Layer-by-layer assembly: from conventional to unconventional methods

Zhang, Xi; Chen, Huan; Zhang, Hongyu

doi:10.1039/b615590a

Cited by 549 publications

(414 citation statements)

References 100 publications

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“…In order to enhance the stability of the deposited molecular layer and shorten the fabrication time, a polyelectrolyte layer-by-layer self-assembly (LBL-SA) method was explored for antibody immobilization. It is well known that the technique of polyelectrolyte multilayers based on electrostatic interaction is a general approach for the fabrication of multicomponent films on solid support in the field of the materials science (Zhang et al, 2007), but this is the first time the method is used in the immunosensor construction for bacteria detection. PEI and PAA are the materials used for deposition of cationic and anionic layers, which are rich in amido groups and carboxyl groups, respectively.…”

Section: Preliminary Exploration For Rapid Constructionmentioning

confidence: 99%

Sensing Escherichia coli O157:H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

Wang

et al. 2008

J. Zhejiang Univ. Sci. B

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By means of the specific immuno-recognition and ultra-sensitive mass detection, a quartz crystal microbalance (QCM) biosensor for Escherichia coli O157:H7 detection was developed in this work. As a suitable surfactant, 16-mercaptohexadecanoic acid (MHDA) was introduced onto the Au surface of QCM, and then self-assembled with N-hydroxysuccinimide (NHS) raster as a reactive intermediate to provide an active interface for the specific antibody immobilization. The binding of target bacteria with the immobilized antibodies decreased the sensor's resonant frequency, and the frequency shift was correlated to the bacterial concentration. The stepwise assembly of the immunosensor was characterized by means of the electrochemical techniques. Using the immersion-dry-immersion procedure, this QCM biosensor could detect 2.0×10 2 colony forming units (CFU)/ml E. coli O157:H7. In order to reduce the fabrication time, a polyelectrolyte layer-by-layer self-assembly (LBL-SA) method was adopted for fast construction. Finally, the reproducibility of this biosensor was discussed.

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Section: Preliminary Exploration For Rapid Constructionmentioning

confidence: 99%

Sensing Escherichia coli O157:H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

Wang

et al. 2008

J. Zhejiang Univ. Sci. B

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“…18−20 Many dynamic bonds, such as hydrogen bonding 21−26 and charge transfer interaction, 27,28 have been used as driving forces for the fabrication of LbL films. 29 Because of the reversible/dynamic nature of these bonds, LbL films linked with dynamic bonds, or dynamic LbL films, will also have a changeable and tunable constitution, just like dynamic polymers. Particularly, these films can undergo a gradual disassembly under proper conditions, 30−33 and therefore may be used for sustained drug release.…”

Section: ■ Introductionmentioning

confidence: 99%

Release of Polyphenolic Drugs from Dynamically Bonded Layer-by-Layer Films

Zhou

Chen

Tian

et al. 2013

ACS Appl. Mater. Interfaces

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Layer-by-layer (LbL) assembled films have been exploited for surface-mediated drug delivery. The drugs loaded in the films were usually released via diffusion or the degradation of one of the film components. Here we demonstrate that drug release can also be achieved by exploiting the dynamic nature of hydrogen-bonded LbL films. The films were fabricated from tannic acid (TA), a model polyphenolic drug, and poly(vinyl pyrrolidone) (PVPON). The driving force for the film buildup is the hydrogen bonding between the two components, which was confirmed by Fourier transform infrared (FTIR) spectra. The film growth is linear, and the growth rate of the film decreases with increasing assembly temperature. Because of the reversible/dynamic nature of hydrogen bonding, when soaked in aqueous solutions, the PVPON/TA films disassemble gradually and thus release TA to the media. The release rate of TA increases with increasing pH and temperature but decreases with increasing ionic strength. Scanning electron microscopy (SEM) studies on the surface morphology of the film during TA release reveal that the film surface becomes smoother and then rougher again because of the dewetting of the film. The released TA can scavenge ABTS +• cation radicals, indicating it retains its antioxidant activity, a major biological activity of polyphenols.

