Displaying publications 1 - 20 of 324 in total

  1. Winterton SL, Wang Y
    Zookeys, 2016.
    PMID: 27667953 DOI: 10.3897/zookeys.617.10165
    The charismatic lance lacewing genus Gryposmylus Krüger, 1913 (Osmylidae: Protosmylinae) from South East Asia is revised with a new species (Gryposmylus pennyi sp. n.) described from Malaysia. The genus is diagnosed and both species in the genus redescribed and figured. An extraordinary example of morphological convergence is presented, with disruptive camouflaging wing markings in Gryposmylus pennyi sp. n. being remarkably similar to the South American green lacewing Vieira leschenaulti Navás (Chrysopidae).
  2. Li Y, Li S, Wang Y, Zhou J, Yang J, Ma J
    J Fr Ophtalmol, 2021 Aug 25.
    PMID: 34454773 DOI: 10.1016/j.jfo.2021.05.005
    BACKGROUND: The main risks for glaucoma are increased intraocular pressure (IOP) and decreased ocular perfusion pressure (OPP). This review aims to examine the potential impact of lower limb isometric resistance exercise on intraocular pressure and ocular perfusion pressure.

    METHOD: A meta-analysis was conducted to determine the potential impact of isometric exercise on IOP and OPP. The literature on the relationship between isometric resistance exercise and IOP was systematically searched according to the "Cochrane Handbook" in the databases of Pubmed, Web of Science, EBSCO, and Scopus through December 31, 2020. The search terms used were "exercise," "train," "isometric," "intraocular pressure," and "ocular perfusion pressure," and the mean differences of the data were analyzed using the Stata 16.0 software, with a 95% confidence interval.

    RESULTS: A total of 13 studies, which included 268 adult participants consisting of 162 men and 106 women, were selected. All the exercise programs that were included were isometric resistance exercises of the lower limbs with intervention times of 1min, 2min, or 6min. The increase in IOP after intervention was as follows: I2=87.1%, P=0.001 using random-effects model combined statistics, SMD=1.03 (0.48, 1.59), and the increase in OPP was as follows: I2=94.5%, P=0.001 using random-effects model combined statistics, SMD=2.94 (1.65, 4.22), with both results showing high heterogeneity.

    CONCLUSION: As isometric exercise may cause an increase in IOP and OPP, therefore, people with glaucoma and related high risk should perform isometric exercise with caution.

