Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons. This fundamentally interesting process has many ...applications in biomedical imaging, light source and display technology, and solar energy harvesting. In this review we discuss the underlying physical principles and their modelling using rate equations. We discuss how the understanding of photophysical processes enabled a strategic influence over the optical properties of upconversion especially in rationally designed materials. We subsequently present an overview of recent experimental strategies to control and optimize the optical properties of upconversion nanoparticles, focussing on their emission spectral properties and brightness.
Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons.
The emerging nanomedicine therapeutics have incorporated photonics technologies to develop precise medical treatment. Among the light regulated approaches, light-induced liposome technology has been ...explored and developed as a novel tool for spatiotemporal control of cargo release. Compared with the traditional liposome formulation, this triggering feature largely enhanced the therapeutic efficacy and minimized the side effects of the therapeutic substance. In this review paper, we discussed the basics of the light-induced liposomes including the engineering methods and photoresponsiveness mechanisms. We also reviewed current biomedical studies relating to light-induced liposome delivery systems, with an emphasis in the field of cancer therapy.
Light induced liposomes for gene/drug delivery applications. Display omitted
Detection of a very low amount of cytokines such as interleukin-6 (IL-6) in clinical fluids is important in biomedical research and clinical applications. Here, we demonstrate spatially-localized ...ultrasensitive (femtogram mL−1) level detection of IL-6 in serum and in cell culture media. Our approach is based on a sandwich immunosensor fabricated on the surface of an optical fibre. Firstly, the biotinylated IL-6 capture antibody was immobilized on the fibre surface by biotin-streptavidin coupling. Then the fabricated fibre was used for capturing IL-6 followed by exposure to detection antibody which was labeled with the fluorescent magnetic nanoparticles to report the signal. A linear relationship between IL-6 concentration and the fluorescence signal was obtained in the range from 0.4pgmL−1 to 400pgmL−1 of IL-6, with the limit of detection down to 0.1pgmL−1. In addition, this optical fibre sensor was successfully applied for the localized detection of IL-6 with the spatial resolution of 200µm and a sample volume of 1µL. Finally, the performance of the fibre sensor was demonstrated by detection of IL-6 secreted by BV-2 cells with comparable performance of the conventional enzyme-linked immunosorbent assay (ELISA).
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•The capture antibodies were modified on the fibre based immunosensing interface by biotin-streptavidin coupling.•The fibre sensor can detect spatially localized IL-6 in serum.•The detection limit of this assay can up to femtogram mL−1 level.
Liposomes have been well established as an effective drug delivery system, due to simplicity of their preparation and unique characteristics. However conventional liposomes are unsuitable for the ...on-demand content release, which limits their therapeutic utility. Here we report X-ray-triggerable liposomes incorporating gold nanoparticles and photosensitizer verteporfin. The 6 MeV X-ray radiation induces verteporfin to produce singlet oxygen, which destabilises the liposomal membrane and causes the release of cargos from the liposomal cavity. This triggering strategy is demonstrated by the efficiency of gene silencing in vitro and increased effectiveness of chemotherapy in vivo. Our work indicates the feasibility of a combinatorial treatment and possible synergistic effects in the course of standard radiotherapy combined with chemotherapy delivered via X-ray-triggered liposomes. Importantly, our X-ray-mediated liposome release strategy offers prospects for deep tissue photodynamic therapy, by removing its depth limitation.
Investigating the effect of particle morphology and size on sensitivity of UC thermometer and obtain nano-sized thermometry towards application in biology.
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•Rice-like, 2D hexagonal ...plate-like and truncated octahedral structures YF3: Er3+/Yb3+were prepared.•Morphology-dependent UC emission color, heating capabilities and thermometric sensitivity were investigated.•Stable thermometric sensitivity is independent of sizes and morphologies of YF3: Er3+/Yb3+ samples.•The potentiality of rice-like nano-crystals for non-contact temperature detection in sub-tissue was demonstrated by ex vivo experiments.
