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580 KiB

Open AccessArticle

Interfacial Recognition of Acetylcholine by an Amphiphilic p-Sulfonatocalix[8]arene Derivative Incorporated into Dimyristoyl Phosphatidylcholine Vesicles

by Takashi Jin, Fumihiko Fujii and Yasuhiro Ooi

Sensors 2008, 8(10), 6777-6790; https://doi.org/10.3390/s8106777 - 29 Oct 2008

Cited by 18 | Viewed by 12793

Abstract

Dodecyl ether derivatives 1-3 of p-sulfonatocalix[n]arene were incorporated into dimyristoyl phosphatidylcholine (DMPC) vesicles, and their binding abilities for acetylcholine (ACh) were examined by using steady-state fluorescence/fluorescence anisotropy and fluorescence correlation spectroscopy (FCS). For the detection of ACh binding to the DMPC vesicles containing [...] Read more.

Dodecyl ether derivatives 1-3 of p-sulfonatocalix[n]arene were incorporated into dimyristoyl phosphatidylcholine (DMPC) vesicles, and their binding abilities for acetylcholine (ACh) were examined by using steady-state fluorescence/fluorescence anisotropy and fluorescence correlation spectroscopy (FCS). For the detection of ACh binding to the DMPC vesicles containing 5 mol % of 1-3, competitive fluorophore displacement experiments were performed, where rhodamine 6G (Rh6G) was used as a fluorescent guest. The addition of Rh6G to the DMPC vesicles containing 3 resulted in a decrease in the fluorescence intensity of Rh6G with an increase of its fluorescence anisotropy, indicating that Rh6G binds to the DMPC-3 vesicles. In the case of DMPC-1 and DMPC-2 vesicles, significant changes in the fluorescence spectra of Rh6G were not observed. When ACh was added to the DMPC-3 vesicles in the presence of Rh6G ([3]/[Rh6G]=100), the fluorescence intensity of Rh6G increased with a decrease in its fluorescence anisotropy. From the analysis of fluorescence titration data, the association constants were determined to be 7.1×10⁵ M^-1 for Rh6G-3 complex and 1.1×10² M^-1 for ACh-3 complex at the DMPC-3 vesicles. To get a direct evidence for the binding of Rh6G and its displacement by ACh at the DMPC-3 vesicles, diffusion times of the Rh6G were measured by using FCS. Binding selectivity of the DMPC-3 vesicles for ACh, choline, GABA, L-aspartic acid, L-glutamic acid, L-arginine, L-lysine, L-histamine and ammonium chloride was also evaluated using FCS. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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435 KiB

Open AccessArticle

Molecularly Imprinted Polymers: Thermodynamic and Kinetic Considerations on the Specific Sorption and Molecular Recognition

by Songjun Li, Xing Huang, Mingxia Zheng, Wuke Li and Kejun Tong

Sensors 2008, 8(4), 2854-2864; https://doi.org/10.3390/s8042854 - 23 Apr 2008

Cited by 31 | Viewed by 12043

Abstract

This article presents a work aiming at thermodynamically and kinetically interpreting the specific sorption and recognition by a molecularly imprinted polymer. Using Boc-L-Phe-OH as a template, the imprinted material was prepared. The result indicates that the prepared polymer can well discriminate the imprint [...] Read more.

This article presents a work aiming at thermodynamically and kinetically interpreting the specific sorption and recognition by a molecularly imprinted polymer. Using Boc-L-Phe-OH as a template, the imprinted material was prepared. The result indicates that the prepared polymer can well discriminate the imprint species from its analogue (Boc-D-Phe-OH), so as to adsorb more for the former but less for the latter. Kinetic analysis indicates that this specific sorption, in nature, can be a result of a preferential promotion. The imprint within the polymer causes a larger adsorption rate for the template than for the analogue. Thermodynamic study also implies that the molecular induction from the specific imprint to the template is larger than to the analogue, which thus makes the polymer capable of preferentially alluring the template to bind. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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127 KiB

Open AccessCommunication

A Fluorescent Sensor for Dinitrobenzoic Acid Based on a Cyanuric Acid and Xanthene Skeleton

by Francisco M. Muñiz, Luis Simón, Silvia Sáez, César Raposo, Victoria Alcázar and Joaquín R. Morán

Sensors 2008, 8(3), 1637-1644; https://doi.org/10.3390/s8031637 - 11 Mar 2008

Cited by 7 | Viewed by 10409

Abstract

A new fluorescent sensor based on a dimethylxanthene skeleton has beensynthesized. Because of its oxyanion hole structure, this receptor includes a suitablecavity for the association of carboxylic acids. The receptor’s fluorescence is quenchedupon addition of dinitrobenzoic acid. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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858 KiB

Open AccessArticle

Naked-eye and Selective Detection of Mercury (II) Ions in Mixed Aqueous Media Using a Cellulose-based Support

by César Díez-Gil, Antonio Caballero, Imma Ratera, Alberto Tárraga, Pedro Molina and Jaume Veciana

Sensors 2007, 7(12), 3481-3488; https://doi.org/10.3390/s7123481 - 21 Dec 2007

Cited by 50 | Viewed by 11090

Abstract

A test paper for high-selectivity detecting Hg²⁺ ions in mixed acetonitrile-watersolutions has been achieved using a bis(ferrocenyl) azine, as chromogenic chemosensormolecule, and a solid cellulose fibre, as a substrate. Depending on the amount of mercuryions in contact with the detecting molecule a [...] Read more.