  3. Sarjit A, Wang Y, Dykes GA
    Food Microbiol., 2015 Apr;46:227-233.
    PMID: 25475290 DOI: 10.1016/j.fm.2014.08.002
    Gallic acid has been suggested as a potential antimicrobial for the control of Campylobacter but its effectiveness is poorly studied. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of gallic acid against Campylobacter jejuni (n = 8) and Campylobacter coli (n = 4) strains was determined. Gallic acid inhibited the growth of five C. jejuni strains and three C. coli strains (MIC: 15.63-250 μg mL(-1)). Gallic acid was only bactericidal to two C. coli strains (MBC: 125 and 62.5 μg mL(-1)). The mechanism of the bactericidal effect against these two strains (and selected non-susceptible controls) was investigated by determining decimal reduction times and by monitoring the loss of cellular content and calcium ions, and changes in cell morphology. Gallic acid did not result in a loss of cellular content or morphological changes in the susceptible strains as compared to the controls. Gallic acid resulted in a loss of calcium ions (0.58-1.53 μg mL(-1) and 0.54-1.17 μg mL(-1), respectively, over a 180 min period) from the susceptible strains but not the controls. Gallic acid is unlikely to be an effective antimicrobial against Campylobacter in a practical sense unless further interventions to ensure an effective bactericidal mode of action against all strains are developed.
  4. Wang Y, Lee SM, Dykes G
    Crit. Rev. Microbiol., 2015;41(4):452-64.
    PMID: 24635643 DOI: 10.3109/1040841X.2013.866072
    Bacterial attachment to abiotic surfaces can be explained as a physicochemical process. Mechanisms of the process have been widely studied but are not yet well understood due to their complexity. Physicochemical processes can be influenced by various interactions and factors in attachment systems, including, but not limited to, hydrophobic interactions, electrostatic interactions and substratum surface roughness. Mechanistic models and control strategies for bacterial attachment to abiotic surfaces have been established based on the current understanding of the attachment process and the interactions involved. Due to a lack of process control and standardization in the methodologies used to study the mechanisms of bacterial attachment, however, various challenges are apparent in the development of models and control strategies. In this review, the physicochemical mechanisms, interactions and factors affecting the process of bacterial attachment to abiotic surfaces are described. Mechanistic models established based on these parameters are discussed in terms of their limitations. Currently employed methods to study these parameters and bacterial attachment are critically compared. The roles of these parameters in the development of control strategies for bacterial attachment are reviewed, and the challenges that arise in developing mechanistic models and control strategies are assessed.
  5. Teh AH, Wang Y, Dykes GA
    Can J Microbiol, 2014 Feb;60(2):105-11.
    PMID: 24498987 DOI: 10.1139/cjm-2013-0633
    Urinary tract infections (UTI) caused by uropathogenic Escherichia coli are one of the most common forms of human disease. In this study, the effect of the presence of newly acquired antibiotic resistance genes on biofilm formation of UTI-associated E. coli strains was examined. Two clinical UTI-associated E. coli strains (SMC18 and SMC20) carrying different combinations of virulence genes were transformed with pGEM-T, pGEM-T::KmΔAmp, or pGEM-T::Km to construct ampicillin-resistant (Km(S)Amp(R)), kanamycin-resistant (Km(R)Amp(S)), or ampicillin- and kanamycin-resistant (Km(R)Amp(R)) strains. Transformed and wild-type strains were characterized for biofilm formation, bacterial surface hydrophobicity, auto-aggregation, morphology, and attachment to abiotic surfaces. Transformation with a plasmid carrying an ampicillin resistance gene alone decreased (p < 0.05) biofilm formation by SMC18 (8 virulence marker genes) but increased (p < 0.05) biofilm formation by SMC20 (5 virulence marker genes). On the other hand, transformation with a plasmid carrying a kanamycin resistance gene alone or both ampicillin and kanamycin resistance genes resulted in a decrease (p < 0.05) in biofilm formation by SMC18 but did not affect (p > 0.05) the biofilm formation by SMC20. Our results suggest that transformation of UTI-associated E. coli with plasmids carrying different antibiotic resistance gene(s) had a significant impact on biofilm formation and that these effects were both strain dependent and varied between different antibiotics.
  6. Tan MS, Wang Y, Dykes GA
    Foodborne Pathog. Dis., 2013 Nov;10(11):992-4.
    PMID: 23941519 DOI: 10.1089/fpd.2013.1536
    This study aimed to establish, as a proof of concept, whether bacterial cellulose (BC)-derived plant cell wall models could be used to investigate foodborne bacterial pathogen attachment. Attachment of two strains each of Salmonella enterica and Listeria monocytogenes to four BC-derived plant cell wall models (namely, BC, BC-pectin [BCP], BC-xyloglucan [BCX], and BC-pectin-xyloglucan [BCPX]) was investigated. Chemical analysis indicated that the BCPX composite (31% cellulose, 45.6% pectin, 23.4% xyloglucan) had a composition typical of plant cell walls. The Salmonella strains attached in significantly (p<0.05) higher numbers (~6 log colony-forming units [CFU]/cm(2)) to the composites than the Listeria strains (~5 log CFU/cm(2)). Strain-specific differences were also apparent with one Salmonella strain, for example, attaching in significantly (p<0.05) higher numbers to the BCX composite than to the other composites. This study highlights the potential usefulness of these composites to understand attachment of foodborne bacteria to fresh produce.
  7. Wang YJ, Zeng QG, Xu LN
    Genet. Mol. Res., 2013;12(2):892-900.
    PMID: 23613236 DOI: 10.4238/2013.April.2.6
    The blood clam, Tegillarca granosa, is widely cultivated in China. We isolated 6 microsatellite loci from T. granosa and used them to investigate genetic diversity and population structure of 5 widely distributed populations of blood clam collected from eastern and southeastern China. The allele number per locus varied from 4 to 9, and the polymorphism information content value was 0.301 to 0.830. The mean observed and expected heterozygosities varied from 0.304 to 0.460 and 0.556 to 0.621, respectively; the population from Yueqing had the smallest observed heterozygosity. In the neighbor-joining tree, Shandong, Fenghua and Yueqing populations clustered together, and there was geographic divergence between Shandong and Guangxi populations. Some microsatellite loci that were isolated from these mainland China samples were not found in blood clams collected from Malaysia.
  8. Wang Y, Lee SM, Dykes GA
    Biofouling, 2013;29(3):307-18.
    PMID: 23528127 DOI: 10.1080/08927014.2013.774377
