Wen Lo

Wen Lo
National Taiwan University | NTU · Department of Physics

About

89
Publications
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1,668
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Publications

Publications (89)
Article
Full-text available
Acetaminophen (APAP) overdose is one of the world’s leading causes of drug‐induced hepatotoxicity. Although traditional methods such as histological imaging and biochemical assays have been successfully applied to evaluate the extent of APAP‐induced liver damage, detailed effect of how APAP overdose affect the recovery of hepatobiliary metabolism r...
Article
In this work, we used multiphoton microscopic system for characterizing three-dimensional microstructure of collagen/chitosan polymeric scaffolds in a noninvasive fashion. Nonlinear optical signals including multiphoton autofluorescence (MAF) and second harmonic generation (SHG) derived from collagen/chitosan scaffolds were collected and analyzed....
Article
Purpose: To evaluate the efficacy of using forward second harmonic generation (SHG) and 2-dimensional fast Fourier-transform (2D-FFT) analysis for the label-free characterization and quantification of morphologic changes in the corneal stroma after collagen crosslinking (CXL). Setting: Department of Physics, National Taiwan University, Taipei, T...
Article
The intestinal mucosa exhibits high turnover rates with a balance of shedding and the migration of epithelial cells to maintain gut barrier function. Systemic diseases such as sepsis and major thermal injury accelerate the rate of cell shedding, subsequent gap formation, and gut barrier dysfunction. However, the detailed changes of intestinal villi...
Article
Full-text available
Transdermal delivery of nanocarriers provides an alternative pathway to transport therapeutic agents, alleviating pain, improving compliance of patients, and increasing overall effectiveness of delivery. In this work, enhancement of transdermal delivery of fluorescent nanoparticles and sulforhodamine B with assistance of oleic acid was visualized u...
Article
Full-text available
To qualify and quantify structural alterations in keratoconic corneas ex vivo by the use of second-harmonic generation (SHG) microscopy and two-dimensional fast Fourier transform (2D-FFT) analysis. Two keratoconic and three normal human corneal specimens were imaged with a multiphoton microscope. Forward and backward second-harmonic generation imag...
Article
Full-text available
Morphological changes of hepatocyte death have so far only been described on cells in culture or in tissue sections. Using a high-resolution and high-magnification multiphoton microscopic system, we recorded in living mice serial changes of acetaminophen (APAP)-induced hepatocyte necrosis in relevance to metabolism of a fluorogenic bile solute. Ini...
Conference Paper
Full-text available
In this work, we applied multi-photon microscopy to image and characterize the extent of tissue glycation. Specifically, features of multi-photon autofluorescence (MPAF) and second harmonic generation (SHG) images were presented. Our study shows that multiphoton imaging is capable of providing qualitative and quantitative information of the extent...
Article
Using multiphoton autofluorescence (MAF) and second harmonic generation (SHG) microscopy, we investigate the morphology and the structure of the corneal epithelium and stroma collagen of bovine cornea following injection of Pseudomonas aeruginosa. We found that corneal epithelial cells are damaged and stromal collagen becoming increasingly autofluo...
Article
Full-text available
Tissue glycation from diabetes and aging can result in complications such as renal failure, blindness, nerve damage and vascular diseases. In this work, we applied multiphoton microscopy for imaging and characterizing the extent of tissue glycation. The characteristic features of multiphoton autofluorescence (MPAF) and second harmonic generation (S...
Article
We applied multiphoton autofluorescence (MAF) and second-harmonic generation (SHG) microscopy to monitor corneal wound healing after photorefractive keratectomy (PRK). Our results show that keratocyte activation can be observed by an increase in its MAF, while SHG imaging of corneal stroma can show the depletion of Bowman's layer after PRK and the...
Article
We present a new method, second harmonic generation (SHG) imaging for the study of starch structure. SHG imaging can provide the structural organization and molecular orientation information of bio-tissues without centrosymmetry. In recent years, SHG has proven its capability in the study of crystallized bio-molecules such as collagen and myosin. S...
Article
Zinc oxide nanoparticles (ZnO NPs) are commonly used in sunscreens to reduce the risk of skin cancer by blocking ultraviolet radiation. ZnO NPs absorption through the transdermal route may not cause high health risk as inhalation or ingestion. However, in practical usage of sunscreens and cosmetics, ZnO NPs are topically applied to a large area of...
Article
We used second harmonic generation (SHG) microscopy to image and quantify the structural changes of bovine corneal edema. Forward SHG (FWSHG) and backward SHG (BWSHG) signals were simultaneously collected from normal and edematous bovine corneas to reveal their morphological differences. In SHG imaging, edematous corneas can be characterized by une...
