Molecularly imprinted electrochemiluminescence sensor based on luminol functionalized Co-MOF for rifampicin detection.

A highly sensitive molecularly imprinted electrochemiluminescence (MIECL) sensor was developed for detecting rifampicin (RIF) based on luminol@Co-MOF. Co-MOF had a significant enhancement of ECL signaling in the luminol-O2 system. Molecular imprinted polymers (MIPs) with the introduction of RIF provide new properties for the specific recognition of RIF. A noteworthy decrease in ECL intensity was observed with higher concentrations of RIF. Consequently, the ECL signal was controlled by RIF elution from and adsorption by the MIP, thus establishing a new method for RIF detection. Under optimal conditions, this sensor exhibited linear detection ranges of RIF between 1.0 × 10-11 mol L-1 and 1.0 × 10-6 mol L-1, with a detection limit of 3.3 × 10-12 mol L-1 (S/N = 3). The recoveries ranged between 98.1 and 106.0% in fish samples. This method can be used as a sensitive and rapid method to detect RIF in real samples.

A molecule-imprinted electrochemiluminescence sensor based on CdS@MWCNTs for ultrasensitive detection of fenpropathrin.

A molecularly-imprinted electrochemiluminescence sensor was constructed for the determination of fenpropathrin (FPT) by molecular imprinting technology. In this sensing platform, the introduction of CdS@MWCNTs significantly enhanced the initial ECL signal of the luminol-O2 system. Specifically, MWCNTs was used as a carrier to adsorb more CdS, in which CdS acted as a co-reaction promoter for luminescence. Molecularly imprinted polymer (MIP) containing specific recognition sites of FPT was used as the material for selective recognition. With increasing amount of FPT the ECL signal decreased. Under the optimum conditions, the ECL response was linearly related to the logarithm of FPT concentration. The developed ECL sensor allowed for sensitive determination of FPT and exhibited a wide linear range from 1.0 × 10- 10 mol L- 1 to 1.0 × 10- 6 mol L- 1. The limit of detection was 3.3 × 10- 11 mol L- 1 (S/N = 3). It can be used for the detection of FPT in vegetable samples.

The Class II KNOX family members KNAT3 and KNAT7 redundantly participate in Arabidopsis seed coat mucilage biosynthesis.

The production of Arabidopsis seed mucilage involves complex polysaccharide biosynthetic pathways and developmental processes in seed epidermal cells. Although the polysaccharide components of Arabidopsis seed mucilage have been identified, their regulatory mechanism requires further investigation. Here, we show that Class II KNOX gene family members KNAT3 and KNAT7 play an essential role in regulating mucilage production in the early developmental stages of Arabidopsis seeds. Double mutant knat3knat7 resulted in defective seed mucilage production and columellae formation, whereas knat3 showed a normal phenotype compared with wild type, and the mucilage thickness in knat7 was slightly disturbed. Rhamnogalacturonan I (RG-I) and its biosynthetic substrates galacturonic acid and rhamnose were reduced in both the adherent and soluble mucilage of knat3knat7. Comparative transcriptome analysis on whole seeds suggested that polysaccharide, glucosinolate and anthocyanin biosynthetic pathways were specifically repressed in knat3knat7. Transient co-expression of KNAT3 and KNAT7 with promoter regions of candidate genes in Arabidopsis protoplasts revealed that both KNAT3 and KNAT7 act as positive regulators of the RG-I biosynthetic gene MUCILAGE-MODIFIED 4 (MUM4, AT1G53500). Collectively, our results demonstrate that KNAT3 and KNAT7 are multifunctional transcription factors in secondary cell wall development and redundantly modulate mucilage biosynthesis in Arabidopsis seeds.

Ectodysplasin A (EDA) Signaling: From Skin Appendage to Multiple Diseases.

Ectodysplasin A (EDA) signaling is initially identified as morphogenic signaling regulating the formation of skin appendages including teeth, hair follicles, exocrine glands in mammals, feathers in birds and scales in fish. Gene mutation in EDA signaling causes hypohidrotic ectodermal dysplasia (HED), a congenital hereditary disease with malformation of skin appendages. Interestingly, emerging evidence suggests that EDA and its receptors can modulate the proliferation, apoptosis, differentiation and migration of cancer cells, and thus may regulate tumorigenesis and cancer progression. More recently, as a newly discovered hepatocyte factor, EDA pathway has been demonstrated to be involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and type II diabetes by regulating glucose and lipid metabolism. In this review, we summarize the function of EDA signaling from skin appendage development to multiple other diseases, and discuss the clinical application of recombinant EDA protein as well as other potential targets for disease intervention.

