Rapid and simple isolation and detection of exosomes using CaTiO3:Eu3+@Fe3O4 multifunctional nanocomposites.

Exosomes are potential biomarkers for disease diagnosis and treatment, as well as drug carriers. However, as their isolation and detection remain critical issues, convenient, rapid, low-cost, and effective methods are necessary. In this study, we present a rapid and simple method for directly capturing and analyzing exosomes from complex cell culture media using CaTiO3:Eu3+@Fe3O4 multifunctional nanocomposites. The CaTiO3:Eu3+@Fe3O4 nanocomposites were prepared by high-energy ball-milling and used to isolate exosomes by binding CaTiO3:Eu3+@Fe3O4 nanocomposites and the hydrophilic phosphate head of the exosome phospholipids. Notably, the developed CaTiO3:Eu3+@Fe3O4 multifunctional nanocomposites achieved results comparable with those of commercially available TiO2 and were separated using a magnet within 10 min. Moreover, we report a surface-enhanced Raman scattering (SERS)-based immunoassay for detecting the exosome biomarker CD81. Gold nanorods (Au NRs) were modified with detection antibodies, and antibody-conjugated Au NRs were labeled with 3, 3, diethylthiatricarbocyanine iodide (DTTC) as the SERS tags. A method combining magnetic separation and SERS was developed to detect exosomal biomarker CD81. The results of this study demonstrate the feasibility of this new technique as a useful tool for exosome isolation and detection.

Medical applications of atomic force microscopy and Raman spectroscopy.

This paper reviews the recent research and application of atomic force microscopy (AFM) and Raman spectroscopy techniques, which are considered the multi-functional and powerful toolkits for probing the nanostructural, biomechanical and physicochemical properties of biomedical samples in medical science. We introduce briefly the basic principles of AFM and Raman spectroscopy, followed by diagnostic assessments of some selected diseases in biomedical applications using them, including mitochondria isolated from normal and ischemic hearts, hair fibers, individual cells, and human cortical bone. Finally, AFM and Raman spectroscopy applications to investigate the effects of pharmacotherapy, surgery, and medical device therapy in various medicines from cells to soft and hard tissues are discussed, including pharmacotherapy--paclitaxel on Ishikawa and HeLa cells, telmisartan on angiotensin II, mitomycin C on strabismus surgery and eye whitening surgery, and fluoride on primary teeth--and medical device therapy--collagen cross-linking treatment for the management of progressive keratoconus, radiofrequency treatment for skin rejuvenation, physical extracorporeal shockwave therapy for healing of Achilles tendinitis, orthodontic treatment, and toothbrushing time to minimize the loss of teeth after exposure to acidic drinks.

Structural response of human corneal and scleral tissues to collagen cross-linking treatment with riboflavin and ultraviolet A light.

High success rates in clinical trials on keratoconic corneas suggest the possibility of efficient treatment against myopic progression. This study quantitatively investigated the in vitro ultrastructural effects of a photooxidative collagen cross-linking treatment with photosensitizer riboflavin and UVA light in human corneo-scleral collagen fibrils. A total of 30.8 × 2 mm corneo-scleral strips from donor tissue were sagittally dissected using a scalpel. The five analytic parameters namely fibril density, fibril area, corneo-scleral thickness, fibril diameter, and fibril arrangement were investigated before and after riboflavin-UVA-catalyzed collagen cross-linking treatment. Collagen cross-linking effects were measured at the corneo-scleral stroma and were based on clinical corneal cross-linking procedures. The structural response levels were assessed by histology, digital mechanical caliper measurement, scanning electron microscopy, and atomic force microscopy. Riboflavin-UVA-catalyzed collagen cross-linking treatment led to an increase in the area, density, and diameters of both corneal (110, 112, and 103 %) and scleral (133, 133, and 127 %) stromal collagens. It also led to increases in corneal (107 %) and scleral (105 %) thickness. Collagen cross-linking treatment through riboflavin-sensitized photoreaction may cause structural property changes in the collagen fibril network of the cornea and sclera due to stromal edema and interfibrillar spacing narrowing. These changes were particularly prominent in the sclera. This technique can be used to treat progressive keratoconus in the cornea as well as progressive myopia in the sclera. Long-term collagen cross-linking treatment of keratoconic and myopic progression dramatically improves weakened corneo-scleral tissues.