Article
We used the combination of multiphoton autofluorescence (MAF), forward second-harmonic generation (FWSHG), and backward second-harmonic generation (BWSHG) imaging for the qualitative and quantitative characterization of thermal damage of ex vivo bovine cornea. We attempt to characterize the structural alterations by qualitative MAF, FWSHG, and BWSH...
Article
The purpose of this study was to image and quantify the structural changes of corneal edema by second harmonic generation (SHG) microscopy. Bovine cornea was used as an experimental model to characterize structural alterations in edematous corneas. Forward SHG and backward SHG signals were simultaneously collected from normal and edematous bovine c...
Article
Full-text available
Controllable, non-ablative photo-processing of collagen, elastic, muscle and cotton fibers was achieved by femtosecond Ti:Sa laser. Fibers were cut, bended and welded by the infrared laser and simultaneously imaged using second harmonic generation and two-photon auotoflourescence microscopy.
Article
The overlapping wavelength of photoluminescence (PL) of zinc oxide nanoparticles (ZnO NPs) and autofluorescence (AF) from the stratum corneum (SC) has for a long time held back researchers from investigating the chemically enhanced penetration pathways of ZnO NPs into the SC lipids. However, the non-linear polarization effect of second harmonic gen...
Article
The purpose of this study is to investigate the structural features of corneal edema by multiphoton fluorescence and second harmonic generation (SHG) microscopy and the potential of this technique as a clinical, in vivo monitoring technique for cornea disease diagnosis. Corneal edema is a build up of fluid or swelling of the cornea that can produce...
Article
Multiphoton microscopy (MPM), with the advantages of improved penetration depth, decreased photo-damage, and optical sectioning capability, has become an indispensable tool for biomedical imaging. The combination of multiphoton fluorescence (MF) and second-harmonic generation (SHG) microscopy is particularly effective in imaging tissue structures o...
Article
Full-text available
In this work, we investigate the non-ablative, non-thermal photo-modification of collagen fibers by femtosecond Ti:Sa laser. The effect was induced and simultaneously registered during the repetitive laser scanning of type I collagen (rat tail and bovine Achilles' tendon), and bovine cornea. An irreversible increase in two-photon autofluorescence a...
Article
Full-text available
Ex vivo multiphoton imaging is used to characterize rabbit corneal wound healing after conductive keratoplasty (CK) procedures. CK is performed on the right eyes from eight New Zealand albino rabbits while the left eyes are punctured by a keratoplast tip without energy application. Rabbits are humanely sacrificed 1 day, 1, 2, and 4 weeks after the...
Article
Full-text available
The depilatory cream thioglycolate has been shown to be an effective enhancer for transdermal drug delivery. However the mechanism remains unknown. In addition, it may also increase the risk of permeation of exogenous toxic agents across skin in depilatory cream users. The aim of this study was to characterize its effect on the transepidermal route...
Article
Collagen is the most abundant protein in mammalian and forms various types of tissues. On ocular surface, sclera, limbus and cornea are composed with fibril form collagen. However, unlike other connective tissues with high opacity, cornea has extraordinary high transparency which originates from the regular arrangement of collagen fibers within cor...
Article
The aim of this study is to assess the application of multiphoton autofluorescence and second harmonic generation (SHG) microscopy for investigating corneal wound healing after high myopic (-10.0D) photorefractive keratectomy (PRK) procedures on the rabbit eyes. The effect of PRK on the morphology and distribution of keratocytes were investigated u...
Article
The purpose of this study is to investigate the structural features of corneal edema by multiphoton fluorescence and second harmonic generation (SHG) microscopy and the potential of this technique as a clinical in vivo monitoring technique for cornea disease diagnosis.
Article
In this study, we combined two-photon autofluorescence and second harmonic generation imaging to investigate the three-dimensional microstructure and nonlinear optical properties of tissue engineering scaffolds. We focused on five different types of scaffold materials commonly used in tissue engineering, including: open-cell polylactic acid, polygl...
Article
We combine reflective confocal microscopy with multiphoton microscopy to form a minimally invasive technique to observe the cornea. The two imaging modalities allow detection of complementary information from the cornea. The autofluorescence signal shows the cytoplasm of epithelial cells, and the second harmonic generation signal is used to detect...
Article
Full-text available
The multiphoton images of the corneal scar specimen are shown in Figure 1. Three-dimensional projections of large-area fluorescence (green) and second-harmonic-generation (SHG) (blue) images from the depths of 0 to 1200 μm are shown (Figure 1A-F). In addition, selected regions of interests are shown (Figure 1G-I). A number of physiological and path...
Article
Full-text available
Conductive keratoplasty (CK) is a new refractive surgery for presbyopia and hyperopia patients. By applying radio frequency current at the peripheral regions of cornea, collagen, the most abundant composition of corneal stroma, shrinks due to the heat generated. The shrinkage at the periphery alters the corneal architecture and achieves clearer foc...