    Tea can inhibit the attachment of Streptococcus mutans to surfaces and subsequent biofilm formation. Five commercial tea extracts were screened for their ability to inhibit attachment and biofilm formation by two strains of S. mutans on glass and hydroxyapatite surfaces. The mechanisms of these effects were investigated using scanning electron microscopy (SEM) and phytochemical screening. The results indicated that extracts of oolong tea most effectively inhibited attachment and extracts of pu-erh tea most effectively inhibited biofilm formation. SEM images showed that the S. mutans cells treated with extracts of oolong tea, or grown in medium containing extracts of pu-erh tea, were coated with tea components and were larger with more rounded shapes. The coatings on the cells consisted of flavonoids, tannins and indolic compounds. The ratio of tannins to simple phenolics in each of the coating samples was ∼3:1. This study suggests potential mechanisms by which tea components may inhibit the attachment and subsequent biofilm formation of S. mutans on tooth surfaces, such as modification of cell surface properties and blocking of the activity of proteins and the structures used by the bacteria to interact with surfaces.
  9. Wang Y, Wei DQ, Wang JF
    J Chem Inf Model, 2010 May 24;50(5):875-8.
    PMID: 20443585 DOI: 10.1021/ci900458u
    T1 lipase is isolated from the palm Geobacillus zalihae strain T1 in Malaysia, functioning as a secreted protein responsible for the catalyzing hydrolysis of long-chain triglycerides into fatty acids and glycerol at high temperatures. In the current study, using 30 ns molecular dynamics simulations at different temperatures, an aqueous activation was detected for T1 lipase. This aqueous activation in T1 lipase was mainly caused by a double-flap movement mechanism. The double flaps were constituted by the hydrophobic helices 6 and 9. Helix 6 employed two major components with the hydrophilic part at the surface and the hydrophobic part inside. In the aqueous solution, the hydrophobic part could provide enough power for helix 6 to move away, driving the protein into an open configuration and exposing the catalytic triad. Our findings could provide structural evidence to support the double-flap movement, revealing the catalytic mechanism for T1 lipase.
  10. Tan M, Aghaei F, Wang Y, Zheng B
    Phys Med Biol, 2017 01 21;62(2):358-376.
    PMID: 27997380 DOI: 10.1088/1361-6560/aa5081
    The purpose of this study is to evaluate a new method to improve performance of computer-aided detection (CAD) schemes of screening mammograms with two approaches. In the first approach, we developed a new case based CAD scheme using a set of optimally selected global mammographic density, texture, spiculation, and structural similarity features computed from all four full-field digital mammography images of the craniocaudal (CC) and mediolateral oblique (MLO) views by using a modified fast and accurate sequential floating forward selection feature selection algorithm. Selected features were then applied to a 'scoring fusion' artificial neural network classification scheme to produce a final case based risk score. In the second approach, we combined the case based risk score with the conventional lesion based scores of a conventional lesion based CAD scheme using a new adaptive cueing method that is integrated with the case based risk scores. We evaluated our methods using a ten-fold cross-validation scheme on 924 cases (476 cancer and 448 recalled or negative), whereby each case had all four images from the CC and MLO views. The area under the receiver operating characteristic curve was AUC  =  0.793  ±  0.015 and the odds ratio monotonically increased from 1 to 37.21 as CAD-generated case based detection scores increased. Using the new adaptive cueing method, the region based and case based sensitivities of the conventional CAD scheme at a false positive rate of 0.71 per image increased by 2.4% and 0.8%, respectively. The study demonstrated that supplementary information can be derived by computing global mammographic density image features to improve CAD-cueing performance on the suspicious mammographic lesions.
  11. Zhu C, Li Y, Zhang L, Wang Y
    PLoS One, 2020;15(11):e0241618.
    PMID: 33156886 DOI: 10.1371/journal.pone.0241618
    To provide a theoretical basis for sustainable land resource utilization and a reference for areas with similar natural conditions, an evaluation index for land-based ecological security was constructed based on the Driving force-Pressure-State-Impact-Response (DPSIR) model and the improved analytic hierarchy process (IAHP) and entropy methods, and the land-based ecological security status of Xingtai city from 2006 to 2017 was evaluated. Then, the obstacles to land-based ecological security were diagnosed. The results show that the values of the comprehensive evaluation index of land-based ecological security were 0.28-0.66 in the period from 2006 to 2017. The value of the index of land-based ecological security was low in the first seven years and gradually improved in the last five years of the study period. However, the overall situation was grave, and the ecological security conditions were poor. The main obstacles to land-based ecological security were the usage of pesticides, investment in environmental pollution treatments, the degree of machine cultivation, the rate of cultivation and the usage of fertilizer in Xingtai city. Based on the results of the land-based ecological security evaluation and the main obstacles identified in Xingtai city, this paper proposes management strategies and suggestions for improving land-based ecological security in Xingtai city. The specific proposals are as follows: vigorously develop green agriculture, increase investment in environmental pollution control, increase input in science and technology, and strengthen supervision and management of land use.
  12. Wang Y, Chung FF, Lee SM, Dykes GA
    BMC Res Notes, 2013;6:143.
    PMID: 23578062 DOI: 10.1186/1756-0500-6-143
    Tea has been suggested to promote oral health by inhibiting bacterial attachment to the oral cavity. Most studies have focused on prevention of bacterial attachment to hard surfaces such as enamel.
  13. Eamsobhana P, Gan XX, Ma A, Wang Y, Wanachiwanawin D, Yong HS
    J. Helminthol., 2014 Dec;88(4):396-401.
    PMID: 23710755 DOI: 10.1017/S0022149X13000321
    A rapid dot immunogold filtration assay (DIGFA) was adopted for specific immunodiagnosis of human cerebral angiostrongyliasis, using purified 31-kDa glycoprotein specific to Angiostrongylus cantonensis as diagnostic antigen and protein A colloidal gold conjugate as antigen-antibody detector. A total of 59 serum samples were assayed - 11 samples from clinically diagnosed patients with detectable A. cantonensis-specific antibody in immunoblotting; 23 samples from patients with other related parasitic diseases, i.e. gnathostomiasis (n= 8), cysticercosis (n= 5), toxocariasis (n= 2), filariasis (n= 4), paragonimiasis (n= 2) and malaria (n= 2); and 25 samples from normal healthy subjects. The sensitivity and specificity of DIGFA to detect anti-A. cantonensis specific antibodies in serologically confirmed angiostrongyliasis cases, were both 100%. No positive DIGFA was observed in cases with other parasitic diseases, and the healthy control subjects. The 3-min DIGFA is as sensitive and specific as the 3-h immunoblot test in angiostrongyliasis confirmed cases that revealed a 31-kDa reactive band. The gold-based DIGFA is more rapid and easier to perform than the traditional enzyme-linked immunosorbent assay (ELISA). The test utilizing purified A. cantonensis antigen is reliable and reproducible for specific immunodiagnosis of human infection with A. cantonensis - thus can be applied as an additional routine test for clinical diagnostic support. Large-scale sero-epidemiological studies in endemic communities in north-east Thailand are under way to evaluate its usefulness under field conditions.