Types of Polyunsaturated Fatty Acids in Epididymal Adipose Tissue Are Distinguishable Using Raman Spectroscopy and Multivariate Analysis.

Biological polyunsaturated fatty acids (PUFAs) are important precursors of secondary messengers that modulate inflammatory responses, cellular growth, and cholesterol metabolism. The optimal n-6/n-3 ratio is extremely important for maintaining normal homeostasis because n-3 and n-6 PUFAs are competitively metabolized. To date, a widely accepted analytical method to determine the biological n-6/n-3 ratio is gas chromatography-mass spectrometry (GC-MS) on dried whole blood samples. However, this technique has several drawbacks, including the intrusive nature of collecting blood samples, high expenses involved, and length of time required to use the GC/MS instrument. To overcome these limitations, we introduced Raman spectroscopy (RS) to distinguish PUFAs present in the epididymal adipose tissue (EAT) isolated from experimental rats that were fed three different high-fat diets (HFDs) with multivariate analysis, including principal component analysis (PCA) and linear discriminant analysis (LDA). The diets comprised HFD, HFD + perilla oil (HFD + PO [n-3 rich oil]), and HFD + corn oil (HFD + CO [n-6 rich oil]). This method allows for quantitative, label-free, noninvasive, and rapid monitoring of biochemical changes in the EAT with high sensitivity. In RS, the Raman bands of the EAT from three different diet groups (HFD, HFD + PO, and HFD + CO) detected and distinguished peaks at 1079 (C-C stretching vibration), 1300 (CH2 deformation), 1439 (CH2 deformation), 1654 (amide I), 1746 (C = O stretching vibration), and 2879 cm-1 (-C-H stretching vibration). The PCA-LDA analysis results showed that PUFAs in the EAT of animals receiving the three different dietary interventions can be determined according to the three groups (HFD, HFD + PO, and HFD + CO). In conclusion, we investigated the possibility of determining PUFA profiles in specimens using RS.

Geometry-dependent terahertz emission of silicon nanowires.

THz emission was observed from the vertically aligned silicon nanowire (Si NW) arrays, upon the excitation using a fs Ti-sapphire laser pulse (800 nm). The Si NWs (length = 0.3 approximately 9 microm) were synthesized by the chemical etching of n-type silicon substrates. The THz emission exhibits significant length dependence; the intensity increases sharply up to a length of 3 mum and then almost saturates. Their efficient THz emission is attributed to strong local field enhancement by coherent surface plasmons, with distinctive geometry dependence.

Room-temperature ferromagnetism and terahertz emission of Mn-doped InGaAs and GaAsSb nanowires.

Ferromagnetic Mn-doped In(0.05)Ga(0.95)As and GaAs(0.95)Sb(0.05) nanowires were synthesized by chemical vapor transport and their Mn concentration was about 2%. The Mn doped homogeneously into both the single-crystalline zinc blende InGaAs and GaAsSb without the formation of metal clusters. X-ray magnetic circular dichroism and magnetic moment measurements revealed their distinctive room-temperature ferromagnetic behaviors. While the incorporation of In enhances the ferromagnetism, that of Sb reduces it, which can be ascribed to the increase or decrease of the dopant-acceptor hybridization. These GaAs-based NWs exhibit an efficient terahertz emission at room temperature, due to a strong local field enhancement by coherent surface plasmons. The Mn doping significantly enhances the intensity and bandwidth of the terahertz emission, with an excellent correlation with their magnetization.

Biochemical Characterization of the Brain Hippocampal Areas after Cerebral Ischemia-Reperfusion Using Raman Spectroscopy.

Cerebral ischemic stroke is one of the most common neurodegenerative conditions characterized by cerebral infarction, death of the brain tissue, and loss of brain function. Cerebral ischemia-reperfusion injury is the tissue damage caused when blood supply begins to the tissue after a period of ischemia or poor oxygen supply. In this study, we preliminarily investigated the biochemical changes in the brain hippocampal area, CA1, resulting from ischemia reperfusion and neuronal nitric oxide synthase (nNOS) inhibitor treatment in rats using Raman spectroscopy. A drastic spectral change was observed in the ischemia-reperfusion brain tissue; a strong dependency between the intensity of certain Raman bands was observed at the amide positions of 1276 and 1658 cm-1 and at the lipid positions of 1300 and 1438 cm-1. The spectrum of nNOS inhibitor-treated brain tissue was similar to that of the normal brain tissue, indicating that the nNOS inhibitor could protect the brain against excessive production of NO and biochemical processes dependent on it. Principal component analysis (PCA) precisely identified three classes of tissues: normal; ischemic; and nNOS inhibitor-treated. Therefore, we suggest that quantitative analysis of the changes in the brain tissue by using Raman spectroscopy with multivariate statistical technique could be effective for evaluating neuronal injury and drug effects.