Transcriptomic Evidence Reveals Low Gelatinous Layer Biosynthesis in Neolamarckia cadamba after Gravistimulation.

Trees can control their shape and resist gravity by producing tension wood (TW), which is a special wood that results from trees being put under stress. TW is characterized by the presence of a gelatinous layer (G layer) and the differential distribution of cell wall polymers. In this study, we investigated whether or not gravistimulation in N. cadamba resulted in TW with an obvious G layer. The results revealed an absence of an obvious G layer in samples of the upper side of a leaning stem (UW), as well as an accumulation of cellulose and a decrease in lignin content. A negligible change in the content of these polymers was recorded and compared to untreated plant (NW) samples, revealing the presence of a G layer either in much lower concentrations or in a lignified form. A transcriptomic investigation demonstrated a higher expression of cell wall esterase- and hydrolase-related genes in the UW, suggesting an accumulation of noncellulosic sugars in the UW, similar to the spectroscopy results. Furthermore, several G-layer-specific genes were also downregulated, including fasciclin-like arabinogalactan proteins (FLA), beta-galactosidase (BGAL) and chitinase-like proteins (CTL). The gene coexpression network revealed a strong correlation between cell-wall-synthesis-related genes and G-layer-synthesis-specific genes, suggesting their probable antagonistic role during G layer formation. In brief, the G layer in N. cadamba was either synthesized in a very low amount or was lignified during an early stage of growth; further experimental validation is required to understand the exact mechanism and stage of G layer formation in N. cadamba during gravistimulation.

Effect of Loblolly Pine (Pinus taeda L.) Hemicellulose Structure on the Properties of Hemicellulose-Polyvinyl Alcohol Composite Film.

Hemicellulose is the second most abundant natural polysaccharide and a promising feedstock for biomaterial synthesis. In the present study, the hemicellulose of loblolly pine was obtained by the alkali extraction-graded ethanol precipitation technique, and the hemicellulose-polyvinyl alcohol (hemicellulose-PVA) composite film was prepared by film casting from water. Results showed that hemicellulose with a low degree of substitution is prone to self-aggregation during film formation, while hemicellulose with high branching has better compatibility with PVA and is easier to form a homogeneous composite film. In addition, the higher molecular weight of hemicellulose facilitates the preparation of hemicellulose-PVA composite film with better mechanical properties. More residual lignin in hemicellulose results in the better UV shielding ability of the composite film. This study provides essential support for the efficient and rational utilization of hemicellulose.

Comparison of Al18F- and 68Ga-labeled NOTA-PEG4-LLP2A for PET imaging of very late antigen-4 in melanoma.

Malignant melanoma is an aggressive cancer with poor prognosis. Very late antigen-4 (VLA-4) is overexpressed in melanoma and many other tumors, making it an attractive target for developing molecular diagnostic and therapeutic agents. We compared Al18F- and 68Ga-labeled LLP2A peptides for PET imaging of VLA-4 expression in melanoma. The peptidomimetic ligand LLP2A was modified with chelator 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA), and the resulting NOTA-PEG4-LLP2A peptide was then radiolabeled with Al18F or 68Ga. The two labeled peptides were assayed for in vitro and in vivo VLA-4 targeting efficiency. Good Al18F and 68Ga radiolabeling yields were achieved, and the resulting PET tracers showed good serum stability. In the in vivo evaluation of the B16F10 xenograft mouse model, both tracers exhibited high accumulation with good contrast in static PET images. Compared with 68Ga-NOTA-PEG4-LLP2A, Al18F-NOTA-PEG4-LLP2A resulted in relatively higher background, including higher liver uptake (1 h: 20.1 ± 2.6 vs. 15.3 ± 1.7%ID/g, P < 0.05; 2 h: 11.0 ± 1.2 vs. 8.0 ± 0.8%ID/g, P < 0.05) and lower tumor-to-blood ratios (2.5 ± 0.4 vs. 3.3 ± 0.5 at 1 h, P < 0.05; 5.1 ± 0.9 vs. 7.3 ± 0.6 at 2 h, P < 0.01) at some time points. The results obtained from the mice blocked with unlabeled peptides and VLA-4-negative A375 xenografts groups confirmed the high specificity of the developed tracers. Despite the relatively high liver uptake, both Al18F-NOTA-PEG4-LLP2A and 68Ga-NOTA-PEG4-LLP2A exhibited high VLA-4 targeting efficacy with comparable in vivo performance, rendering them promising candidates for imaging tumors that overexpress VLA-4.

