Displaying publications 1 - 20 of 203 in total

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  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. 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.
  3. 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.
  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. 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.
  6. 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.
  7. 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.
  8. 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.
  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. 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.
  11. Abdullah B, Chuen CS, Husain S, Snidvongs K, Wang Y
    PMID: 30061792 DOI: 10.1186/s12901-018-0060-5
    Background: The orbital floor is considered as an important intraoperative reference point in endoscopic sinonasal surgery. The aim of this review is to evaluate its reliability and usefulness as a surgical landmark in endoscopic endonasal surgery.

    Methods: A literature search was performed on electronic databases, namely PUBMED. The following keywords were used either individually or in combination: orbital floor; maxillary sinus roof; endoscopic skull base surgery; endoscopic sinus surgery. Studies that used orbital floor as a landmark for endoscopic endonasal surgery were included in the analysis. In addition, relevant articles were identified from the references of articles that had been retrieved. The search was conducted over a period of 6 months between 1st June 2017 and 16th December 2017.

    Results: One thousand seven hundred forty-three articles were retrieved from the electronic databases. Only 5 articles that met the review criteria were selected. Five studies of the orbital floor (or the maxillary sinus roof) were reviewed, one was a cadaveric study while another 4 were computed tomographic study of the paranasal sinuses. All studies were of level III evidence and consists of a total number of 948 nostrils. All studies showed the orbital floor was below the anterior skull base irrespective of the populations. The orbital floor serves as a guide for safe entry into posterior ethmoids and sphenoid sinus.

    Conclusions: The orbital floor is a reliable and useful surgical landmark in endoscopic endonasal surgery. In revision cases or advanced disease, the normal landmarks can be distorted or absent and the orbital floor serves as a reference point for surgeons to avoid any unintentional injury to the skull base, the internal carotid artery and other critical structures.

  12. Liang H, Qin X, Tan CP, Li D, Wang Y
    J. Agric. Food Chem., 2018 Nov 21;66(46):12361-12367.
    PMID: 30394748 DOI: 10.1021/acs.jafc.8b04804
    Docosahexaenoyl and eicosapentaenoyl ethanolamides (DHEA and EPEA) have physiological functions, including immunomodulation, brain development, and anti-inflammation, but their efficient production is still unresolved. In this study, choline-chloride-based natural deep eutectic solvents are used as media to improve the production of DHEA and EPEA. The water content showed a key effect on the reactant conversion. Adding water to choline chloride-glucose (CG, molar ratio of 5:2) led to a significant increase (13.03% for EPEA and 27.95% for DHEA) in the yields after 1 h. The high yields of EPEA (96.84%) and DHEA (90.06%) were obtained under the optimized conditions [fish oil ethyl esters/ethanolamine molar ratio of 1:2, temperature of 60 °C, 1 h, enzyme loading of 2195 units, and CG containing 8.50% water of 43.30% (w/w, relative to total reactants)]. The products could be easily separated using centrifugation. In summary, the research has the potential to produce fatty acyl ethanolamides.
  13. Lian W, Wang W, Tan CP, Wang J, Wang Y
    Bioprocess Biosyst Eng, 2019 Feb;42(2):321-329.
    PMID: 30421172 DOI: 10.1007/s00449-018-2036-7
    LML-type structured lipids are one type of medium- and long-chain triacylglycerols. LML was synthesized using immobilized Talaromyces thermophilus lipase (TTL)-catalyzed interesterification of tricaprylin and ethyl linoleate. The resin AB-8 was chosen, and the lipase/support ratio was determined to be 60 mg/g. Subsequently, the immobilized TTL with strict sn-1,3 regiospecificity was applied to synthesize LML. Under the optimized conditions (60 °C, reaction time 6 h, enzyme loading of 6% of the total weight of substrates, substrate of molar ratio of ethyl linoleate to tricaprylin of 6:1), Triacylglycerols with two long- and one medium-chain FAs (DL-TAG) content as high as 52.86 mol% was obtained. Scale-up reaction further verified the industrial potential of the established process. The final product contained 85.24 mol% DL-TAG of which 97 mol% was LML after purification. The final product obtained with the high LML content would have substantial potential to be used as functional oils.
  14. Abdullah B, Lim EH, Husain S, Snidvongs K, Wang Y
    Surg Radiol Anat, 2019 May;41(5):491-499.
    PMID: 30542930 DOI: 10.1007/s00276-018-2165-3
    PURPOSE: Anterior ethmoidal artery (AEA) is at risk of injury in endoscopic sinus surgery due to its location. The aim of this review was to assess the anatomical variations of AEA and their significance.