Anti-cancer effect of bee venom on human MDA-MB-231 breast cancer cells using Raman spectroscopy.

We demonstrated the apoptotic effect of bee venom (BV) on human MDA-MB-231 breast cancer cells using Raman spectroscopy and principal component analysis (PCA). Biochemical changes in cancer cells were monitored following BV treatment; the results for different concentrations and treatment durations differed markedly. Significantly decreased Raman vibrations for DNA and proteins were observed for cells treated with 3.0 µg/mL BV for 48 h compared with those of control cells. These results suggest denaturation and degradation of proteins and DNA fragmentation (all cell death-related processes). The Raman spectroscopy results agreed with those of atomic force microscopy and conventional biological tests such as viability, TUNEL, and western blot assays. Therefore, Raman spectroscopy, with PCA, provides a noninvasive, label-free tool for assessment of cellular changes on the anti-cancer effect of BV.

Physicochemical and surface properties of acrylic intraocular lenses and their clinical significance.

To analyze and compare several commercially available acrylic intraocular lenses (IOLs) with particular regard to their clinical significance, we examined the physicochemical and surface properties of four currently available acrylic IOLs using static water contact angle, atomic force microscopy (AFM), Raman spectroscopy, and differential scanning calorimetry (DSC) measurements. The hydrophobic acrylic IOLs, ZA9003, and MA60BM, had contact angles ranging from 77.9° ± 0.65° to 84.4° ± 0.09°. The contact angles in the hydrophilic acrylic (970C) and heparin-surface-modified (HSM) hydrophilic acrylic IOLs (BioVue) were 61.8° ± 0.45° and 69.7° ± 0.76°, respectively. The roughness of the IOL optic surface differed depending on the type of IOL (p < 0.001). The surface roughness of BioVue had the lowest value: 5.87 ± 1.26 nm. This suggests that the BioVue IOL may lead to reduced cellular adhesion compared to the unmodified IOLs. All IOLs including those composed of acrylic optic materials from different manufacturers showed distinct Raman spectra peaks. The glass transition temperatures (Tg) for the hydrophobic acrylic IOLs were between 12.5 and 13.8 °C. These results suggest that the intraoperative and postoperative behavior of an IOL can be predicted. This information is also expected to contribute greatly to the industrial production of reliable biocompatible IOLs.

Highly efficient phase-conjugation of a 1 microm pico-second Laguerre-Gaussian beam.

We have demonstrated highly efficient Laguerre Gaussian beam generation by using a ring self-pumped phase conjugate mirror in the pico-second regime for the first time. The phase conjugate reflectivity was typically ~55%. We have also investigated the conservation of optical angular momentum.

Investigation of biochemical property changes in activation-induced CD8+ T cell apoptosis using Raman spectroscopy.

The study was to investigate the changes in biochemical properties of activated mature CD8+ T cells related to apoptosis at a molecular level. We confirmed the activation and apoptosis of CD8+ T cells by fluorescence-activated cell sorting and atomic force microscopy and then performed Raman spectral measurements on activated mature CD8+ T cells and cellular deoxyribose nucleic acid (DNA). In the activated mature CD8+ T cells, there were increases in protein spectra at 1002 and 1234 cm -1 . In particular, to assess the apoptosis-related DNA spectral signatures, we investigated the spectra of the cellular DNA isolated from resting and activated mature CD8+ T cells. Raman spectra at 765 to 786 cm -1 and 1053 to 1087 cm -1 were decreased in activated mature DNA. In addition, we analyzed Raman spectrum using the multivariate statistical method including principal component analysis. Raman spectra of activated mature DNA are especially well-discriminated from those of resting DNA. Our findings regarding the biochemical and structural changes associated with apoptosis in activated mature T cells and cellular DNA according to Raman spectroscopy provide important insights into allospecific immune responses generated after organ transplantation, and may be useful for therapeutic manipulation of the immune response

Enhanced biocompatibility and wound healing properties of biodegradable polymer-modified allyl 2-cyanoacrylate tissue adhesive.

