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10 pages, 2884 KiB

Open AccessArticle

Staging of Skin Cancer Based on Hyperspectral Microscopic Imaging and Machine Learning

by Lixin Liu, Meijie Qi, Yanru Li, Yujie Liu, Xing Liu, Zhoufeng Zhang and Junle Qu

Biosensors 2022, 12(10), 790; https://doi.org/10.3390/bios12100790 - 25 Sep 2022

Cited by 10 | Viewed by 2199

Skin cancer, a common type of cancer, is generally divided into basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma (MM). The incidence of skin cancer has continued to increase worldwide in recent years. Early detection can greatly reduce its morbidity [...] Read more.

Skin cancer, a common type of cancer, is generally divided into basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma (MM). The incidence of skin cancer has continued to increase worldwide in recent years. Early detection can greatly reduce its morbidity and mortality. Hyperspectral microscopic imaging (HMI) technology can be used as a powerful tool for skin cancer diagnosis by reflecting the changes in the physical structure and microenvironment of the sample through the differences in the HMI data cube. Based on spectral data, this work studied the staging identification of SCC and the influence of the selected region of interest (ROI) on the staging results. In the SCC staging identification process, the optimal result corresponded to the standard normal variate transformation (SNV) for spectra preprocessing, the partial least squares (PLS) for dimensionality reduction, the hold-out method for dataset partition and the random forest (RF) model for staging identification, with the highest staging accuracy of 0.952 ± 0.014, and a kappa value of 0.928 ± 0.022. By comparing the staging results based on spectral characteristics from the nuclear compartments and peripheral regions, the spectral data of the nuclear compartments were found to contribute more to the accurate staging of SCC. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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11 pages, 6450 KiB

Open AccessArticle

A Simple Optical Aerosol Sensing Method of Sauter Mean Diameter for Particulate Matter Monitoring

by Liangbo Li, Ang Chen, Tian Deng, Jin Zeng, Feifan Xu, Shu Yan, Shu Wang, Wenqing Cheng, Ming Zhu and Wenbo Xu

Biosensors 2022, 12(7), 436; https://doi.org/10.3390/bios12070436 - 21 Jun 2022

Cited by 4 | Viewed by 1644

Abstract

Mass concentration is a commonly used but insufficient metric to evaluate the particulate matter (PM) exposure hazard. Recent studies have declared that small particles have more serious impacts on human health than big particles given the same mass concentration. However, state-of-the-art PM sensors [...] Read more.

Mass concentration is a commonly used but insufficient metric to evaluate the particulate matter (PM) exposure hazard. Recent studies have declared that small particles have more serious impacts on human health than big particles given the same mass concentration. However, state-of-the-art PM sensors cannot provide explicit information of the particle size for further analysis. In this work, we adopt Sauter mean diameter (SMD) as a key metric to reflect the particle size besides the mass concentration. To measure SMD, an effective optical sensing method and a proof-of-concept prototype sensor are proposed by using dual wavelengths technology. In the proposed method, a non-linear conversion model is developed to improve the SMD measurement accuracy for aerosol samples of different particle size distributions and reflective indices based on multiple scattering channels. In the experiment of Di-Ethyl-Hexyl-Sebacate (DEHS) aerosols, the outputs of our prototype sensor demonstrated a good agreement with existing laboratory reference instruments with maximum SMD measurement error down to 7.04%. Furthermore, the simplicity, feasibility and low-cost features of this new method present great potential for distributed PM monitoring, to support sophisticated human exposure hazard assessment. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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11 pages, 2342 KiB

Open AccessArticle

Fiber-Enhanced Stimulated Raman Scattering and Sensitive Detection of Dilute Solutions

by Li Guo, Jing Huang, Yaxin Chen, Bohan Zhang and Minbiao Ji

Biosensors 2022, 12(4), 243; https://doi.org/10.3390/bios12040243 - 14 Apr 2022

Cited by 2 | Viewed by 2686

Abstract

Stimulated Raman scattering (SRS) is known to gain coherent amplification of molecular vibrations that allow for rapid and label-free chemical imaging in the microscopy setting. However, the tightly focused laser spot has limited the detection sensitivity, partly due to the tiny interaction volume. [...] Read more.

Stimulated Raman scattering (SRS) is known to gain coherent amplification of molecular vibrations that allow for rapid and label-free chemical imaging in the microscopy setting. However, the tightly focused laser spot has limited the detection sensitivity, partly due to the tiny interaction volume. Here, we report the use of metal-lined hollow-core fiber (MLHCF) to improve the sensitivity of SRS in sensing dilute solutions by extending the light–matter interaction volume through the fiber waveguide. With a focusing lens (100 mm FL) and 320 μm diameter fiber, we demonstrated an optimum enhancement factor of ~20 at a fiber length of 8.3 cm. More importantly, the MLHCF exhibited a significantly suppressed cross-phase modulation (XPM) background, enabling the detection of ~0.7 mM DMSO in water. Furthermore, the relationship between fiber length and SRS signal could be well explained theoretically. The fiber-enhanced SRS (FE-SRS) method may be further optimized and bears potential in the sensitive detection of molecules in the solution and gas phases. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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20 pages, 3652 KiB