    METHODS: A literature search was performed on PUBMED, SCOPUS AND EMBASE. The following keywords were used: ethmoidal artery; anterior ethmoidal artery; anterior ethmoidal canal; ethmoid sinus; ethmoid roof; skull base. The search was conducted over a period of 6 months between October 2016 and April 2017.

    RESULTS: 105 articles were retrieved. 76 articles which were either case reports or unrelated topics were excluded. Out of the 29 full text articles retrieved, 16 articles were selected; 3 were cadaveric dissection, 5 combined cadaveric dissection and computed tomography (CT) and the rest were of CT studies. All studies were of level III evidence and a total of 1985 arteries were studied. Its position at the skull base was influenced by the presence of supraorbital ethmoid cell (SOEC) and length of the lateral lamella of cribriform plate (LLCP). Inter population morphological variations contribute to the anatomical variations.

    CONCLUSIONS: The average diameter of AEA was 0.80 mm and the intranasal length was 5.82 mm. 79.2% was found between the second and third lamellae, 12.0% in the third lamella, 6% posterior to third lamella and 1.2% in the second lamella. Extra precaution should be taken in the presence of a well-pneumatized SOEC and a long LLCP as AEA tends to run freely below skull base.

  15. Chen Z, Ding G, Wang Y, Xu J, Lin Z
    J. Genet., 2018 Nov 14;97(5):e147-e151.
    PMID: 30574879
    The tiger frog Hoplobatrachus rugulosus (Wiegmann 1834) is a large robust dicroglossid frog widely distributed in southern China, Malaysia, Myanmar, Vietnam and Thailand. The escaped bred tiger frog introduced from Thailand hybridized with Chinese native population may have affected the genetic diversity of local Chinese tiger frogs. However, previous microsatellite loci of this species do not offer enough information to construct the genetic map. Here, we reported 33 new microsatellite loci from transcriptome sequencing for H. rugulosus. Alleles ranged between 1 and 10 per locus and only one locus (HRT001) was monomorphic. The polymorphic information content, observed and expected heterozygosity were 0-0.794, 0-0.969 and 0-0.831, respectively. None of the loci was observed in linkage disequilibrium and two loci (HRT023 and HRT068) deviated from Hardy-Weinberg equilibrium after Bonferroni correction for multiple tests. These transcriptome-derived microsatellite markers will be usedto study the genetic divergence and construct the genetic map in H. rugulosus.
  16. Qian L, Su W, Wang Y, Dang M, Zhang W, Wang C
    Artif Cells Nanomed Biotechnol, 2019 Dec;47(1):1173-1180.
    PMID: 30942109 DOI: 10.1080/21691401.2018.1549064
    Cervical cancer is the third most common highest mortality in women worldwide. The use of standard chemotherapeutic drugs against cervical cancer patients received several side effects. Therefore, we focused phytoconsituents-mediated synthesis of gold nanoparticles (AuNPs) considered as greatest attention in the treatment of cervical cancer. In this present study, we reported that green synthesis of AuNPs by using with Alternanthera Sessilis aqueous extract. Synthesis of AuNPs were characterized by UV visible spectroscopy, energy dispersive X-ray (EDX), selected area diffraction pattern (SAED), Fourier transform infrared spectroscopy (FTIR), high-resolution transmission electron microscopy (HR-TEM) and atomic force microscope. Synthesized AuNPs confirmed by the UV absorption maximum at 535 and crystal structure of gold AuNPs was further confirmed by EDX and SAED. TEM and atomic force microscopy images show the size and morphological distribution of nanoparticles. FTIR analysis was confirmed the hydroxyl groups, amine and alkaline groups of biomolecules are present in the AuNPs. Moreover, AuNPs induce cytotoxicity in cervical cancer cells and also induce apoptosis through modulating intrinsic apoptotic mechanisms in cervical cancer cells. This green synthesis of AuNPs from Alternanthera sessilis approach was easy, large scaled up and eco-friendly.
  17. Hajli MN, Shanmugam M, Hajli A, Khani AH, Wang Y
    Inform Health Soc Care, 2015 Dec;40(4):334-344.
    PMID: 25068990 DOI: 10.3109/17538157.2014.924950
    The emergence of Web 2.0 technologies has already been influential in many industries, and Web 2.0 applications are now beginning to have an impact on health care. These new technologies offer a promising approach for shaping the future of modern health care, with the potential for opening up new opportunities for the health care industry as it struggles to deal with challenges including the need to cut costs, the increasing demand for health services and the increasing cost of medical technology. Social media such as social networking sites are attracting more individuals to online health communities, contributing to an increase in the productivity of modern health care and reducing transaction costs. This study therefore examines the potential effect of social technologies, particularly social media, on health care development by adopting a social support/transaction cost perspective. Viewed through the lens of Information Systems, social support and transaction cost theories indicate that social media, particularly online health communities, positively support health care development. The results show that individuals join online health communities to share and receive social support, and these social interactions provide both informational and emotional support.
  18. Saniasiaya J, Abdullah B, Husain S, Wang Y, Wan Mohammad Z
    Am J Rhinol Allergy, 2017 Sep 01;31(5):328-333.
    PMID: 28859711 DOI: 10.2500/ajra.2017.31.4464
    BACKGROUND: Epiphora secondary to nasolacrimal duct obstruction is common in the pediatric age group. The mainstay treatment among these young patients has been conservative. Once epiphora becomes recalcitrant, however, an external or an endonasal approach is considered.

