Gold nanoclusters performing as contrast agents for non-invasive imaging of tissue-like phantoms via two-photon excited fluorescence lifetime imaging

The Analyst ◽  
2021 ◽  
Author(s):  
Alexandru-Milentie Hada ◽  
Ana-Maria Craciun ◽  
Simion Astilean
Keyword(s):  
Contrast Agents ◽  
Fluorescence Lifetime ◽  
Gold Nanoclusters ◽  
Fluorescence Lifetime Imaging ◽  
Scientific Interest ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Non Invasive ◽  
Wide Range

Recently, gold nanoclusters (AuNCs) have received considerable scientific interest due to their ability to generate intrinsic photoluminescence, making them suitable for a wide range of applications, such as sensing, biolabeling...

scholarly journals Intrinsic Photoluminescence of Solid-State Gold Nanoclusters: Towards Fluorescence Lifetime Imaging of Tissue-Like Phantoms Under Two-Photon Near-Infrared Excitation

2021 ◽  
Author(s):  
Hada Alexandru-Milentie ◽  
Ana-Maria Craciun ◽  
Simion Astilean
Keyword(s):  
Solid State ◽  
Fluorescence Lifetime ◽  
Gold Nanoclusters ◽  
Homogeneous Distribution ◽  
Cancer Tissue ◽  
Fluorescence Lifetime Imaging ◽  
Photoluminescence Properties ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Non Invasive

Abstract Gold nanoclusters (AuNCs) have attracted extensive attention as light-emissive materials with unique advantages such as high photostability, large Stoke shifts and low toxicity. However, a better understanding of their solid-state photoluminescence properties is still needed. Herein, we investigated for the first time the intrinsic photoluminescence properties of lyophilized bovine serum albumin stabilized AuNCs (BSA-AuNCs) via fluorescence lifetime imaging microscopy (FLIM) studies performed under both one and two photon excitations (OPE and TPE) on individual microflakes, combined with fluorescence spectroscopic investigations. Both in solution and solid-state, the synthesized BSA-AuNCs exhibit photoluminescence in the first biological window with an absolute quantum yield of 6% and high photostability under continuous irradiation. Moreover, under both OPE and TPE conditions, solid BSA-AuNCs samples exhibited a low degree of photobleaching, while FLIM assays prove the homogeneous distribution of the photoluminescence signal inside the microflakes. Finally, we demonstrate the ability of BSA-AuNCs to perform as reliable bright and photostable contrast agents for the visualization of cancer tissue mimicking agarose-phantoms using FLIM approach under non-invasive TPE. Therefore, our results emphasize the great potential of the as synthesized BSA-AuNCs for ex vivo and in vivo non-invasive NIR imaging applications.

scholarly journals Intrinsic Photoluminescence of Solid-State Gold Nanoclusters: Towards Fluorescence Lifetime Imaging of Tissue-Like Phantoms Under Two-Photon Near-Infrared Excitation

2021 ◽  
Vol 9 ◽  
Author(s):  
Alexandru-Milentie Hada ◽  
Ana-Maria Craciun ◽  
Simion Astilean
Keyword(s):  
Solid State ◽  
Fluorescence Lifetime ◽  
Gold Nanoclusters ◽  
Homogeneous Distribution ◽  
Cancer Tissue ◽  
Fluorescence Lifetime Imaging ◽  
Photoluminescence Properties ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Non Invasive

Gold nanoclusters (AuNCs) have attracted extensive attention as light-emissive materials with unique advantages such as high photostability, large Stoke shifts and low toxicity. However, a better understanding of their solid-state photoluminescence properties is still needed. Herein, we investigated for the first time the intrinsic photoluminescence properties of lyophilized bovine serum albumin stabilized AuNCs (BSA-AuNCs) via fluorescence lifetime imaging microscopy (FLIM) studies performed under both one and two photon excitations (OPE and TPE) on individual microflakes, combined with fluorescence spectroscopic investigations. Both in solution and solid-state, the synthesized BSA-AuNCs exhibit photoluminescence in the first biological window with an absolute quantum yield of 6% and high photostability under continuous irradiation. Moreover, under both OPE and TPE conditions, solid BSA-AuNCs samples exhibited a low degree of photobleaching, while FLIM assays prove the homogeneous distribution of the photoluminescence signal inside the microflakes. Finally, we demonstrate the ability of BSA-AuNCs to perform as reliable bright and photostable contrast agents for the visualization of cancer tissue mimicking agarose-phantoms using FLIM approach under non-invasive TPE. Therefore, our results emphasize the great potential of the as synthesized BSA-AuNCs for ex vivo and in vivo non-invasive NIR imaging applications.

scholarly journals Optical Estimation of Absolute Membrane Potential Using One- and Two-Photon Fluorescence Lifetime Imaging Microscopy

2021 ◽  
Author(s):  
Julia R. Lazzari-Dean ◽  
Evan W. Miller
Keyword(s):  
Membrane Potential ◽  
Fluorescence Lifetime ◽  
Single Photon ◽  
Photon Counting ◽  
Fluorescence Lifetime Imaging ◽  
Single Photon Counting ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Wide Range ◽  
Relative Measurements