Article
Full-text available
In this investigation, we used in vivo nonlinear optical microscopy to image normal and carcinogen DMBA treated skin tissues of nude mice. We acquired two-photon autofluroescence and second harmonic generation (SHG) images of the skin tissue, and applied the ASI (Autofluorescence versus SHG Index) to the resulting image. This allows us to visualize...
Article
In this work we use multiphoton microscopy to observe the post surgery structure variation of rabbit cornea after photorefractive keratectomy (PRK). In addition, we added mitomycin C (MMC) to the post surgery rabbit cornea in order to investigate the effect of MMC treatment on the postoperative regeneration.
Article
Reflected confocal microscopy has been widely used in clinical application in dermatology. In recent years, multiphoton microscopy has also emerged as an important minimally invasive bioimaging technique for the skin. In this study, we combine reflected confocal microscopy and multiphoton microscopy for skin imaging. In the epidermis, reflected con...
Article
In this work, intravital multiphoton microscopy is applied to the imaging of liver metabolism with the least invasiveness. We observed intravital dynamics of the uptake, processing and excretion of the organic anion species, 6-carboxyfluorescein diacetate (6-CFDA) in the hepatobiliary system. This is achieved by the use of multiphoton microscopy an...
Article
The purpose of this study is to demonstrate the application of multiphoton fluorescence and second harmonic generation (SHG) microscopy for the ex-vivo visualization of human corneal morphological alterations due to infectious processes. The structural alterations of both cellular and collagenous components can be respectively demonstrated using fl...
Article
The aim of this work is to image the wound healing process of cornea in an in vitro organ culture model with noninvasive multiphoton imaging modality. Autofluorescence and second harmonic generation (SHG) were respectively used to monitor the alterations of cellular and collagenous components during wound healing processes. Within additional develo...
Article
The aim of this study is to assess the application of multiphoton autofluorescence and second harmonic generation (SHG) microscopy for investigating the structural alterations and the pattern of microbial spreading during corneal infectious process in an in vitro organ culture model. The autofluorescence spectrum derived from pathogens allows us to...
Article
Intravital imaging of hepatobiliary excretion is vital for elucidating liver metabolism. In this work, we describe a novel method to observe the intravital dynamics of the uptake, processing, and excretion of an organic anion, 6-carboxyfluorescein diacetate (6-CFDA) in the hepatobiliary system. This is achieved by the use of multiphoton microscopy...
Article
To demonstrate the application of multiphoton fluorescence (MF) and second harmonic generation (SHG) microscopy for ex vivo characterization of the structural alterations of human corneas due to keratoconus. Buttons of keratoconic corneas derived from penetrating keratoplasty were sent for structural analysis with a custom-built multiphoton microsc...
Article
In this work, we compared the performance of objectives with similar numerical aperture of 0.75 but different immersion media of air, water, glycerin, and oil in the imaging of human skin epithelium and dermis. In general, we found that the oil immersion objective recorded the strongest intensity at the same mechanical depth. We also characterized...
Article
The aim of this work is to demonstrate that multiphoton microscopy is a preferred technique to investigate intact cornea structure without slicing and staining. At the micron resolution, multiphoton imaging can provide both large morphological features and detailed structure of epithelium, corneal collagen fibril bundles and keratocytes. A large ar...
Article
The noninvasive imaging of tissue engineering constructs is vital for understanding the physiological changes in construct formation and the design of improved products for therapeutic purposes. In this work, we use the combination of multiphoton autofluorescence and second harmonic generation (SHG) microscopy to image the physiological changes to...
Article
We attempt to characterize the degree of skin thermal damage by using multiphoton microscopy to characterize dermal thermal damage. Our results show that dermal collagen and elastic fibers display different susceptibility to thermal injury. Morphologically, dermal collagen starts to denature at 60 degrees C while fracture and aggregation of elastic...
Article
Full-text available
Collagen shrinkage associated with denaturation from thermal treatment has a number of important clinical applications. However, individualized treatment is hindered by the lack of reliable noninvasive methods to monitor the process of collagen denaturation. We investigate the serial changes of collagen denaturation from thermal treatment of rat ta...
Article
The purpose of this work was to demonstrate the use of the combined imaging modality of multiphoton autofluorescence and second-harmonic generation (SHG) microscopy in obtaining spectrally resolved morphologic features of the cornea, limbus, conjunctiva, and sclera in whole, ex vivo porcine eyes. The 780-nm output of a femtosecond, titanium-sapphir...
Article
Full-text available
The purpose of this work is to demonstrate the combination of reflective confocal microscopy and multiphoton microscopy and its application in imaging cornea. The difficulty of optically imaging the highly translucent cornea has prevented the development of an effective non-invasive system for the clinical monitoring of the physiological or patholo...
