mu}m. The size of the microspheres can be effectively
controlled by changing either the concentration of BSA solution or the diameter
of the initial droplets. Fabricated microspheres can act as efficient
microlasers under optical pulse excitation. Lasing threshold of 7.8 {\mu}J mm-2
and quality (Q) factor of about 1700 to 3100 are obtained. The size-dependence
of lasing characteristics have been investigated and the results show a good
agreement with whispering gallery mode (WGM) theory. Our finding contributes an
effective technique for the fabrication of high Q factor microlasers that may
be potential for applications in biological and chemical sensors.
