This work reports a ZIF-8 (ZIF: Zeolitic Imidazolate Framework)-assisted NaYF4:Yb,Tm@ZnO upconverter for the photoelectrochemical (PEC) biosensing of carcinoembryonic antigen (CEA) under near-infrared (NIR) irradiation on a homemade 3D-printed device with DNA walker-based amplification strategy. The composite photosensitive material NaYF4:Yb,Tm@ZnO, as converter to transfer NIR import to photocurrent output, was driven from annealed NaYF4:Yb,Tm@ZIF-8. Yb3+ and Tm3+-codoped NaYF4 (NaYF4:Yb,Tm) converted NIR excitation into UV emission, matching with the absorption of ZnO for in situ excitation to generate the photocurrent. Upon target CEA introduction, the swing arm of DNA walker including the sequence of CEA aptamer carried out the sandwiched bioassembly with CEA capture aptamer on the G-rich anchorage DNA tracks-functionalized magnetic beads. Thereafter, DNA walker was triggered, and the swing arm DNA was captured by the G-rich anchorage DNA according to partly complementary pairing and Exonuclease III (Exo III) consumed anchorage DNA by a burnt-bridge mechanism to go into the next cycle. The released guanine (G) bases from DNA walker enhanced the photocurrent response on a miniature homemade 3D-printed device consisting of the detection cell, dark box, and light platform. Under optimal conditions, NaYF4:Yb,Tm@ZnO-based NIR light-driven PEC biosensor presented high sensitivity and selectivity for CEA sensing with a detection limit of 0.032 ng mL-1. Importantly, our strategy provides a new horizon for the development of NIR-based PEC biosensors in the aspect of developing MOF-derived photoelectric materials, flexible design of a 3D-printed device, and effective signal amplification mode.

ZIF-8-Assisted NaYF4:Yb,Tm@ZnO Converter with Exonuclease III-Powered DNA Walker for Near-Infrared Light Responsive Biosensor

Lanthanide-doped upconversion nanoparticles capable of converting near-infrared excitation into UV and visible emissions have attracted considerable research interests in recent years. Low-density near-infrared light needed for excitation of these nanoparticles is nondestructive and highly penetrating, offering significant technological advantages for biological and photonic applications such as remote neuron modulation, super-resolution imaging, and short-wavelength lasing. In this review, we describe several emerging classes of upconversion nanoparticles that have been developed to promote these technological applications by providing boosted emission intensities. We explain how heavy doping, thermal stimulating, and hybridizing can be harnessed to maximize absorption of excitation light and minimize quenching processes in these nanomaterials.

Emerging Frontiers of Upconversion Nanoparticles

Multimodal synergistic therapy based on photodynamic therapy (PDT), photothermal therapy (PTT), and chemodynamic therapy (CDT) has attracted increasing attention in cancer therapy. However, the scant therapeutic efficiency is always a barrier for further application. Herein, a smart tumor microenvironment (TME) responsive nanocatalysts are developed by adopting Fe-Mn layered double hydroxides (FeMn-LDH) as an effective photothermal nanocarrier to load mesoporous silica and chlorin e6 (Ce6)-covalently coated upconversion nanoparticles (UCSP) for multimodal imaging for directed therapy. Under acidic TME, FeMn-LDH degrades into Fe3+ and Mn2+ ions to initiate a Fenton-like reaction inducing CDT and enhancing magnetic resonance imaging. Additionally, Fe3+ can decompose H2 O2 to oxygen (O2 ), enhancing PDT guided by UCSP. As a representative noninvasive imaging probe, the upconversion luminescence will recover after decomposition of FeMn-LDH, and provide high-resolution upconversion luminescent imaging guidance for pinpointed PDT. Moreover, the photothermal properties of FeMn-LDH can further enhance CDT effects. The synergistic therapy and multifunctional imaging can realize the integration of diagnosis and treatment.

Intelligent Fe-Mn Layered Double Hydroxides Nanosheets Anchored with Upconversion Nanoparticles for Oxygen-Elevated Synergetic Therapy and Bioimaging.