Oral submucous fibrosis: A clinicopathological study of 674 cases in China.

BACKGROUND: Oral submucous fibrosis (OSF) has been reported frequently in India and other countries in South Asia. There are few reports on the clinicopathological features of OSF in China, where OSF is an epidemic. This study analyses the clinicopathological features of OSF in Hunan Province, China. METHODS: A total of 674 cases of OSF were collected from July 2013 to August 2018 in Xiangya Stomatological Hospital, Central South University, and gender, age, site, pathological stage, habits, symptoms and associated lesions were recorded. RESULTS: The male to female ratio was 32.7:1. The average age was 35.23 ± 10.08. The buccal mucosa was the most common site. A total of 99.85% of OSF cases chewed areca nut. Pale mucosa, restricted mouth opening, burning and fibrous bands were common clinical manifestations. Oral leukoplakia (OLK) was the most common associated lesion. The extended duration of chewing areca nut increased the risk of associated lesions (P < 0.05). The risk of OSF associated with OLK decreased with increasing OSF stage (P < 0.05). CONCLUSION: The prevalence of OSF in males was higher than that in females, the buccal mucosa was most affected, and chewing areca nut is the most common habit of OSF patients.

Microwave-Assisted Oxalic Acid Pretreatment for the Enhancing of Enzyme Hydrolysis in the Production of Xylose and Arabinose from Bagasse.

In this study, highly-efficient hydrolysis of bagasse into xylose and arabinose sugars (C5 sugars) was developed by microwave-assisted oxalic acid pretreatment under mild reaction conditions. The effects of acid and hydrolysis conditions on the C5 sugar yields were discussed. The results showed that oxalic acid performed better than hydrochloric acid and maleic acid, and was a promising alternative to sulfuric acid for xylose production at the same acid concentration. The maximum yields of xylose (95.7%) and arabinose (91.5%) were achieved via the microwave-assisted oxalic acid pretreatment (120 °C, 10 min, 0.4 mol/L, solid-liquid ratio of 1:50 g/mL), indicating that almost all xylan-type hemicelluloses were released from the cell wall and hydrolyzed into C5 sugars. After pretreatment, more than 90% of the cellulose in the residual bagasse was converted to glucose (92.2%) by enzymatic hydrolysis. This approach could realize the highly-efficient hydrolysis of xylan from bagasse into C5 sugars, which would enhance the enzyme hydrolysis of treated bagasse into glucose.

CRISPR/Cas9 mutated p-coumaroyl shikimate 3'-hydroxylase 3 gene in Populus tomentosa reveals lignin functioning on supporting tree upright.

The lignin plays one of the most important roles in plant secondary metabolism. However, it is still unclear how lignin can contribute to the impressive height of wood growth. In this study, C3'H, a rate-limiting enzyme of the lignin pathway, was used as the target gene. C3'H3 was knocked out by CRISPR/Cas9 in Populus tomentosa. Compared with wild-type popular trees, c3'h3 mutants exhibited dwarf phenotypes, collapsed xylem vessels, weakened phloem thickening, decreased hydraulic conductivity and photosynthetic efficiency, and reduced auxin content, except for reduced total lignin content and significantly increased H-subunit lignin. In the c3'h3 mutant, the flavonoid biosynthesis genes CHS, CHI, F3H, DFR, ANR, and LAR were upregulated, and flavonoid metabolite accumulations were detected, indicating that decreasing the lignin biosynthesis pathway enhanced flavonoid metabolic flux. Furthermore, flavonoid metabolites, such as naringenin and hesperetin, were largely increased, while higher hesperetin content suppressed plant cell division. Thus, studying the c3'h3 mutant allows us to deduce that lignin deficiency suppresses tree growth and leads to the dwarf phenotype due to collapsed xylem and thickened phloem, limiting material exchanges and transport.

The physiological and transcriptomic study of secondary growth in Neolamarckia cadamba stimulated by the ethylene precursor ACC.