  14. Wang Y, See J, Phan RC, Oh YH
    PLoS One, 2015;10(5):e0124674.
    PMID: 25993498 DOI: 10.1371/journal.pone.0124674
    Micro-expression recognition is still in the preliminary stage, owing much to the numerous difficulties faced in the development of datasets. Since micro-expression is an important affective clue for clinical diagnosis and deceit analysis, much effort has gone into the creation of these datasets for research purposes. There are currently two publicly available spontaneous micro-expression datasets--SMIC and CASME II, both with baseline results released using the widely used dynamic texture descriptor LBP-TOP for feature extraction. Although LBP-TOP is popular and widely used, it is still not compact enough. In this paper, we draw further inspiration from the concept of LBP-TOP that considers three orthogonal planes by proposing two efficient approaches for feature extraction. The compact robust form described by the proposed LBP-Six Intersection Points (SIP) and a super-compact LBP-Three Mean Orthogonal Planes (MOP) not only preserves the essential patterns, but also reduces the redundancy that affects the discriminality of the encoded features. Through a comprehensive set of experiments, we demonstrate the strengths of our approaches in terms of recognition accuracy and efficiency.
  15. Yap WS, Chan CC, Chan SP, Wang YT
    Respir Med, 2001 Apr;95(4):297-304.
    PMID: 11316113
    When standing height (StndHt) cannot be assessed, arm span (AS) or sitting height (SitHt) has been used as surrogate variables for prediction of StndHt in adult caucasians and blacks. We examined (1) the relationship between StndHt, AS and SitHt among adult Chinese, Malays and Indians; and (2) whether anthropometry could explain the ethnic differences in lung volumes (as StndHt-adjusted lung volumes are known to differ significantly: Chinese > Malays > Indians). We recruited 1250 consecutive outpatients aged 20-90 years. Prediction equations of StndHt (with AS, SitHt, weight, age as predictors) for each subgroup of race and sex were formulated with multiple linear regressions. Equations with both AS and SitHt as predictors had the best goodness of fit (SEE = 2.37-2.85 cm, adjusted R2 = 0.67-0.87), as compared to equations with either AS (SEE = 3.00-3.91 cm, adjusted R2 = 0.58-0.80) or SitHt alone (SEE = 3.48-4.00 cm, adjusted R2 = 0.45-0.76). GLM general factorial analyses found that age- and weight-adjusted SitHt-to-StndHt ratios differed significantly among Chinese (0.539), Malays (0.529) and Indians (0.518). This paralleled the ethnic differences in lung volumes. The equations with both AS and SitHt as predictors provide the most accurate estimate of StndHt. Ethnic differences in upper body segment length may explain in part the lung volume differences.
    Study site: Respiratory clinic, Tan Tock Seng Hospital, Singapore
  16. Chia SE, Wang YT, Chan OY, Poh SC
    Ann Acad Med Singap, 1993 Nov;22(6):878-84.
    PMID: 8129348
    Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), peak expiratory flow rate (PEFR), single-breath diffusion capacity measurements (effective alveolar volume (VA), carbon monoxide transfer factor (DLCO) and transfer coefficient (KCO)) were determined in 452 healthy Singaporean adults (277 males and 175 females) aged 20-70 years. The ratio of Chinese, Malay and Indian subjects was 5:2:3 in both sexes. Age, height and weight in the males were all significantly correlated with FEV1, FVC, DLCO, VA and PEFR. However, for females, only age and height were significantly correlated with the studied lung function parameters. Significant ethnic differences were observed for most of the pulmonary functions (except KCO and PEFR) among the Chinese, Malays and Indians for both males and females. The predicted FEV1 and FVC values (specific age and height) for both sexes were highest among the Chinese followed by the Malays than Indians, in that order. Regression equations, with age and height as independent variables, were derived for males and females in each ethnic group to predict normal pulmonary function for the Singapore Chinese, Malay and Indian populations. The predicted values of various pulmonary function measurements obtained from these regression equations for subjects of specified age (30 years) and height (165 cm for men, 155 cm for women) were compared with those reported in other studies. Differences were observed among the different races.
  17. Johan A, Chan CC, Chia HP, Chan OY, Wang YT
    Eur Respir J, 1997 Dec;10(12):2825-8.
    PMID: 9493668
    Maximal static inspiratory and expiratory mouth pressures (PI,max and PE,max, respectively) enable the noninvasive measurement of global respiratory muscle strength. The aim of this study was primarily to obtain normal values of PI,max and PE,max for adult Chinese, Malays and Indians and, secondarily, to study their effect on lung volumes in these subjects. Four hundred and fifty two healthy subjects (221 Chinese, 111 Malays, 120 Indians) were recruited. Measurements of PI,max from residual volume (RV), PE,max from total lung capacity (TLC) and forced vital capacity (FVC) were obtained in the seated position. There were significant ethnic differences in PI,max and PE,max measurements obtained in males, and FVC measurements in both males and females. Chinese males had higher PI,max values (mean (+/-SD) 88.7+/-32.5 cmH2O) and higher PE,max values (113.4+/-41.5) than Malay males (PI,max 74.0+/-22.7 cmH2O, PE,max 94.7+/-23.4 cmH2O). Chinese males had higher PE,max than Indian males (PI,max = 83.7+/-30.0 cmH2O, PE,max 98.4+/-29.2 cmH2O). There were no significant differences among Chinese females (PI,max 53.6+/-2.3 cmH2O, PE,max 68.3+/-24.0 cmH2O), Malay females (PI,max 50.7+/-18.3 cmH2O, PE,max 63.6+/-21.6 cmH2O) and Indian females (PI,max 50.0+/-15.2 cmH2O, PE,max 60.7+/-20.4 cmH2O). In both sexes, the Chinese had a higher FVC compared with Malays and Indians. After adjusting for age, height and weight, race was still a determinant for PE,max in males, and FVC in both sexes. The FVC only correlated weakly with PI,max and PE,max in both sexes. Ethnic differences in respiratory muscle strength, and lung volumes, occur among Asians. However, respiratory muscle strength does not explain the differences in lung volumes in healthy Asian subjects.
  18. Qi J, Zhang H, Wang Y, Mani MP, Jaganathan SK
    Int J Nanomedicine, 2018;13:2777-2788.
    PMID: 29785105 DOI: 10.2147/IJN.S151242
    Introduction: Currently, the design of extracellular matrix (ECM) with nanoscale properties in bone tissue engineering is challenging. For bone tissue engineering, the ECM must have certain properties such as being nontoxic, highly porous, and should not cause foreign body reactions.

