We demonstrate the first in-fiber light-induced bioactive biotin-functionalization via photobleaching fluorophore-conjugated biotin. Photobleaching the fluorophores generated free radicals that bind to the albumin-passivated inner surface of pure silica photonic crystal fiber. The subsequent attachment of dye-conjugated streptavidin to the bound biotin qualified the photo-immobilization process and demonstrated a potential for the construction of in-fiber macromolecular assemblies or multiplexes. Compared with other in-fiber bioactive coating methods, the proposed light-induced technique requires only a low-power light source, without the need for additional preactivation steps or toxic chemical reagents. This method, hence, enables a simple and compact implementation for potential biomedical applications.
Multi-layered liposomes, comprising a concentric series of lipid bilayers – separated at fixed distances and compartmentalizing aqueous solutions of alternating refractive indices – are proposed as optical Bragg resonators.
Seminal work focuses on the feasibility of successive encapsulations coupled with size-control via extrusion. Synthesis
criteria for realization of these liposomes were subsequently discussed based on experimental observations. Numerical
studies of the proposed structure showed discernible band gaps, qualifying their potential application in biological lasing.
A lab-in-fiber platform, comprising a photonic crystal fiber component for light-sample interaction, was experimentally demonstrated to be effective as a sensor and micro-reactor. Specifically, it enabled the discrimination between free and liposome-encapsulated fluorophores as well as allowed for the excitation of in-fiber plasmonic photothermal effects, by alternating between different fiber-coupled inputs. The significant increase in fluorescence emissions upon release of fluorophores, encapsulated within liposomes at self-quenching concentrations, was perceived as a shoulder in the device’s spectral output that otherwise only comprises the input excitation. Markedly, the observed shoulder was only discernible when the photonic crystal fiber was placed in a bent orientation. This was explained to be associated with the bending-induced refractive index profile changes in the fiber cross section that led to increased amounts of evanescent fields for light-sample interactions. Results highlighted the viability of the lab-in-fiber platform as an alternative to current lab-on-a-chip devices.
Photonic crystal fibers (PCFs), although a highly effective platform for sensing, encounter difficulties with coupling as
well as infiltration and evacuation. A PCF integrated microfluidic chip has therefore been fabricated to demonstrate
improved coupling for real-time chemical sensing. Furthermore, an extremely sensitive dip-shifting analysis was
employed for the detection regime. Results eventually demonstrated its notable sensitivity and a refractive index
resolution of 10-7 RIU, rendering it suitable for utilization in highly sensitive sensing applications.