Er3+/Yb3+ co-doped YF3 samples with uniform rice-like, two-dimension (2D) hexagonal nano-architectures and truncated octahedral micro-crystals were synthesized through a one-step hydrothermal method, and their possible growth mechanisms were also proposed. Upon 980nm excitation, the up-conversion (UC) emitting color of samples was finely modulated from yellow to pure green with increasing the particle size, which was interpreted in terms of non-radiative process and surface effect. Thermometric capabilities of samples with different morphologies were evaluated based on the fluorescence intensity ratio (FIR) of 2H11/2 and 4S3/2 levels through temperature-dependent UC spectra, and the optimal absolute sensitivities of samples were all approached to about 0.0026K-1 at 490K. The potentiality of rice-like nano-crystals for temperature detection in sub-tissue was demonstrated by ex vivo experiments. Results display that the sensitivity of YF3: Er3+/Yb3+ nano/micro-crystals is independent of morphologies and sizes, which exploit an effective avenue for developing UC-based thermometers in sub-tissue with stable sensitivity.
•A CRISPR/Cas12a-based recipe for a broadly applicable ELISA sensitivity amplification.•Capable of integrated into commercial HRP-based ELISA kit without changing the original reagents or setup.•A ...possible solution to rapidly deliver a user-friendly and affordable sensitivity amplifier to end-users.•A hybrid single strand DNA oligo and antibody conjugate targeting the HRP enzyme.•2 orders of magnitude increase in sensitivity of a commercial HRP-based ELISA kit for IFN-γ detection.
The collateral cleavage function is only a corollary of programmable nuclease activity of certain Cas effectors, such as Cas12 and Cas13, but it can be utilised to amplify fluorescence signals in various CRISPR/Cas-based biosensing systems. In this work, this special signal amplification capability of CRISPR/Cas12a ribonucleoproteins has been employed to increase the sensitivity of a broad class of commercial ELISA systems with undisclosed chemistry except for the use of horseradish peroxidase (HRP), a common signal reporting molecule. We demonstrated that such ELISA systems with HRP on the detection antibody, can be amplified by 2 orders of magnitude using an example commercial IFN-γ ELISA kit where the detection limit was decreased from 312.5 pg/mL to 1.2 pg/mL. The detection range was simultaneously increased from 2 orders to 3 orders of magnitude. Our CRISPR/Cas12a-based ELISA Sensitivity Amplifier (CES-Amplifier) approach is based on a hybrid single strand DNA oligo and antibody conjugate targeting the HRP enzyme. The CES-Amplifier can be directly integrated into commercial ELISA kits to replace their original last step, without any additional changes of the ELISA kit reagents or setup. In this way, our CES-Amplifier provides a versatile and affordable approach for expanding CRISPR/Cas-based biosensing to a wide range of non-nucleic acid analytes.
Recent advances in CRISPR/Cas biosensing have led to impressive performance in sensitivity, specificity, and speed for nucleic acid detection. However, the remarkable advantages (such as ...universality, ultralow, attomolar detection limits) of CRISPR/Cas biosensing systems are limited in testing non-nucleic acid targets. Herein, by synthesizing a functional hybrid conjugate of antibody and single strand DNA oligonucleotide, we had successfully demonstrated the capability to integrate CRISPR/Cas12a-based signal amplification into different types of immunoassay schemes without the need for any additional recognition molecule or molecular synthesis during the detection process, thus providing a simple but generally applicable approach to improve the conventional immunoassays with attomolar sensitivity for small protein detections, referred as the CRISPR-based Universal Immunoassay Signal Enhancer (CRUISE). CRUISE is capable of being integrated into various immunoassays either through the primary antibody or the secondary antibody, with sensitivity down to 1 fg mL−1 (∼50 aM) and 6 logs of linear range for detecting cytokines, such as IFN-γ and EGFR, under 3–4 h. It has a 103 times higher sensitivity compared to a commercial IFN-γ ELISA kit, but uses the same experimental scheme. The same 1 fg mL−1 sensitivity along with 6 logs of linear range was realized for IFN-γ detection in human plasma samples. We are expecting that our CRUISE provides an alternative but simple, user-friendly and effective strategy for those who rely on the use of immunoassays, while struggling with the limits of their sensitivity or detection ranges.