Lanthanide-doped upconversion nanoparticles are undergoing extensive investigations in many fields, particularly in biophotonics and photophysics. In an attempt to boost upconversion emission intensities, Yb-based fluoride crystals have been recently identified as more efficient alternatives to classical NaYF4 crystals. Yb-Based fluoride crystals featuring a maximal occupancy of the host lattice by Yb3+ sensitizers facilitate the utilization of excitation light and promote energy transfer to upconverting activators, which contributes to a significant enhancement of upconversion luminescence. In this article, we present a survey of recent studies on chemical preparations of Yb-based fluoride nanoparticles with well-defined size and morphology. We show that these Yb-based upconversion nanoparticles are playing important roles in a few emerging applications such as optogenetics, biodetection and upconversion lasing.

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Recent advances in the synthesis and application of Yb-based fluoride upconversion nanoparticles

Lanthanide-doped nanoparticles have great potential for energy conversion applications, as their optical properties can be precisely controlled by varying the doping composition, concentration, and surface structures, as well as through plasmonic coupling In this Perspective we highlight recent advances in upconversion emission modulation enabled by coupling upconversion nanoparticles with well-defined plasmonic nanostructures We emphasize fundamental understanding of luminescence enhancement, monochromatic emission amplification, lifetime tuning, and polarization control at nanoscale The interplay between localized surface plasmons and absorbed photons at the plasmonic metal-lanthanide interface substantially enriches the interpretation of plasmon-coupled nonlinear photophysical processes These studies will enable novel functional nanomaterials or nanostructures to be designed for a multitude of technological applications, including biomedicine, lasing, optogenetics, super-resolution imaging, photovoltaics, and photocatalysis

Surface Plasmon-Photon Coupling in Lanthanide-Doped Nanoparticles.

Plasmon-Enhanced Blue Upconversion Luminescence by Indium Nanocrystals

The attractive features of lanthanide-doped upconversion luminescence (UCL), such as high photostability, nonphotobleaching or photoblinking, and large anti-Stokes shift, have shown great potentials in life science, information technology, and energy materials. Therefore, UCL modulation is highly demanded toward expected emission wavelength, lifetime, and relative intensity in order to satisfy stringent requirements raised from a wide variety of areas. Unfortunately, the majority of efforts have been devoted to either simple codoping of multiple activators or variation of hosts, while very little attention has been paid to the critical role that sensitizers have been playing. In fact, different sensitizers possess different excitation wavelengths and different energy transfer pathways (to different activators), which will lead to different UCL features. Thus, rational design of sensitizers shall provide extra opportunities for UCL tuning, particularly from the excitation side. In this review, we specifically focus on advances in sensitizers, including the current status, working mechanisms, design principles, as well as future challenges and endeavor directions.

Recent Development in Sensitizers for Lanthanide-Doped Upconversion Luminescence.

Physical Manipulation of Lanthanide-Activated Photoluminescence

Phosphorescent iridium(III) complexes as lifetime-based biological sensors for photoluminescence lifetime imaging microscopy

Nanoclusters (NCs) bridge the gap between atoms and nanomaterials in not only dimension but also physicochemical properties. Precise chemical and structural control, as well as clear understanding of formation mechanisms, have been important to fabricate NCs with high performance in optoelectronics, catalysis, nanoalloys, and energy conversion and harvesting. Herein, taking advantage of the close chemical properties of Ln3+ (Ln = Eu, Nd, Sm, Gd, etc.) and Gd3+–Eu3+ energy transfer ion-pair, we report a clickable LnF3 nanoparticle assembly strategy allowing reliable fabrication of diversely structured NCs, including single-component, dimeric, core-shelled/core-shell-shelled, and reversely core-shelled/core-shell-shelled, particularly with synergized optical functionalities. Moreover, the purposely-embedded dual luminescent probes offer great superiority for in situ and precise tracking of tiny structural variations and energy transfer pathways within complex nanoarchitectures. Precisely controlling the chemical composition and structure of nanoclusters is an ongoing challenge. Here, the authors report a clickable assembly strategy to construct widely varied lanthanide nanoclusters with synergized optical functionalities.

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Jie Zhou

Papers

Plasmon-Enhanced Blue Upconversion Luminescence by Indium Nanocrystals

Recent Development in Sensitizers for Lanthanide-Doped Upconversion Luminescence.

Physical Manipulation of Lanthanide-Activated Photoluminescence

Phosphorescent iridium(III) complexes as lifetime-based biological sensors for photoluminescence lifetime imaging microscopy

A luminescent view of the clickable assembly of LnF3 nanoclusters.