Open AccessArticle

A Hybrid Titanium-Softmaterial, High-Strength, Transparent Cranial Window for Transcranial Injection and Neuroimaging

by Nana Yang, Fengyu Liu, Xinyue Zhang, Chenni Chen, Zhiyuan Xia, Su Fu, Jiaxin Wang, Jingjing Xu, Shuang Cui, Yong Zhang, Ming Yi, You Wan, Qing Li and Shengyong Xu

Biosensors 2022, 12(2), 129; https://doi.org/10.3390/bios12020129 - 18 Feb 2022

Cited by 5 | Viewed by 2952

Abstract

A transparent and penetrable cranial window is essential for neuroimaging, transcranial injection and comprehensive understanding of cortical functions. For these applications, cranial windows made from glass coverslip, polydimethylsiloxane (PDMS), polymethylmethacrylate, crystal and silicone hydrogel have offered remarkable convenience. However, there is a lack [...] Read more.

A transparent and penetrable cranial window is essential for neuroimaging, transcranial injection and comprehensive understanding of cortical functions. For these applications, cranial windows made from glass coverslip, polydimethylsiloxane (PDMS), polymethylmethacrylate, crystal and silicone hydrogel have offered remarkable convenience. However, there is a lack of high-strength, high-transparency, penetrable cranial window with clinical application potential. We engineer high-strength hybrid Titanium-PDMS (Ti-PDMS) cranial windows, which allow large transparent area for in vivo two-photon imaging, and provide a soft window for transcranial injection. Laser scanning and 3D printing techniques are used to match the hybrid cranial window to different skull morphology. A multi-cycle degassing pouring process ensures a good combination of PDMS and Ti frame. Ti-PDMS cranial windows have a high fracture strength matching human skull bone, excellent light transmittance up to 94.4%, and refractive index close to biological tissue. Ti-PDMS cranial windows show excellent bio-compatibility during 21-week implantation in mice. Dye injection shows that the PDMS window has a “self-sealing” to keep liquid from leaking out. Two-photon imaging for brain tissues could be achieved up to 450 µm in z-depth. As a novel brain-computer-interface, this Ti-PDMS device offers an alternative choice for in vivo drug delivery, optical experiments, ultrasonic treatment and electrophysiology recording. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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12 pages, 4452 KiB

Open AccessArticle

Hot-Band-Absorption-Induced Anti-Stokes Fluorescence of Aggregation-Induced Emission Dots and the Influence on the Nonlinear Optical Effect

by Yuhuang Zhang, Jing Zhou, Shiyi Peng, Wenbin Yu, Xiaoxiao Fan, Wen Liu, Zikang Ye, Ji Qi, Zhe Feng and Jun Qian

Biosensors 2021, 11(11), 468; https://doi.org/10.3390/bios11110468 - 22 Nov 2021

Cited by 4 | Viewed by 2422

Abstract

Hot-band absorption (HBA)-induced anti-Stokes fluorescence (ASF) with longer-wavelength excitation is one effective pathway to deep penetration and low autofluorescence in intravital fluorescence imaging, raising demands for fluorophores with broad spectra, high absorption, and strong emission. However, typical fluorescent dyes display some emission quenching [...] Read more.

Hot-band absorption (HBA)-induced anti-Stokes fluorescence (ASF) with longer-wavelength excitation is one effective pathway to deep penetration and low autofluorescence in intravital fluorescence imaging, raising demands for fluorophores with broad spectra, high absorption, and strong emission. However, typical fluorescent dyes display some emission quenching when their concentration is increased in order to obtain brighter fluorescence. In this work, the HBA-induced ASF of aggregation-induced emission (AIE) dots is reported. BPN-BBTD dots were synthesized and confirmed with a fluorescence enhancement and a considerable ASF intensity. In addition, the mechanism of ASF and the HBA process of BPN-BBTD dots were carefully validated and discussed. To obtain the full advantages of the long-wavelength excitation and the short fluorescence lifetime in deep-tissue bioimaging, a large-depth ASF confocal microscopic imaging of in vivo cerebral vasculature was conducted under the excitation of a 980 nm continuous wave laser after intravenous injection of BPN-BBTD dots. Meanwhile, the 3D structure of the cerebrovascular network was successfully reconstructed. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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8 pages, 1942 KiB

Open AccessCommunication

Distinguishing Amyloid β-Protein in a Mouse Model of Alzheimer’s Disease by Label-Free Vibrational Imaging

by Shaowei Li, Ziyi Luo, Renlong Zhang, Hao Xu, Ting Zhou, Liwei Liu and Junle Qu

Biosensors 2021, 11(10), 365; https://doi.org/10.3390/bios11100365 - 30 Sep 2021

Cited by 5 | Viewed by 2189

Abstract

Due to the increase in the average age of humans, Alzheimer’s disease (AD) has become one of the disorders with the highest incidence worldwide. Abnormal amyloid β protein (Aβ) accumulation is believed to be the most common cause of AD. Therefore, distinguishing the [...] Read more.