    OBJECTIVE: Endoscopic dacryocystorhinostomy (EDCR) entails creating an opening from the lacrimal sac directly into the nasal cavity to counteract nasolacrimal duct obstruction. We reviewed the literature to determine the effectiveness and the safety of primary EDCR to treat pediatric nasolacrimal duct obstruction.

    METHOD: A literature search was conducted by using a number of medical literature data bases for the period from 1995 to 2016. The following search words were used either individually or in combination: epiphora, nasolacrimal duct obstruction, endoscopic dacryocystorhinostomy, powered endoscopic dacryocystorhinostomy, laser-assisted endoscopic dacryocystorhinostomy, children, congenital, acquired, presaccal obstruction, and postsaccal obstruction. In addition, a few articles were identified based on the experience and information provided by the senior authors (B.A., S.H., D.Y.W.). The search was conducted over a 1-month period (January 2017). Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and the Cochrane Handbook for Systematic Reviews of Interventions were followed when possible.

    RESULTS: Only 10 original clinical research articles were selected based on our objectives and selection criteria. All the studies were at level of evidence III: nonrandomized and noncomparative prospective or retrospective case series. Altogether, 313 patients with ages that ranged from 4 months to 18 years were enrolled. A total of 352 EDCRs were performed that were either single sided (n = 313) or bilateral (n = 39). The most common causes of the obstruction were classified as congenital, followed by idiopathic, and then acquired. A meta-analysis was not performed because of the heterogeneity of the patient groups and variability of the methods used to measure outcomes.

    CONCLUSION: Analysis of the results indicated that EDCR was an effective, safe therapeutic approach to treating nasolacrimal duct obstruction in pediatric patients. It should be considered as an alternative procedure to external dacryocystorhinostomy after a failed conservative treatment.

  19. Li Y, Ren S, Yan B, Zainal Abidin IM, Wang Y
    Sensors (Basel), 2017 Jul 31;17(8).
    PMID: 28758985 DOI: 10.3390/s17081747
    A corrosive environment leaves in-service conductive structures prone to subsurface corrosion which poses a severe threat to the structural integrity. It is indispensable to detect and quantitatively evaluate subsurface corrosion via non-destructive evaluation techniques. Although the gradient-field pulsed eddy current technique (GPEC) has been found to be superior in the evaluation of corrosion in conductors, it suffers from a technical drawback resulting from the non-uniform field excited by the conventional pancake coil. In light of this, a new GPEC probe with uniform field excitation for the imaging of subsurface corrosion is proposed in this paper. The excited uniform field makes the GPEC signal correspond only to the field perturbation due to the presence of subsurface corrosion, which benefits the corrosion profiling and sizing. A 3D analytical model of GPEC is established to analyze the characteristics of the uniform field induced within a conductor. Following this, experiments regarding the imaging of subsurface corrosion via GPEC have been carried out. It has been found from the results that the proposed GPEC probe with uniform field excitation not only applies to the imaging of subsurface corrosion in conductive structures, but provides high-sensitivity imaging results regarding the corrosion profile and opening size.
  20. 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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