Stable Fluorescence of Eu3+ Complex Nanostructures Beneath a Protein Skin for Potential Biometric Recognition.

Yue Zhao,Christopher D Snow,Ziyu Yao,Dan Xiu,Laurence A Belfiore,Yao Wang,Jianguo Tang,Yanan Xu

doi:10.3390/nano11092462

Yue Zhao, Christopher D Snow + Show 6 more

Open Access

https://doi.org/10.3390/nano11092462

Copy DOI

Journal: Nanomaterials	Publication Date: Sep 21, 2021
Citations: 6	License type: CC BY 4.0

Affiliation: Qingdao University, Colorado State University

Abstract

We designed and realized highly fluorescent nanostructures composed of Eu3+ complexes under a protein coating. The nanostructured material, confirmed by photo-induced force microscopy (PiFM), includes a bottom fluorescent layer and an upper protein layer. The bottom fluorescent layer includes Eu3+ that is coordinated by 1,10-phenanthroline (Phen) and oleic acid (O). The complete complexes (OEu3+Phen) formed higher-order structures with diameter 40–150 nm. Distinctive nanoscale striations reminiscent of fingerprints were observed with a high-resolution transmission electron microscope (HRTEM). Stable fluorescence was increased by the addition of Eu3+ coordinated by Phen and 2-thenoyltrifluoroacetone (TTA), and confirmed by fluorescence spectroscopy. A satisfactory result was the observation of red Eu3+ complex emission through a protein coating layer with a fluorescence microscope. Lanthanide nanostructures of these types might ultimately prove useful for biometric applications in the context of human and non-human tissues. The significant innovations of this work include: (1) the structural set-up of the fluorescence image embedded under protein “skin”; and (2) dual confirmations of nanotopography and unique nanofingerprints under PiFM and under TEM, respectively.

Highlights

Published: 21 September 2021The technology to implant chips under the skin for recognition, for example, radio frequency identification [1,2], has provided the recognition requirement through the under skin method, but this implantable chip is hard and does not match flexible and elastic skin.it is urgent and significant to develop technologies for flexible and biocompatible chips with a clear identifiable signal, which would be the extension of biometric recognition, to identify signals under skin from human and non-human sources
Fingerprint-Like Nanostructures Characterized by TEM, high-resolution transmission electron microscope (HRTEM), and elemental mapping was utiEnergy-dispersive X-ray spectroscopy (EDS) Mapping
The aggregate structure structure changed from solid nanospheres to fingerprint-like nanostructures when the changed from solid nanospheres to fingerprint-like nanostructures when the concentration concentration of oleic acid increased from 0.02 mol L−1 to 0.05 mol L−1, keeping the other of oleic acid increased from 0.02 mol L−1 to 0.05 mol L−1, keeping the other experimental experimental conditions unchanged (Figure 1a–e)

Summary

Introduction

It is urgent and significant to develop technologies for flexible and biocompatible chips with a clear identifiable signal, which would be the extension of biometric recognition, to identify signals under skin from human and non-human sources (for example, pets and rare animals). To realize this purpose, the available materials will be most important. Fluorescent materials based on lanthanide (Ln3+ ) complexes [4,5,6,7] exhibit sharp emission peaks and high fluorescence intensity compared with traditional fluorescent organic molecules. The advantages of distinctive emission spectra and photostability of Ln3+

Methods

Results

Conclusion