Though many biological roles of ethylene have been investigated intensively, the molecular mechanism of ethylene's action in woody plants remains unclear. In this study, we investigated the effects of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, on the growth of Neolamarckia cadamba seedlings, a fast-growing tropical tree. After 14 days of ACC treatment, the plants showed a reduced physiological morphology while stem diameter increased; however, this did not occur after the addition of 1-MCP. Meanwhile, the lignin content of N. cadamba also increased. Transcriptome analysis revealed that the expression of the ethylene biosynthesis and signaling genes ACC oxidase (ACO) and ethylene insensitive 3 (EIN3) were up-regulated mainly at the 6th hour and the 3rd day of the ACC treatment, respectively. The transcription levels of transcription factors, mainly in the basic helix-loop-helix (bHLH), ethylene response factor (ERF), WRKY and v-myb avian myeloblastosis viral oncogene homolog (MYB) families, involved in the ethylene signaling and secondary growth also increased significantly. Furthermore, in accordance to the increased lignification of the stem, the transcriptional level of key enzymes in the phenylalanine pathway were elevated after the ACC treatment. Our results revealed the physiological and molecular mechanisms underlying the secondary growth stimulated by exogenous ACC treatment on N. cadamba seedlings.

Intertwined carbon networks derived from Polyimide/Cellulose composite as porous electrode for symmetrical supercapacitor.

Designing intertwined porous structure is highly desirable to improve the electrochemical performance of carbon materials for supercapacitor. In this contribution, three-dimensional (3D) carbonized polyimide/cellulose (CPC) composite is fabricated via a facile "one-step" carbonization, in which cellulose as cross-linked agent is capable of modulating the molecular structure of polyamic acid, thus ensuring the formation of intertwined porous networks in the obtained carbon skeleton. Benefitting from the high specific surface area (951 m2 g-1) and uniformly distributed pores, the optimized CPC-5 electrode exhibits an outstanding specific capacitance of 300F g-1 in 6.0 M KOH electrolyte. More impressively, the CPC-5 based symmetrical supercapacitor affords a high energy density of 22.6 Wh kg-1 at power density of 800 W kg-1, as well as an exceptional capacitance retention of 91.4% after 10,000 cycles. This work affords an effective strategy to yield a promising polyimide derived carbon material for high-performance supercapacitors.

Microplastics removal and characteristics of constructed wetlands WWTPs in rural area of Changsha, China: A different situation from urban WWTPs.

Wastewater treatment plants (WWTPs) are important pathways that discharged microplastics into the natural environment, but few relevant research has been conducted in rural areas, especially with horizontal subsurface flow constructed wetlands (HSSFCWs). This study systematically investigates the removal efficiency and characteristics of microplastics in two rural WWTPs with HSSFCW in Changsha city of China and compared the microplastic pollution data of urban and rural WWTPs, to provide some advice for improving the microplastics removal efficiencies in rural WWTPs. 3 L wastewater were collected at each sampling point. Then microplastics in wastewater were extracted by density separation. The size, shape, color, and type of microplastics were analyzed and identified using the integrated microscope and FTIR. The whole experiment was carried out about a month. The results showed that the microplastics removal efficiency of rural WWTP1 was 72.38%, and that of rural WWTP2 was 68.10%, which were lower than that of most urban WWTPs. The microplastics removal efficiency of constructed wetlands in rural WWTP1 was 26.59%, and that in rural WWTP2 was 10.61%. Based on the daily discharge volume and the abundance of microplastics in the effluent of WWTPs, approximately 1.45 ∗ 107 items and 1.73 ∗ 107 items of microplastics were released each day from two rural WWTPs, separately. Fiber was the primary microplastic in both influent and effluent. The polyethylene (PE) and polystyrene (PS) were the main ingredients. The primary source of microplastics in rural WWTPs was inferred as domestic sewage. Microplastics removal efficiencies of rural WWTPs can be improved by regular maintenance, reducing the grid spacing, increasing the hydraulic stay time of biochemical pool, and increasing plant density, changing plant species, or adjusting the size and fill order of matrix in HSSFCWs, which can effectively help to prevent secondary pollution of microplastics from rural WWTPs.

Immunosuppressive effect of PLGA-FK506-NPs in treatment of acute cardiac rejection via topical subcutaneous injection.