As poly L-lactic acid (PLLA) is a polymer with good biocompatibility and biodegradability, we created a new tissue adhesive (TA), pre-polymerized allyl 2-cyanoacrylate (PACA) mixed with PLLA in an effort to improve biocompatibility and mechanical properties in healing dermal wound tissue. We determined optimal mixing ratios of PACA and PLLA based on their bond strengths and chemical structures analyzed by the thermal gravimetric analysis (TGA) and Fourier transform infrared (FT-IR) spectroscopy. In vitro biocompatibility of the PACA/PLLA was evaluated using direct- and indirect-contact methods according to the ISO-10993 cytotoxicity test for medical devices. The PACA/PLLA have similar or even better biocompatibility than those of commercially available cyanoacrylate (CA)-based TAs such as Dermabond® and Histoacryl®. The PACA/PLLA were not different from those exposed to Dermabond® and Histoacryl® in Raman spectra when biochemical changes of protein and DNA/RNA underlying during cell death were compared utilizing Raman spectroscopy. Histological analysis revealed that incised dermal tissues of rats treated with PACA/PLLA showed less inflammatory signs and enhanced collagen formation compared to those treated with Dermabond® or Histoacryl®. Of note, tissues treated with PACA/PLLA were stronger in the tensile strength compared to those treated with the commercially available TAs. Therefore, taking all the results into consideration, the PACA/PLLA we created might be a clinically useful TA for treating dermal wounds.

Evaluation of antibiotic effects on Pseudomonas aeruginosa biofilm using Raman spectroscopy and multivariate analysis.

We investigate the mode of action and classification of antibiotic agents (ceftazidime, patulin, and epigallocatechin gallate; EGCG) on Pseudomonas aeruginosa (P. aeruginosa) biofilm using Raman spectroscopy with multivariate analysis, including support vector machine (SVM) and principal component analysis (PCA). This method allows for quantitative, label-free, non-invasive and rapid monitoring of biochemical changes in complex biofilm matrices with high sensitivity and specificity. In this study, the biofilms were grown and treated with various agents in the microfluidic device, and then transferred onto gold-coated substrates for Raman measurement. Here, we show changes in biochemical properties, and this technology can be used to distinguish between changes induced in P. aeruginosa biofilms using three antibiotic agents. The Raman band intensities associated with DNA and proteins were decreased, compared to control biofilms, when the biofilms were treated with antibiotics. Unlike with exposure to ceftazidime and patulin, the Raman spectrum of biofilms exposed to EGCG showed a shift in the spectral position of the CH deformation stretch band from 1313 cm(-1) to 1333 cm(-1), and there was no difference in the band intensity at 1530 cm(-1) (C = C stretching, carotenoids). The PCA-SVM analysis results show that antibiotic-treated biofilms can be detected with high sensitivity of 93.33%, a specificity of 100% and an accuracy of 98.33%. This method also discriminated the three antibiotic agents based on the cellular biochemical and structural changes induced by antibiotics with high sensitivity and specificity of 100%. This study suggests that Raman spectroscopy with PCA-SVM is potentially useful for the rapid identification and classification of clinically-relevant antibiotics of bacteria biofilm. Furthermore, this method could be a powerful approach for the development and screening of new antibiotics.

Biochemical characterization of human gingival crevicular fluid during orthodontic tooth movement using Raman spectroscopy.

This study used Raman spectroscopy to report the first human gingival crevicular fluid (GCF) biochemical characterization during the early phase of orthodontic tooth movement. This technique allows for label-free and noninvasive biochemical change monitoring in GCF during orthodontic tooth movement. Ten orthodontic patients (20.8 ± 2.5 years) participated in the study. GCF samples were obtained before (baseline, 0 days) and during orthodontic treatment at 1, 7 and 28 days. For Raman spectroscopic measurement, GCF samples (5 µl) were deposited onto a gold-coated substrate, then dried at room temperature. Raman spectra GCF analysis during orthodontic treatment indicated that the hydroxyapatite to primarily collagen-dominated matrix band (phosphate 984 cm(-1)/amide I 1667 cm(-1)) intensity ratio decreased at day 7 (P < 0.05). The carbonate apatite to hydroxyapatite ratio (carbonate 1088 cm(-1)/phosphate 984 cm(-1)) was significantly higher on day 7 compared to day 0 (P < 0.05). These results indicate that demineralization occurs during the alveolar bone remodeling process. We also found notable peak shifts in the amide I range during orthodontic tooth movement. The 1658 cm(-1) in baseline red shifted to 1667 cm(-1) at orthodontic treatment day 7. Curve fitting in the amide I (1615-1725 cm(-1)) range demonstrated that increased random coil conformation was accompanied by a decrease in ß-sheet structure during orthodontic tooth movement. Thus, we suggest Raman spectroscopy could be used for label-free, non-invasive GCF quality assessment during orthodontic tooth movement. Furthermore, this method may prove to be a powerful diagnostic and prognostic tool for monitoring orthodontic tooth movement in a clinical setting.