    Materials and methods: In this study, the hybrid scaffold based on polyvinyl alcohol (PVA) blended with metallocene polyethylene (mPE) and plectranthus amboinicus (PA) was fabricated for bone tissue engineering via electrospinning. The fabricated hybrid nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform and infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), contact angle measurement, and atomic force microscopy (AFM). Furthermore, activated partial thromboplastin time (APTT), prothrombin time (PT), and hemolytic assays were used to investigate the blood compatibility of the prepared hybrid nanocomposites.

    Results: The prepared hybrid nanocomposites showed reduced fiber diameter (238±45 nm) and also increased porosity (87%) with decreased pore diameter (340±86 nm) compared with pure PVA. The interactions between PVA, mPE, and PA were identified by the formation of the additional peaks as revealed in FTIR. Furthermore, the prepared hybrid nanocomposites showed a decreased contact angle of 51°±1.32° indicating a hydrophilic nature and exhibited lower thermal stability compared to pristine PVA. Moreover, the mechanical results revealed that the electrospun scaffold showed an improved tensile strength of 3.55±0.29 MPa compared with the pristine PVA (1.8±0.52 MPa). The prepared hybrid nanocomposites showed delayed blood clotting as noted in APTT and PT assays indicating better blood compatibility. Moreover, the hemolysis assay revealed that the hybrid nanocomposites exhibited a low hemolytic index of 0.6% compared with pure PVA, which was 1.6% suggesting the safety of the developed nanocomposite to red blood cells (RBCs).