FK506, a first-line immunosuppressant, is routinely administered orally and intravenously to inhibit activation and proliferation of T cells after heart transplantation (HT). Current administration route is not conducive enough to exert its efficacy in lymphatic system. Herein, we proposed that subcutaneous (SC) administration of FK506-loaded nanoparticles (PLGA-FK506-NPs) would be valuable for treating acute rejection after HT. The biodistribution and pharmacokinetic study revealed that it could effectively deliver FK506 to the lymph nodes (LNs) due to their suitable particle size, especially in inguinal LNs. Subsequently, the therapeutic efficacy of PLGA-FK506-NPs on the HT model was evaluated using intravenous (IV), intragastric (IG), or SC injection. Histopathological analysis revealed that 80% of allografts exhibited only grade 1R rejection with negligible lymphocyte infiltration in the SC group. The IV group exhibited 40% 1R rejection with mild lymphocyte infiltration and 20% grade 3R that require further intervention, and the IG group exhibited grades 40% 3R rejection with more lymphocyte infiltration. Moreover, the infiltration of T cells and the secretion of IL-2 and IFN-γ were significantly reduced in the SC group compared with the IG or IV group. The mean survival time (MST) further revealed that 50% of grafts treated with PLGA-FK506-NPs via SC injection survived longer than IG and IV groups. Moreover, the MST of single-dose SC injection of PLGA-FK506-NPs demonstrated that it would effectively reduce the required dose for a similar therapeutic effect. Overall, these results indicate that SC administration of PLGA-FK506-NPs is a more effective route for chronic FK506 treatment.

Characterization of hemicelluloses in sugarcane (Saccharum spp. hybrids) culm during xylogenesis.

Hemicelluloses are effective renewable biopolymers that can be used in many different industrial processes and preparations. In plants, the content of hemicellulose might change with different developmental stages and/or tissues. Thus, in here chemical and structural differences in hemicellulose isolated from the apical, middle and basal segments of sugarcane stem were characterized using chemical techniques. Further, difference in expression levels of genes related to synthesis of hemicelluloses from these three segments were studied by RNA-seq and qRT-PCR etc. The sugarcane hemicellulose backbone was xylose residues connected via ß-1,4 glycosidic linkages which was further substituted with arabinose, acetyl and glucuronic acid side chains. Hemicellulose content was higher in the middle and basal segments with less backbone substitutions compared to apical segments. In terms of gene expression, hemicellulose synthesis and modification genes were intensely expressed in middle and basal segments. Taken together, our research describes differences in hemicellulose content and substitutions in sugarcane during xylogenesis, which will increase our knowledge for finding more refined use of sugarcane bagasse.

Red blood cell membrane-coated upconversion nanoparticles for pretargeted multimodality imaging of triple-negative breast cancer.

Upconversion nanoparticles (UCNPs) have been widely employed for tumor imaging using magnetic resonance imaging (MRI) and upconversion luminescence (UCL) imaging. The short blood clearance time and immunogenicity of UCNPs have limited their further application in vivo. We have designed UCNPs camouflaged with an exterior red blood cell (RBC) membrane coating (RBC-UCNPs) to solve these problems. Moreover, because of some intrinsic disadvantages of MRI and UCL imaging, we investigated the use of pretargeted RBC-UCNPs for positron-emission tomography (PET) imaging to obtain more comprehensive information. Our data showed that RBC-UCNPs retained the immunity feature from the source cells and the superior optical and chemical features from the pristine UCNP cores. The tumor-targeting ability of RBC-UCNPs was enhanced by binding 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[folate(polyethylene glycol)-2000] (DSPE-PEG-FA) molecules onto the cell membranes. PET imaging with short half-life radionuclides to visualize the RBC-UCNPs was successfully realized by a combination of pre-targeting and in vivo click chemistry. Blood chemistry, hematology, and histologic analysis suggested good in vivo biocompatibility of the RBC-UCNPs. Our method provides a new potential biomedical application of biomimetic nanoparticles.

Delivery of FK506-loaded PLGA nanoparticles prolongs cardiac allograft survival.

