Plasmon Modulated Upconversion Biosensors

Abstract

Over the past two decades, lanthanide-based upconversion nanoparticles (UCNPs) have been fascinating scientists due to their ability to offer unprecedented prospects to upconvert tissue-penetrating near-infrared light into color-tailorable optical illumination inside biological matter. In particular, luminescent behavior UCNPs have been widely utilized for background-free biorecognition and biosensing. Currently, a paramount challenge exists on how to maximize NIR light harvesting and upconversion efficiencies for achieving faster response and better sensitivity without damaging the biological tissue upon laser assisted photoactivation. In this review, we offer the reader an overview of the recent updates about exciting achievements and challenges in the development of plasmon-modulated upconversion nanoformulations for biosensing application.

Keywords: biosensing; fluorescence resonance energy transfer (FRET); gold nanoparticles (GNPs); plasmon modulated upconversion; plasmon-enhanced upconversion; plasmonic nanoparticles (PNPs); surface plasmon resonance (SPR); upconversion nanoparticles (UCNPs); upconversion quenching.

Figure 1

(A) Representative TEM image of NaYF₄:Yb,Tm UCNPs (scale 50 nm) with digital inset of their UC emission under NIR laser. (B) Upconversion process of Tm³⁺ activator under 980 nm and 808 nm excitation.

Figure 2

(A) Schematics of a metal nanoparticle’s electron cloud oscillation. (B) Spectral overlap between metal nanoparticle’s SPR and upconversion nanoparticles emission or excitation profile. Reprinted with permission from reference [53].

Figure 3

Sensing principle of the bifunctional UCNPs/AuNPs based nanoprobe for detection of (A) AchE and (B) Cd²⁺ ions with GSH regulation. Representative TEM images of (C) UCNPs, (D) AuNPs, (E) UCNPs/AuNPs, and (F) aggregation in UCNPs/AuNPs caused by post-addition of AChE and ATC. Reprinted with permission from reference [62].

Figure 4

(A) Schematics of the UCNPs–AuNPs plasmon-modulated biosensing platform for highly sensitive detection of tumor-related ncRNA via the Exo III-assisted cycling amplification strategy. Reprinted with permission from reference [75]. (B) Schematics of the composition and energy transfer mechanism of ssDNA optical sensor composed of PSA/SiO₂ coated UCNP and cyclometalated Ir(III)-AuNPs. Reprinted with permission from reference [73].

Figure 5

(A) Comparison illustration of homogenous and heterogeneous sensor for Ebola virus detection. Reprinted with permission from reference [80]. (B) Schematics of COVID S protein detection using plasmon modulated upconversion biosensing system. Reprinted with permission from reference [81].

Figure 6

(A) Illustration of the selective plasmon-enhanced green emission upconversion nanoprobe for temperature sensing, which include: schematics of the fabrication process, optical images of the sensor upon laser excitation and comparative illustration of the upconversion photoluminescence enhancement induced by Au nanofilm. Reprinted with permission from reference [83]. (B) Optical images of UCNPs and UCNPs/WO solutions under a 980 nm laser illumination. Fluorescence intensity ratio changes from the air to the mouth (black line), hand skin (red line) and time-dependent breath sensor response (dotted line). Reprinted with permission from reference [84].