Evaluation of click chemistry microarrays for immunosensing of alpha-fetoprotein (AFP)

The level of cancer biomarkers in cells, tissues or body fluids can be used for the prediction of the presence of cancer or can even indicate the stage of the disease. Alpha-fetoprotein (AFP) is the most commonly used biomarker for early screening and diagnosis of hepatocellular carcinoma (HCC). Here, a combination of three techniques (click chemistry, the biotin–streptavidin–biotin sandwich strategy and the use of antigen–antibody interactions) were combined to implement a sensitive fluorescent immunosensor for AFP detection. Three types of functionalized glasses (dibenzocyclooctyne- (DBCO-), thiol- and epoxy-terminated surfaces) were biotinylated by employing the respective adequate click chemistry counterparts (biotin–thiol or biotin–azide for the first class, biotin–maleimide or biotin–DBCO for the second class and biotin–amine or biotin–thiol for the third class). The anti-AFP antibody was immobilized on the surfaces via a biotin–streptavidin–biotin sandwich technique. To evaluate the sensing performance of the differently prepared surfaces, fluorescently labeled AFP was spotted onto them via microchannel cantilever spotting (µCS). Based on the fluorescence measurements, the optimal microarray design was found and its sensitivity was determined

Fluorescence Imaging Study of Film Coating Structure and Composition Effects on DNA Hybridization

Hybridization of surface‐bound DNA with complementary strands is the basis of many biotechnological applications. Herein, the structure of interfacial coatings between substrate and bound DNA is a crucial element for hybridization behavior. Herein, three reactive surfaces for constructing DNA‐sensing platforms, namely, plain gold films on silicon, poly(bisphenolA‐co‐epichlorohydrin) (PBAG) surfaces with a brush‐like bilayer structure, and dibenzocyclooctyne monolayers (both on glass), are compared. Fluorescence imaging is employed to survey the effect of coating structure and conformation on hybridization performance. To better understand the interfacial structural properties and chemistry of the coated films, atomic force microscopy, water contact angle measurements, and X‐ray photoelectron spectroscopy are employed to characterize the surface morphology. DNA probe microarrays are created on the different platforms via microchannel cantilever spotting, and their performance for hybridizing with the DNA counterparts is assessed. While all three platforms work reliable for DNA detection, a protein‐binding assay reveals that PBAG surfaces offer the highest hybridization efficiency among these approaches. The results of the present work have significant implications for comprehension of the interactions between the DNA hybridization efficiency and the physico‐chemical properties of surface coatings and can inform the fabrication of DNA sensors

Verification Techniques for Cache Coherence Protocols

In this article we present a comprehensive survey of various approaches for the verification of cache coherence protocols based on state enumeration, (symbolic) model checking, and symbolic state models. Since these techniques search the state space of the protocol exhaustively, the amount of memory required to manipulate the state information and the verification time grow very fast with the number of processors and the complexity of the protocol mechanisms. To be successful for systems of arbitrary complexity, a verification technique must solve this so-called state space explosion problem. The emphasis of our discussion is on the underlying theory in each method of handling the state space explosion problem, and formulating and checking the safety properties (e.g., data consistency) and the liveness properties (absence of deadlock and livelock). We compare the efficiency and discuss the limitations of each technique in terms of memory and computation time. Also, we discuss issues of generality, applicability, automaticity, and amenity for existing tools in each class of methods. No method is truly superior because each method has its own strengths and weaknesses. Finally, refinements that can further reduce the verification time and/or the memory requirement are also discussed

Fluorescence Imaging Study of Film Coating Structure and Composition Effects on DNA Hybridization

Hybridization of surface‐bound DNA with complementary strands is the basis of many biotechnological applications. Herein, the structure of interfacial coatings between substrate and bound DNA is a crucial element for hybridization behavior. Herein, three reactive surfaces for constructing DNA‐sensing platforms, namely, plain gold films on silicon, poly(bisphenolA‐co‐epichlorohydrin) (PBAG) surfaces with a brush‐like bilayer structure, and dibenzocyclooctyne monolayers (both on glass), are compared. Fluorescence imaging is employed to survey the effect of coating structure and conformation on hybridization performance. To better understand the interfacial structural properties and chemistry of the coated films, atomic force microscopy, water contact angle measurements, and X‐ray photoelectron spectroscopy are employed to characterize the surface morphology. DNA probe microarrays are created on the different platforms via microchannel cantilever spotting, and their performance for hybridizing with the DNA counterparts is assessed. While all three platforms work reliable for DNA detection, a protein‐binding assay reveals that PBAG surfaces offer the highest hybridization efficiency among these approaches. The results of the present work have significant implications for comprehension of the interactions between the DNA hybridization efficiency and the physico‐chemical properties of surface coatings and can inform the fabrication of DNA sensors