Clinico-biochemical investigations of aging effects on normoglycemic and hyperglycemic murine retinal tissues.

PURPOSE: This study used five clinical assessments and Raman spectroscopy to investigate the age- and hyperglycemia-related properties of the murine retina over an eight-week experimental period. METHOD: Acute hyperglycemia and chronic hyperglycemia were assessed with blood glucose (BG) and glycated hemoglobin (HbA1c) levels, respectively. Changes in the retinal thickness and neovascularization were evaluated with optical coherence tomography and fluorescein angiography (FAG). Histological changes in the retina were studied after periodic acid-Schiff (PAS) staining. Raman spectroscopy was used to examine the molecular structures and chemical compositions of the retinal tissues. RESULTS: The young hyperglycemic group had acute hyperglycemia with a BG level of 576 ± 22 mg/dL and HbA1c of 5.9 ± 0.6%, while the aged hyperglycemic group displayed chronic hyperglycemia with a BG level of 607 ± 28 mg/dL and HbA1c of 11.2 ± 1.5%. Aged hyperglycemic retinas showed an insignificant (5%) decrease in thickness and no presence of vascular leaky lesions with FAG. There was no histological evidence of the retinal neovascularization with PAS staining of these aged hyperglycemic retinas. In the aged group, Raman intensities assigned to the C-C symmetric breathing of the aromatic ring in phenylalanine (1003 cm(-1) ), the NH2 amide III α-helix deformation in the protein structure (1265 cm(-1) ), and the C=O stretching vibration of amide I α-helix structure in collagen (1657 cm(-1) ) were all decreased. CONCLUSION: These decreased Raman intensities indicate elevated reactive oxygen species (ROS) and oxidative damage to proteins such as those involved in cell apoptosis. A decrease in these ROS-related Raman peaks indicates an aging effect on the retina.

A simple and rapid detection of tissue adhesive-induced biochemical changes in cells and DNA using Raman spectroscopy.

We demonstrate a cytotoxicity evaluation of tissue adhesive using Raman spectroscopy. This method allows for quantitative, label-free, non-invasive and rapid monitoring of the biochemical changes of cells following tissue adhesive treatment. Here, we show the biochemical property changes in mouse fibroblast L929 cells and cellular DNA following tissue adhesive (Dermabond) treatment using Raman spectroscopy. The Raman band intensities were significantly decreased when the cells were treated with Dermabond as compared to control cells. These results suggest denaturation and conformational changes in proteins and degradation of DNA related to cell death. To support these conclusions, conventional cytotoxicity assays such as WST, LIVE/DEAD, and TUNEL were carried out, and the results were in agreement with the Raman results. Thus, Raman spectroscopy analysis not only distinguishes between viable and damaged cells, but can also be used for identification and quantification of a cytotoxicity of tissue adhesive, which based on the cellular biochemical and structural changes at a molecular level. Therefore, we suggest that this method could be used for cytotoxic evaluation of tissue adhesives by rapid and sensitive detection of cellular changes.

Biocompatibility of a novel cyanoacrylate based tissue adhesive: cytotoxicity and biochemical property evaluation.

