Protein-Based Three-Dimensional Whispering-Gallery-Mode Micro-Lasers with Stimulus-Responsiveness

Abstract

For the first time, proteins, a promising biocompatible and functionality-designable biomacromolecule material, acted as the host material to construct three-dimensional (3D) whispering-gallery-mode (WGM) microlasers by multiphoton femtosecond laser direct writing (FsLDW). Protein/Rhodamine B (RhB) composite biopolymer was used as optical gain medium innovatively. By adopting high-viscosity aqueous protein ink and optimized scanning mode, protein-based WGM microlasers were customized with exquisite true 3D geometry and smooth morphology. Comparable to previously reported artificial polymers, protein-based WGM microlasers here were endowed with valuable performances including steady operation in air and even in aqueous environments, and a higher quality value (Q) of several thousands (without annealing). Due to the “smart” feature of protein hydrogel, lasing spectrum was responsively adjusted by step of ~0.4 nm blueshift per 0.83-mmol/L Na2SO4 concentration change (0 ~ 5-mmol/L in total leading to ~2.59-nm blueshift). Importantly, other performances including Q, FWHM, FSR, peak intensities, exhibited good stability during adjustments. So, these protein-based 3D WGM microlasers might have potential in applications like optical biosensing and tunable “smart” biolasers, useful in novel photonic biosystems and bioengineering.

Fabrication of three-dimensional proteinaceous micro- and nano-structures by femtosecond laser cross-linking

“…The concept of environmentally friendly optical devices 41,42 has also been demonstrated by the fabrication of a whispering-gallery-mode micro-laser 53 . Figure 6b shows the smoothness and fabrication accuracy of the disk structure that is necessary to control the gallery-mode.…”

“…This micro-laser performed well in air as well as in aqueous solutions. Furthermore, Sun et al demonstrated that the device was responsive to the ionic strength of the solution, thus suggesting applications in smart microfluidic devices 53 . Cell culture, in situ guidance and capture Cell culture offers possibly the widest range of applications for proteinaceous microstructures due to the variety of cell-cell interactions and microenvironmental niches of cells.…”

“…In addition to the pH-tunable microlenses introduced in the previous section, a flexible micro-sized kinoform phase lens (KPL) 41 and a responsive whispering-gallery-mode micro-laser 53 have been fabricated based on this concept. Figure 6a presents a KPL formed from polydimethylsiloxane (PDMS) as a flexible diffractive device with good surface properties and a suitable lifetime in an aqueous environment 41 .…”

High-Q silk fibroin whispering gallery microresonator

“…In fact, biodegradation and biocompatibility are two of the most important factors for in-vivo biosensing [12]. In this case, a WGM microresonator made from biomaterial possessing both biodegradation and biocompatibility will be an excellent candidate for in-vivo biosensing [13]. Silk fibroin originally from Bombyx mori (i.e., silkworm), has desired properties for biosensing applications, including non-toxicity, biodegradation, biocompatibility, and high transparency in visible light band (>95 %) [14][15][16][17][18][19][20], making it a suitable material alternative for WGM resonators.…”

Biomaterial microlasers implantable in the cornea, skin, and blood

“…Lasers made entirely from biomaterials were also demonstrated. For example, a distributed feedback laser (DFB) was made from riboflavin doped gelatin [12] and silk [13], and whispering-gallery-mode (WGM) lasing has been achieved in water droplets [14,15] and protein microspheres [16]. …”