AbstractBackgroundMembrane potential (Vmem) exerts physiological influence across a wide range of time and space scales. To study Vmem in these diverse contexts, it is essential to accurately record absolute values of Vmem, rather than solely relative measurements.Materials & MethodsWe use fluorescence lifetime imaging of a small molecule voltage sensitive dye (VF2.1.Cl) to estimate mV values of absolute membrane potential.ResultsWe test the consistency of VF2.1.Cl lifetime measurements performed on different single photon counting instruments and find that they are in striking agreement (differences of <0.5 ps/mV in the slope and <50 ps in the y-intercept). We also demonstrate that VF2.1.Cl lifetime reports absolute Vmem under two-photon (2P) illumination with better than 20 mV of Vmem resolution, a nearly 10-fold improvement over other lifetime-based methods.ConclusionsWe demonstrate that VF-FLIM is a robust and portable metric for Vmem across imaging platforms and under both one-photon and two-photon illumination. This work is a critical foundation for application of VF-FLIM to record absolute membrane potential signals in thick tissue.

scholarly journals In vivo non-invasive staining-free visualization of dermal mast cells in healthy, allergy and mastocytosis humans using two-photon fluorescence lifetime imaging

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marius Kröger ◽  
Jörg Scheffel ◽  
Viktor V. Nikolaev ◽  
Evgeny A. Shirshin ◽  
Frank Siebenhaar ◽  
...  
Keyword(s):  
Mast Cells ◽  
Fluorescence Lifetime ◽  
The Body ◽  
Papillary Dermis ◽  
Fluorescence Lifetime Imaging ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Non Invasive ◽  
Activation Status

Abstract Mast cells (MCs) are multifunctional cells of the immune system and are found in skin and all major tissues of the body. They contribute to the pathology of several diseases including urticaria, psoriasis, atopic dermatitis and mastocytosis where they are increased at lesional sites. Histomorphometric analysis of skin biopsies serves as a routine method for the assessment of MC numbers and their activation status, which comes with major limitations. As of now, non-invasive techniques to study MCs in vivo are not available. Here, we describe a label-free imaging technique to visualize MCs and their activation status in the human papillary dermis in vivo. This technique uses two-photon excited fluorescence lifetime imaging (TPE-FLIM) signatures, which are different for MCs and other dermal components. TPE-FLIM allows for the visualization and quantification of dermal MCs in healthy subjects and patients with skin diseases. Moreover, TPE-FLIM can differentiate between two MC populations in the papillary dermis in vivo—resting and activated MCs with a sensitivity of 0.81 and 0.87 and a specificity of 0.85 and 0.84, respectively. Results obtained on healthy volunteers and allergy and mastocytosis patients indicate the existence of other MC subpopulations within known resting and activated MC populations. The developed method may become an important tool for non-invasive in vivo diagnostics and therapy control in dermatology and immunology, which will help to better understand pathomechanisms involving MC accumulation, activation and degranulation and to characterize the effects of therapies that target MCs.

Non-invasive imaging of skin cancer with fluorescence lifetime imaging using two photon tomography

2011 ◽  
Author(s):  
Rakesh Patalay ◽  
Clifford Talbot ◽  
Yuriy Alexandrov ◽  
Ian Munro ◽  
Hans Georg Breunig ◽  
...  
Keyword(s):  
Skin Cancer ◽  
Fluorescence Lifetime ◽  
Fluorescence Lifetime Imaging ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Non Invasive

scholarly journals Sperm metabolism is altered during storage by female insects: evidence from two-photon autofluorescence lifetime measurements in bedbugs

2015 ◽  
Vol 12 (110) ◽  
pp. 20150609 ◽  
Author(s):  
Klaus Reinhardt ◽  
Hans Georg Breunig ◽  
Aisada Uchugonova ◽  
Karsten König
Keyword(s):  
Fluorescence Lifetime ◽  
Sperm Cells ◽  
Fluorescence Lifetime Imaging ◽  
Two Photon ◽  
Lifetime Imaging ◽  
Photon Excitation ◽  
The Common ◽  
The Mean ◽  
The Difference ◽  
Male Genotype

We explore the possibility of characterizing sperm cells without the need to stain them using spectral and fluorescence lifetime analyses after multi-photon excitation in an insect model. The autofluorescence emission spectrum of sperm of the common bedbug, Cimex lectularius , was consistent with the presence of flavins and NAD(P)H. The mean fluorescence lifetimes showed smaller variation in sperm extracted from the male (tau m, τ m = 1.54–1.84 ns) than in that extracted from the female sperm storage organ (tau m, τ m = 1.26–2.00 ns). The fluorescence lifetime histograms revealed four peaks. These peaks (0.18, 0.92, 2.50 and 3.80 ns) suggest the presence of NAD(P)H and flavins and show that sperm metabolism can be characterized using fluorescence lifetime imaging. The difference in fluorescence lifetime variation between the sexes is consistent with the notion that female animals alter the metabolism of sperm cells during storage. It is not consistent, however, with the idea that sperm metabolism represents a sexually selected character that provides females with information about the male genotype.

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