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•A universal and user-friendly approach to integrate CRISPR/Cas12a trans-cleavage into mainstream immunoassay schemes.•No need for additional target recognition molecules except antibody.•Same experimental protocols and setup as conventional immunoassays.•Breaks through the sensitivity barrier of conventional sandwich immunoassay, such as ELISA.•Capable of reaching aM-level sensitivity for small protein diagnostics but with shorter time.
Investigation of the unclear influential factors to thermal sensing capability is the only way to achieve highly sensitive thermometry, which is greatly needed to meet the growing demand for ...potential sensing applications. Here, the effect from the phonon energy of a matrix on the sensitivity of upconversion (UC) microthermometers is elaborately discussed using a controllable method. Uniform truncated octahedral YF3:Er3+/Yb3+ microcrystals were prepared by a hydrothermal approach, and phase transformation from YF3 to YOF and Y2O3 with nearly unchanged morphology and size was successfully realized by controlling the annealing temperature. The phonon energies of blank matrixes were determined by FT-IR spectra and Raman scattering. Upon 980 nm excitation, phonon energy-dependent UC emitting color was finely tuned from green to yellow for three samples, and the mechanisms were proposed. Thermal sensing behaviors based on the TCLs (2H11/2/4S3/2) were evaluated, and the sensitivities gradually grew with the increase in the matrix’s phonon energy. According to chemical bond theory and first-principle calculations, the most intrinsic factors associated with thermometric ability were qualitatively demonstrated through analyzing the inner relation between the phonon energy and bond covalency. The exciting results provide guiding insights into employing appropriate host materials with desired thermometric ability while offering the possibility of highly accurate measurement of temperature.
A stable label-free amperometric immunosensor is presented based on gold nanoparticles and graphene oxide nanocomposites for detection of cardiac troponin-I in the early diagnosis of myocardial ...infarction. For designing of the sensing platform, firstly the nanocomposites based on GO and AuNPs were prepared and anchored on electrode surfaces. The formed nanocomposites provided a platform with big surface area for loading anti-cTnI capture antibody, and worked as a bridge for fast electron transfer subsequently increased the sensitivity. Moreover, the linkages between AuNP, GO, and electrodes were based on covalent bonding by aryldiazonium salt coupling chemistry, which favors the stability of the sensing interface. Finally, the anti-cTnI detection antibody was immobilized on GO tailored with ferrocene molecules, functioning as the signal reporter for the detection of cTnI. The modification process was monitored using electrochemistry, SEM, XPS. The herein immunosensor demonstrates a good selectivity and high sensitivity against human-cTnI, and is capable of detecting cTnI at concentrations as low as 0.05 ng mL−1, which is 100 times lower than that possible by conventional methods. It is potential to design the portable sensing platform based on AuNPs and GO nanocomposites for future point-of-care diagnostics.
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•Nanocomposites based on GO and AuNPs were prepared and anchored on the electrode surfaces covalently to form a stable sensing interface.•The anti-cTnI detection antibody was immobilized on GO tailored with ferrocene molecules, functioning as the signal reporter for the detection of cTnI.•The detectable concentration of cTnI is 0.05 ng mL-1 in buffer with the assay time of less than 5 min.•The herein simple and novel approach for fabrication of AuNP and graphene based platform is promising for future fabrication of point-of-care devices.
The ultimate frontier in nanomaterials engineering is to realize their composition control with atomic scale precision to enable fabrication of nanoparticles with desirable size, shape and surface ...properties. Such control becomes even more useful when growing hybrid nanocrystals designed to integrate multiple functionalities. Here we report achieving such degree of control in a family of rare-earth-doped nanomaterials. We experimentally verify the co-existence and different roles of oleate anions (OA(-)) and molecules (OAH) in the crystal formation. We identify that the control over the ratio of OA(-) to OAH can be used to directionally inhibit, promote or etch the crystallographic facets of the nanoparticles. This control enables selective grafting of shells with complex morphologies grown over nanocrystal cores, thus allowing the fabrication of a diverse library of monodisperse sub-50 nm nanoparticles. With such programmable additive and subtractive engineering a variety of three-dimensional shapes can be implemented using a bottom-up scalable approach.
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