    Conclusion: The prepared nanocomposites exhibited better physico-chemical properties, sufficient porosity, mechanical strength, and blood compatibility, which favors it as a valuable candidate in bone tissue engineering for repairing the bone defects.

  19. Xia N, Deng D, Wang Y, Fang C, Li SJ
    Int J Nanomedicine, 2018;13:2521-2530.
    PMID: 29731627 DOI: 10.2147/IJN.S154046
    Background: Prostate-specific antigen (PSA), a serine protease, is a biomarker for preoperative diagnosis and screening of prostate cancer and monitoring of its posttreatment.

    Methods: In this work, we reported a colorimetric method for clinical detection of PSA using gold nanoparticles (AuNPs) as the reporters. The method is based on ascorbic acid (AA)-induced in situ formation of AuNPs and Cu2+-catalyzed oxidation of AA. Specifically, HAuCl4 can be reduced into AuNPs by AA; Cu2+ ion can catalyze the oxidation of AA by O2 to inhibit the formation of AuNPs. In the presence of the PSA-specific peptide (DAHSSKLQLAPP)-modified gold-coated magnetic microbeads (MMBs; denoted as DAHSSKLQLAPP-MMBs), complexation of Cu2+ by the MMBs through the DAH-Cu2+ interaction depressed the catalyzed oxidation of AA and thus allowed for the formation of red AuNPs. However, once the peptide immobilized on the MMB surface was cleaved by PSA, the DAHSSKLQ segment would be released. The resultant LAPP fragment remaining on the MMB surface could not sequestrate Cu2+ to depress its catalytic activity toward AA oxidation. Consequently, no or less AuNPs were generated.

    Results: The linear range for PSA detection was found to be 0~0.8 ng/mL with a detection limit of 0.02 ng/mL. Because of the separation of cleavage step and measurement step, the interference of matrix components in biological samples was avoided.

    Conclusion: The high extinction coefficient of AuNPs facilitates the colorimetric analysis of PSA in serum samples. This work is helpful for designing of other protease biosensors by matching specific peptide substrates.

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