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Nan-Fu Chiu,1,2 Ming-Jung Tai,1 Devi Taufiq Nurrohman,1,3 Ting-Li Lin,1 Ying-Hao Wang,1 Chen-Yu Chen4,5 1Laboratory of Nano-Photonics and Biosensors, Institute of Electro-Optical Engineering, National Taiwan Normal University, Taipei City, Taiwan; 2Department of Life Science, National Taiwan Normal University, Taipei City, Taiwan; 3Department of Electronics Engineering, State Polytechnic of Cilacap, Cilacap, Indonesia; 4Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei City, Taiwan; 5Department of Medicine, Mackay Medical College, Taipei City, TaiwanCorrespondence: Nan-Fu ChiuLaboratory of Nano-Photonics and Biosensors, Institute of Electro-Optical Engineering, National Taiwan Normal University, No. 88, Sec. 4, Ting-Chou Road, Taipei City, 11677, TaiwanTel +886-2-77496722Fax +886-2-86631954Email nfchiu@ntnu.edu.twChen-Yu ChenDepartment of Obstetrics and Gynecology, Mackay Memorial Hospital, No. 92, Sec. 2, Zhongshan N. Road, Taipei City, 10449, TaiwanTel +886-2-25433535Fax +886-2-25433642Email f122481@mmh.org.twBackground: Due to educational, social and economic reasons, more and more women are delaying childbirth. However, advanced maternal age is associated with several adverse pregnancy outcomes, and in particular a high risk of Down’s syndrome (DS). Hence, it is increasingly important to be able to detect fetal Down’s syndrome (FDS).Methods: We developed an effective, highly sensitive, surface plasmon resonance (SPR) biosensor with biochemically amplified responses using carboxyl-molybdenum disulfide (MoS2) film. The use of carboxylic acid as a surface modifier of MoS2 promoted dispersion and formed specific three-dimensional coordination sites. The carboxylic acid immobilized unmodified antibodies in a way that enhanced the bioaffinity of MoS2 and preserved biorecognition properties of the SPR sensor surface. Complete antigen pregnancy-associated plasma protein-A2 (PAPP-A2) conjugated with the carboxyl-MoS2-modified g

Nan-Fu Chiu,1 Ming-Jung Tai,1 Hwai-Ping Wu,1 Ting-Li Lin,1 Chen-Yu Chen2,31Laboratory of Nano-photonics and Biosensors, Institute of Electro-Optical Engineering, National Taiwan Normal University, Taipei 11677, Taiwan; 2Department of Obstetrics and Gynecology, Mackay Memorial Hospital, Taipei City 10449, Taiwan; 3Department of Medicine, Mackay Medical College, Taipei 25245, TaiwanCorrespondence: Nan-Fu ChiuLaboratory of Nano-photonics and Biosensors, Institute of Electro-Optical Engineering, National Taiwan Normal University, No. 88, Sec. 4, Ting-Chou Road, Taipei 11677, TaiwanTel +886 27 734 6722Fax +886 28 663 1954Email nfchiu@ntnu.edu.twBackground: Graphene-like material such as functionalized carboxyl-graphene oxide (carboxyl-GO) can be intelligently tuned to achieve particular properties for biological and chemical sensing applications.Methods: In this study, we propose a method to improve interference of non-specific proteins for use in human plasma assays. The highly specific interactions between molecules are an advantage of carboxyl-GO-based surface plasmon resonance (SPR) immunoassays, and this can be applied to spiked plasma samples with pregnancy-associated plasma protein A2 (PAPPA2).Results: The experiment results showed that carboxyl-GO could be used to modulate the plasmon resonance energy, work function and conductivity properties. In addition, carboxyl groups could be used to enhance the conduction of electrons between carboxyl-GO and Au electrodes due to the excellent conductivity and electron transfer rate. The carboxyl-GO-based SPR chip exhibited high sensitivity based on the electric field amplification effects of the composite dielectric material. Therefore, the surface electric field could be enhanced by electron transfer, thereby greatly improving the sensitivity of the sensing system. Enhanced electric field intensity was generated around the carboxyl-GO of 63.58 V/m, and the measured work function was 4.95 eV. The results showed that the ca

Conflict within mutually beneficial associations is predicted to destabilize relationships, and theoretical and empirical work exploring this has provided significant insight into the dynamics of cooperative interactions. Within mutualistic associations, the expression and regulation of conflict is likely more complex than in intraspecific cooperative relationship, because of the potential presence of: i) multiple genotypes of microbial species associated with individual hosts, ii) multiple species of symbiotic lineages forming cooperative partner pairings, and iii) additional symbiont lineages. Here we explore complexity of conflict expression within the ancient and coevolved mutualistic association between attine ants, their fungal cultivar, and actinomycetous bacteria (Pseudonocardia). Specifically, we examine conflict between the ants and their Pseudonocardia symbionts maintained to derive antibiotics against parasitic microfungi (Escovopsis) infecting the ants' fungus garden. Symbiont assays pairing isolates of Pseudonocardia spp. associated with fungus-growing ants spanning the phylogenetic diversity of the mutualism revealed that antagonism between strains is common. In contrast, antagonism was substantially less common between more closely related bacteria associated with Acromyrmex leaf-cutting ants. In both experiments, the observed variation in antagonism across pairings was primarily due to the inhibitory capabilities and susceptibility of individual strains, but also the phylogenetic relationships between the ant host of the symbionts, as well as the pair-wise genetic distances between strains. The presence of antagonism throughout the phylogenetic diversity of Pseudonocardia symbionts indicates that these reactions likely have shaped the symbiosis from its origin. Antagonism is expected to prevent novel strains from invading colonies, enforcing single-strain rearing within individual ant colonies. While this may align ant-actinomycete interests in the