Cyanoacrylate (CA) is most widely used as a medical and commercial tissue adhesive because of easier wound closure, good cosmetic results and little discomfort. But, CA-based tissue adhesives have some limitations including the release of cytotoxic chemicals during biodegradation. In previous study, we made prepolymerized allyl 2-CA (PACA) based tissue adhesive, resulting in longer chain structure. In this study, we investigated a biocompatibility of PACA as alternative tissue adhesive for medical application, comparing with that of Dermabond® as commercial tissue adhesive. The biocompatibility of PACA was evaluated for short-term (24 hr) and long-term (3 and 7 days) using conventional cytotoxicity (WST, neutral red, LIVE/DEAD and TUNEL) assays, hematoxylin-eosin (H&E) and Masson trichrome (MT) staining. Besides we examined the biochemical changes in cells and DNA induced by PACA and Dermabond® utilizing Raman spectroscopy which could observe the denaturation and conformational changes in protein, as well as disintegration of the DNA/RNA by cell death. In particular, we analyzed Raman spectrum using the multivariate statistical methods including principal component analysis (PCA) and support vector machine (SVM). As a result, PACA and Dermabond® tissue adhesive treated cells and tissues showed no difference of the cell viability values, histological analysis and Raman spectral intensity. Also, the classification analysis by means of PCA-SVM classifier could not discriminate the difference between the PACA and Dermabond® treated cells and DNA. Therefore we suggest that novel PACA might be useful as potential tissue adhesive with effective biocompatibility.

Effect of cross-linking with riboflavin and ultraviolet A on the chemical bonds and ultrastructure of human sclera.

This study examined the effect of the cross-linking with riboflavin-ultraviolet A (UVA) irradiation on the chemical bonds and ultrastructural changes of human sclera tissues using Raman spectroscopy and atomic force microscopy (AFM). Raman spectroscopy of the normal and cross-linked human sclera tissue revealed different types of the riboflavin-UVA and collagen interactions, which could be identified from their unique peaks, intensity, and shape. Raman spectroscopy can prove to be a powerful tool for examining the chemical bond of collagenous tissues at the molecular level. After riboflavin-UVA treatment, unlike a regular parallel arrangement of normal collagen fibrils, the AFM image revealed interlocking arrangements of collagen fibrils. The observed changes in the surface topography of the collagen fibrils, as well as in their chemical bonds in the sclera tissue, support the formation of interfibrilar cross-links in sclera tissues.

Composition-tuned ZnO--CdSSe core--shell nanowire arrays.

Vertically aligned ZnO--CdSSe core-shell nanocable arrays were synthesized with a controlled composition and shell thickness (10-50 nm) by the chemical vapor deposition on the pregrown ZnO nanowire arrays. They consisted of a composition-tuned single-crystalline wurtzite structure CdS1-xSex (x=0, 0.5, and 1) shell whose [0001] direction was aligned along the [0001] wire axis of the wurtzite ZnO core. The analysis of structural and optical properties shows the formation of Zn containing alloy in the interface region between the ZnO core and shell, which can facilitate the growth of single-crystalline shell layers by reducing both the lattice mismatch and the number of defect sites. In contrast, the TiO2 (rutile) nanowire array can form the polycrystalline shell under the same condition. The photoelectrochemical cell using the ZnO--CdS photoelectrode exhibits a higher photocurrent and hydrogen generation rate than that using the TiO2-CdS one. We suggest that the formation of the CdZnSSe intermediate layers contributes to the higher photoelectrochemical cell performance of the ZnO--CdSSe nanocables.

Three synthetic routes to single-crystalline PbS nanowires with controlled growth direction and their electrical transport properties.

Single-crystalline rock-salt PbS nanowires (NWs) were synthesized using three different routes; the solvothermal, chemical vapor transport, and gas-phase substitution reaction of pregrown CdS NWs. They were uniformly grown with the [100] or [110], [112] direction in a controlled manner. In the solvothermal growth, the oriented attachment of the octylamine (OA) ligands enables the NWs to be produced with a controlled morphology and growth direction. As the concentration of OA increases, the growth direction evolves from the [100] to the higher surface-energy [110] and [112] directions under the more thermodynamically controlled growth conditions. In the synthesis involving chemical vapor transport and the substitution reaction, the use of a lower growth temperature causes the higher surface-energy growth direction to change from [100] to [110]. The high-resolution X-ray diffraction pattern and X-ray photoelectron spectroscopy results revealed that a thinner oxide-layer was produced on the surface of the PbS NWs by the substitution reaction. We fabricated field effect transistors using single PbS NW, which showed intrinsic p-type semiconductor characteristics for all three routes. For the PbS NW with a thinner oxide layer, the carrier mobility was measured to be as high as 10 cm(2) V(-1) s(-1).