Nanofibers Doped with Dendritic Fluorophores for Protein Detection

Abstract

We report a solid-state, nanofiber-based optical sensor for detecting proteins with an anionic fluorescent dendrimer (AFD). The AFD was encapsulated in cellulose acetate (CA) electrospun nanofibers, which were deacetylated to cellulose to generate secondary porous structures that are desirable for enhancing molecular interactions, and thus better signaling. The protein sensing properties of the fibers were characterized by monitoring the fluorescence response of cytochrome c (cyt c), hemoglobin (Hgb), and bovine serum albumin (BSA) as a function of concentration. Effective quenching was observed for the metalloproteins, cyt c and Hgb. The effect was primarily due to energy transfer of the imbedded fluorescent dendrimers to the protein, as both proteins contain heme portions. Electron transfer, caused through the electrostatic effects in the binding of the anionic dendrimer to the positive patches of globular proteins, could be responsible as well. BSA, on the other hand, triggered a "turn-on" response in fluorescence, suggesting the negatively charged BSA reduces the pi-pi stacking of the partially dispersed, negatively charged dendritic fluorophores through repulsion forces, which results in an increase in fluorescence. Stern-Volmer constants (K(sv)) of the electrospun fibers were found to be 3.4 x 10(5) and 1.7 x 10(6) M(-1) for cyt c and Hgb, respectively. The reusability of the nanofibers is excellent: the nanofibers demonstrated less than 15% change of fluorescence intensity signal in a 5-cycle test.

Electrospun Nanostructures for High Performance Chemiresistive and Optical Sensors

“…Either quenching or enhancement of the emission is found following the interaction with cytochrome c, hemoglobin, or bovine serum albumin. The observed behavior is explained by energy transfer, electron transfer, and repulsion forces between interacting compounds . The device is reusable, featuring a decrease of the overall fluorescence intensity by 15% over five sensing cycles.…”

Light‐Emitting Electrospun Nanofibers for Nanophotonics and Optoelectronics

“…Other examples of optical sensors include nanofibers made by polyfluorene‐derivatives blended with PMMA, which display a high sensitivity toward plasmid DNA,56b and nanofibers made by a diphenylacetylene polymer, sensitive to explosive nitroaromatic compounds 120, 121. Optical sensors based on fluorescent nanofibers have also been developed for protein detection 122, 123. Wang et al124 have recently demonstrated ultrasensitive detection of explosives vapors, explosives residues on handprint and buried explosives, by means of emission quenching in a sensing film composed of electrospun nanofibers.…”

Electrospun Nanofiber-Based Sensors

“…11.6a, b). Davis et al [119] reported a protein sensor by encapsulating the anionic fluorescent dendrimer in electrospun CA fibers, which were deacetylated to cellulose to generate secondary porous structure that is desirable for enhancing molecular interactions. The results revealed that the sensor could be used to detect cytochrome-c of 0.1 M with good reversibility (Fig.…”