Due to the increase in the average age of humans, Alzheimer’s disease (AD) has become one of the disorders with the highest incidence worldwide. Abnormal amyloid β protein (Aβ) accumulation is believed to be the most common cause of AD. Therefore, distinguishing the lesion areas can provide clues for AD diagnosis. Here, we present an optical spectroscopy and imaging approach based on coherent anti-Stokes Raman scattering (CARS). Label-free vibrational imaging of Aβ in a mouse model of AD was performed to distinguish the lesion areas by studying the spectra of regions with and without Aβ plaques. Raman spectra in Aβ and non-Aβ regions exhibited a specific difference in the intensity ratio of the wave peaks detected at 2850 and 2930 cm⁻¹. In the non-Aβ region, the ratio of the peak intensity at 2850 cm⁻¹ to that at 2930 cm⁻¹ was approximately 1, whereas that in the Aβ region was 0.8. This label-free vibrational imaging may provide a new method for the clinical diagnosis and basic research of AD. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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12 pages, 24077 KiB

Open AccessArticle

The Spectroscopic Properties and Microscopic Imaging of Thulium-Doped Upconversion Nanoparticles Excited at Different NIR-II Light

by Tingting Peng, Rui Pu, Baoju Wang, Zhimin Zhu, Kai Liu, Fan Wang, Wei Wei, Haichun Liu and Qiuqiang Zhan

Biosensors 2021, 11(5), 148; https://doi.org/10.3390/bios11050148 - 10 May 2021

Cited by 3 | Viewed by 3126

Abstract

Lanthanide-doped upconversion nanoparticles (UCNPs) are promising bioimaging nanoprobes due to their excellent photostability. As one of the most commonly used lanthanide activators, Tm³⁺ ions have perfect ladder-type electron configuration and can be directly excited by bio-friendly near-infrared-II (NIR-II) wavelengths. Here, the emission [...] Read more.

Lanthanide-doped upconversion nanoparticles (UCNPs) are promising bioimaging nanoprobes due to their excellent photostability. As one of the most commonly used lanthanide activators, Tm³⁺ ions have perfect ladder-type electron configuration and can be directly excited by bio-friendly near-infrared-II (NIR-II) wavelengths. Here, the emission characteristics of Tm³⁺-doped nanoparticles under laser excitations of different near-infrared-II wavelengths were systematically investigated. The 1064 nm, 1150 nm, and 1208 nm lasers are proposed to be three excitation strategies with different response spectra of Tm³⁺ ions. In particular, we found that 1150 nm laser excitation enables intense three-photon 475 nm emission, which is nearly 100 times stronger than that excited by 1064 nm excitation. We further optimized the luminescence brightness after investigating the luminescence quenching mechanism of bare NaYF₄: Tm (1.75%) core. After growing an inert shell, a ten-fold increase of emission intensity was achieved. Combining the advantages of NIR-II wavelength and the higher-order nonlinear excitation, a promising facile excitation strategy was developed for the application of thulium-doped upconversion nanoparticles in nanoparticles imaging and cancer cell microscopic imaging. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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Review

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19 pages, 1797 KiB

Open AccessReview

Optical Imaging of Beta-Amyloid Plaques in Alzheimer’s Disease

by Ziyi Luo, Hao Xu, Liwei Liu, Tymish Y. Ohulchanskyy and Junle Qu

Biosensors 2021, 11(8), 255; https://doi.org/10.3390/bios11080255 - 29 Jul 2021

Cited by 11 | Viewed by 4317

Abstract

Alzheimer’s disease (AD) is a multifactorial, irreversible, and incurable neurodegenerative disease. The main pathological feature of AD is the deposition of misfolded β-amyloid protein (Aβ) plaques in the brain. The abnormal accumulation of Aβ plaques leads to the loss of some neuron functions, [...] Read more.

Alzheimer’s disease (AD) is a multifactorial, irreversible, and incurable neurodegenerative disease. The main pathological feature of AD is the deposition of misfolded β-amyloid protein (Aβ) plaques in the brain. The abnormal accumulation of Aβ plaques leads to the loss of some neuron functions, further causing the neuron entanglement and the corresponding functional damage, which has a great impact on memory and cognitive functions. Hence, studying the accumulation mechanism of Aβ in the brain and its effect on other tissues is of great significance for the early diagnosis of AD. The current clinical studies of Aβ accumulation mainly rely on medical imaging techniques, which have some deficiencies in sensitivity and specificity. Optical imaging has recently become a research hotspot in the medical field and clinical applications, manifesting noninvasiveness, high sensitivity, absence of ionizing radiation, high contrast, and spatial resolution. Moreover, it is now emerging as a promising tool for the diagnosis and study of Aβ buildup. This review focuses on the application of the optical imaging technique for the determination of Aβ plaques in AD research. In addition, recent advances and key operational applications are discussed. Full article

(This article belongs to the Special Issue Optical Sensors for Bio-Sensing, Imaging and Theranostics Applications)

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