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“…To address these issues, we explored a biocolloid approach pioneered by Lvov, Caruso, and co-workers 24 who used alternate electrostatic layer-by-layer (LbL) adsorption [25][26][27][28] to form active enzyme films of glucose oxidase, horseradish peroxidase, and urease on spherical nanoparticles. The small size of the biocolloids offers increased active surface area and tiny solution volumes to conserve enzyme and also to obtain more product per unit time for subsequent determination of major and minor products.…”

mentioning

confidence: 99%

Enzyme−DNA Biocolloids for DNA Adduct and Reactive Metabolite Detection by Chromatography−Mass Spectrometry

et al. 2008

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Silica microbead bioreactors (0.5 µm diameter) coated with DNA and enzymes were fabricated to measure reactive metabolite and DNA-adduct formation rates relevant to genotoxicity screening. Cytochrome (cyt) P450 2E1, cyt P450 cam , and myoglobin (Mb) were incorporated into thin films with DNA using the electrostatic layer-bylayer (LbL) method. The utility of these biocolloids was demonstrated by oxidation of guaiacol, styrene, and (4-methylnitrosoamino)-1-(3-pyridyl)-1-butanone (NNK). Enzyme turnover rates for formation of reactive metabolites were monitored using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC-MS). Capillary LC-MS/MS was employed to determine DNA nucleobase adducts after catalyzing the reactive metabolite formation with DNAenzyme biocolloids and then using neutral thermal hydrolysis on the biocolloids. Dramatic improvements in surface area to volume ratio over similar films on macroscopic surfaces opens new avenues for genotoxicity screening and enabled the first use of pure cyt P450 enzymes in enzyme-DNA films to produce DNA adducts. The method makes possible identification and formation rate measurements of major and minor DNA adducts as well as the metabolites themselves in <5 min of reaction time using relevant human liver enzymes.Toxicity is often not identified sufficiently early in developing new pharmaceutical, agricultural, personal care, and dietary products. Roughly 30% of drug development failures result from toxicity issues, driving drug costs up significantly. 1-4 Conventional in vitro biological tests such as Ames, chromosome aberration, mouse lymphoma, and Comet assays provide qualitative answers to toxicity questions based on bulk DNA damage but do not give chemical structure or site-specific DNA damage information. 5,6 Animal testing may not relate to human exposure because of metabolic and physiological differences between humans and animal models. 2,4,7 While all these toxicity tests are valuable, we believe that rapid, high-throughput toxicity screening methods for new chemicals that provide chemical structure information about reactive intermediates at early stages of commercial development are important goals to complement conventional microbiological and animal tests.Bioactivation of xenobiotic molecules by metabolic enzymes often results in reactive metabolites that damage biomolecules, including DNA, in a major toxicity pathway. [8][9][10] An example is the metabolism of lipophilic compounds by liver cytochrome (cyt) P450 (or CYP) enzymes creating reactive electrophilic metabolites. 4,11 These electrophiles attack nucleophilic DNA sites, primarily guanines, potentially resulting in genotoxicity. Depending on the adduct site, additional metabolism, and DNA repair processes, covalent DNA adducts can lead to mutations, teratogenesis, and carcinogenesis. 12-14 Thus, nucleobase adducts are key biomarkers for predicting cancer risk in humans and for exposure to toxic chemicals, and sensitive liquid chromatography-mass spectromet...

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Layer-by-layer assembly: from conventional to unconventional methods

Cited by 549 publications

References 100 publications

Sensing Escherichia coli O157:H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

Sensing Escherichia coli O157:H7 via frequency shift through a self-assembled monolayer based QCM immunosensor

Release of Polyphenolic Drugs from Dynamically Bonded Layer-by-Layer Films

Enzyme−DNA Biocolloids for DNA Adduct and Reactive Metabolite Detection by Chromatography−Mass Spectrometry

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