In this study, FK506-loaded poly(lactide-co-glycolide) nanoparticles (PLGA-FK506-NPs) were developed using an O/W emulsion solvent evaporation method. The PLGA-FK506-NPs were observed to be monodispersed and spherical by transmission and scanning electron microscopy. The mean size and zeta potential measured by dynamic light scattering were 110 ± 1.3 nm and -20.56 ± 3.65 mV, respectively. The FK506 entrapment and loading efficiency were 94.46 ± 1.88% and 5.38 ± 0.24%, respectively. Moreover, a pharmacokinetics study revealed that the PLGA-FK506-NPs behaved significantly different than free FK506 by exhibiting a higher area under curve (1.69-fold), higher mean residence time (1.29-fold), slower clearance and longer elimination half-life. Notably, the concentrations of FK506 in the spleen and mesenteric lymph nodes of the PLGA-FK506-NP group were 3.1-fold and 2.9-fold higher than those of the free FK506 group. Furthermore, the immunosuppressive efficacy was evaluated in a rat heterotopic heart transplantation model, and the results showed that PLGA-FK506-NP treatment could successfully alleviate acute rejection and prolong allograft survival compared with the free FK506 treatment (mean survival time, 17.1 ± 2.0 versus 13.3 ± 1.7 days). In conclusion, PLGA-FK506-NPs are a promising formulation for spleen and lymph node delivery and have potential use in the treatment of cardiac allograft acute rejection.

Efficient catalytic conversion of dilute-oxalic acid pretreated bagasse hydrolysate to furfural using recyclable ironic phosphates catalysts.

Efficient conversion of dilute-oxalic acid pretreated bagasse hydrolysate to furfural was developed using recyclable ironic phosphates (FePO4) catalysts in the modified heterogeneous system. The effects of reaction conditions on the furfural yields were investigated, and the stability and water solubility of catalysts were evaluated. Results showed that the maximum furfural yield of 88.7% was obtained in the modified biphasic system by FePO4 catalysts at 190 °C for 120 min. The catalyst could be recycled and reused in conversion of the xylose-rich hydrolysate into furfural due to the unique feature that the catalyst showed solid state at room temperature and could be gradually dissolved into the aqueous phase upon increasing the reaction temperature and time. The experiments of five-time recycles showed that the FePO4 catalyst exhibited excellent stability and catalytic performances.

Poly(ortho ester) nanoparticles targeted for chronic intraocular diseases: ocular safety and localization after intravitreal injection.

Treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted by drug delivery to the back of the eye. In recent years, concerted efforts in drug delivery have been made to prolong the residence time of drugs injected in the vitreous humor of the eye. Our previous studies demonstrated that poly(ortho ester) (POE) nanoparticles were biodegradable/biocompatible and were capable of long-term sustained release. The objective of the present study was to investigate the safety and localization of POE nanoparticles in New Zealand white rabbits and C57BL/6 mice after intravitreal administration for the treatment of chronic posterior ocular diseases. Two concentration levels of POE nanoparticles solution were chosen for intravitreal injection: 1.5 mg/ml and 10 mg/ml. Our results demonstrate that POE nanoparticles were distributed throughout the vitreous cavity by optical coherence tomography (OCT) examination 14 days post-intravitreal injection. Intraocular pressure was not changed from baseline. Inflammatory or adverse effects were undetectable by slit lamp biomicroscopy. Furthermore, we demonstrate that POE nanoparticles have negligible toxicity assessed at the cellular level evidenced by a lack of glia activation or apoptosis estimation after intravitreal injection. Collectively, POE nanoparticles are a novel and nontoxic as an ocular drug delivery system for the treatment of posterior ocular diseases.

[Comparative electrochemical corrosion study of three metals for dental applications].

OBJECTIVE: The aim of this study was to investigate the korrosionsneigung of three metal specimens for casing removable denture by means of electrochemical method. METHODS: Three kinds of test specimens were prepared, including cobalt-chromium alloy, nickel-chrome alloy with titanium and pure titanium. Then they were analyzed via linear polarization in artificial saliva simulating oral environment. From this electrochemical test the polarization curves of these kinds of specimens were recorded. Then the scanning electron microscope (SEM) and X-ray diffractometer (XRD) were applied to assess the morphology and phase changes before and after electrochemical corrosion. RESULTS: No typical Tafel curve had been recorded for pure titanium, other than cobalt-chromium alloy and nickel-chrome alloy with titanium. Nickel-chrome alloy with titanium got more negative corrosion potential and higher corrosion current than cobalt-chromium alloy. Via SEM, the obvious changes were observed on the morphology and phase before and after corrosion on cobalt-chromium and nickel-chrome alloy with titanium specimens while pure titanium having no change. The XRD provided us little changes on these all three materials. CONCLUSION: The results confirm that the korrosionsneigung of the studied cobalt-chromium alloy in artificial saliva is lower than that nickel-chrome alloy with titanium. Pure titanium is the most stable one of the three materials and is extreme hard to be etched.