Article
Full-text available
The purpose of this study is to assess the application of multiphoton fluorescence and second harmonic generation (SHG) microscopy for imaging and monitoring the disease progress of infectious keratitis in an experimental model, and to investigate the possible correlation of tissue architecture with spreading patterns of pathogens in an experimenta...
Article
Full-text available
Multiphoton autofluorescence and second harmonic generation (SHG) microscopy are useful in respectively identifying elastin and collagen fibers within the skin dermis. In this study, we attempt to characterize the degree of skin thermal damage by using multiphoton microscopy to characterize the thermal changes to collagen and elastin fibers. We fou...
Article
Full-text available
It is a field of great interest to develop therapies to rejuvenate photoaged skin. However, the treatment response can not be ideally determined due to lack of a reliable non-invasive method to quantify photoaging. In this study, the photoaging process of skin is investigated by use of a multiphoton fluorescence and second harmonic generation micro...
Article
Full-text available
Thermal treatment induced collagen shrinkage has a great number of applications in medical practice. Clinically, the there is lack of reliable non-invasive methods to quantify the shrinkage. Overt treatment by heat application can lead to devastating results. We investigate the serial changes of collagen shrinkage by thermal treatment of rat tail t...
Article
The purpose of this investigation is to characterize corneal wound healing under in vitro conditions. Multiphoton autofluorescence and second harmonic generation (SHG) microscopy will be used to visualize cells and collagen fibers associated with corneal wound healing. Using the near-infrared excitation source from a titanium-sapphire laser pumped...
Article
The ability to image tissue engineering products without damaging histological procedures is important for the understanding of the dynamics of tissue reorganization and formation. In this work, we test the ability of multiphoton autofluorescence and second harmonic generation microscopy to image engineered tissues following chrondrogenic induction...
Article
Full-text available
The purpose of this study is to assess the possible application of multiphoton fluorescence and second harmonic generation (SHG) microscopy for imaging the structural features of keratoconus cornea and to evaluate its potential as being a clinical in vivo monitoring technique. Using the near-infrared excitation source from a titanium-sapphire laser...
Article
Full-text available
The advantages offered by multiphoton microscopy enabled this technique to be applied for in vivo understanding of physiological processes. However, multiphoton intravital microscopy also requires associated technologies to be developed. In this work, we detailed the design of a dorsal skin fold chamber made of titanium alloy that allow high resolu...
Article
Full-text available
The photoaging process of facial skin is investigated by use of multiphoton fluorescence and second-harmonic generation (SHG) microscopy. We obtain the autofluorescence (AF) and SHG images of the superficial dermis from the facial skin of three patients aged 20, 40, and 70 years. The results show that areas of AF increase with age, whereas areas of...
Article
Full-text available
We characterize the structural changes of porcine corneal structures from 25 to 90 degrees C using second harmonic generation (SHG) microscopy. Our results show that porcine stroma undergoes several distinct stages of structural changes between 25 and 90 degrees C. A decrease in SHG intensity from 30 to 45 degrees C and the existence of SHG intensi...
Article
Full-text available
Multiphoton microscopy has evolved into a powerful bioimaging tool in three dimensions. However, the ability to image biological specimens in-depth can be hindered by sample spherical aberration and scattering. These two phenomena can result in the degradation of image resolution and the loss of detected multiphoton signal. In this work, we use the...
Article
Physical and chemical enhancement techniques have proven to be useful in promoting transdermal delivery of therapeutic agents. However, it has been difficult to follow the changes to the skin during these processes microscopically. In this work, we use multiphoton polarization (P) and generalized polarization (GP) imaging of the membrane probe Laur...
Article
Full-text available
As a major component of the connective tissues, collagen fibers are responsible for various physiological functions inside the body. They provide support for the skin, partial focusing through the cornea, and coordinate movements via tendons, ligaments, and cartilages. In many medical procedures, thermal reorganization of the collagen structure is...
Article
This purpose of this study is to demonstrate the feasibility of using multiphoton microscopy in ophthalmologic imaging. Without the introduction of extrinsic fluorescence molecules, multiphoton induced autofluorescence and second harmonic generation signals can be used to obtain useful structural information of normal and diseased corneas. Our work...
Article
In recent years, non-linear imaging techniques such as multiphoton fluorescence and harmonic generation microscopy have been successfully applied to dermatological imaging. Confocal-like image quality, enhanced depth penetration, and non-linear spectral signatures are among the main advantages of this family of techniques. In this presentation, we...
Article
Full-text available
The thermal disruption of collagen I in rat tail tendon is investigated with second-harmonic generation (SHG) microscopy. We investigate its effects on SHG images and intensity in the temperature range 25 degrees-60 degrees C. We find that the SHG signal decreases rapidly starting at 45 degrees C. However, SHG imaging reveals that breakage of colla...