A test paper for high-selectivity detecting Hg²⁺ ions in mixed acetonitrile-watersolutions has been achieved using a bis(ferrocenyl) azine, as chromogenic chemosensormolecule, and a solid cellulose fibre, as a substrate. Depending on the amount of mercuryions in contact with the detecting molecule a spectacular color change in the celluloseindicator is produced, being possible to determine the concentration of Hg²⁺ ions either bynaked eye or spectroscopically. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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Review

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1172 KiB

Open AccessReview

Imprinting of Molecular Recognition Sites on Nanostructures and Its Applications in Chemosensors

by Guijian Guan, Bianhua Liu, Zhenyang Wang and Zhongping Zhang

Sensors 2008, 8(12), 8291-8320; https://doi.org/10.3390/s8128291 - 15 Dec 2008

Cited by 178 | Viewed by 17883

Abstract

Biological receptors including enzymes, antibodies and active proteins have been widely used as the detection platform in a variety of chemo/biosensors and bioassays. However, the use of artificial host materials in chemical/biological detections has become increasingly attractive, because the synthetic recognition systems such [...] Read more.

Biological receptors including enzymes, antibodies and active proteins have been widely used as the detection platform in a variety of chemo/biosensors and bioassays. However, the use of artificial host materials in chemical/biological detections has become increasingly attractive, because the synthetic recognition systems such as molecularly imprinted polymers (MIPs) usually have lower costs, higher physical/chemical stability, easier preparation and better engineering possibility than biological receptors. Molecular imprinting is one of the most efficient strategies to offer a synthetic route to artificial recognition systems by a template polymerization technique, and has attracted considerable efforts due to its importance in separation, chemo/biosensors, catalysis and biomedicine. Despite the fact that MIPs have molecular recognition ability similar to that of biological receptors, traditional bulky MIP materials usually exhibit a low binding capacity and slow binding kinetics to the target species. Moreover, the MIP materials lack the signal-output response to analyte binding events when used as recognition elements in chemo/biosensors or bioassays. Recently, various explorations have demonstrated that molecular imprinting nanotechniques may provide a potential solution to these difficulties. Many successful examples of the development of MIP-based sensors have also been reported during the past several decades. This review will begin with a brief introduction to the principle of molecular imprinting nanotechnology, and then mainly summarize various synthesis methodologies and recognition properties of MIP nanomaterials and their applications in MIP-based chemosensors. Finally, the future perspectives and efforts in MIP nanomaterials and MIP-based sensors are given. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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944 KiB

Open AccessReview

Recent Progress in Nucleic Acid Aptamer-Based Biosensors and Bioassays

by Wendy Mok and Yingfu Li

Sensors 2008, 8(11), 7050-7084; https://doi.org/10.3390/s8117050 - 7 Nov 2008

Cited by 127 | Viewed by 23456

Abstract

As the key constituents of the genetic code, the importance of nucleic acids to life has long been appreciated. Despite being composed of only four structurally similar nucleotides, single-stranded nucleic acids, as in single-stranded DNAs and RNAs, can fold into distinct three-dimensional shapes [...] Read more.

As the key constituents of the genetic code, the importance of nucleic acids to life has long been appreciated. Despite being composed of only four structurally similar nucleotides, single-stranded nucleic acids, as in single-stranded DNAs and RNAs, can fold into distinct three-dimensional shapes due to specific intramolecular interactions and carry out functions beyond serving as templates for protein synthesis. These functional nucleic acids (FNAs) can catalyze chemical reactions, regulate gene expression, and recognize target molecules. Aptamers, whose name is derived from the Latin word aptus meaning “to fit”, are oligonucleotides that can bind their target ligands with high affinity and specificity. Since aptamers exist in nature but can also be artificially isolated from pools of random nucleic acids through a process called in vitro selection, they can potentially bind a diverse array of compounds. In this review, we will discuss the research that is being done to develop aptamers against various biomolecules, the progress in engineering biosensors by coupling aptamers to signal transducers, and the prospect of employing these sensors for a range of chemical and biological applications. Advances in aptamer technology emphasizes that nucleic acids are not only the fundamental molecules of life, they can also serve as research tools to enhance our understanding of life. The possibility of using aptamer-based tools in drug discovery and the identification of infectious agents can ultimately augment our quality of life. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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1361 KiB

Open AccessReview

Molecular Recognition and Specific Interactions for Biosensing Applications

by Dong Chung Kim and Dae Joon Kang

Sensors 2008, 8(10), 6605-6641; https://doi.org/10.3390/s8106605 - 23 Oct 2008

Cited by 61 | Viewed by 19026

Abstract

Molecular recognition and specific interactions are reliable and versatile routes for site-specific and well-oriented immobilization of functional biomolecules on surfaces. The control of surface properties via the molecular recognition and specific interactions at the nanoscale is a key element for the nanofabrication of [...] Read more.

Molecular recognition and specific interactions are reliable and versatile routes for site-specific and well-oriented immobilization of functional biomolecules on surfaces. The control of surface properties via the molecular recognition and specific interactions at the nanoscale is a key element for the nanofabrication of biosensors with high sensitivity and specificity. This review intends to provide a comprehensive understanding of the molecular recognition- and specific interaction-mediated biosensor fabrication routes that leads to biosensors with well-ordered and controlled structures on both nanopatterned surfaces and nanomaterials. Herein self-assembly of the biomolecules via the molecular recognition and specific interactions on nanoscaled surfaces as well as nanofabrication techniques of the biomolecules for biosensor architecture are discussed. We also describe the detection of molecular recognition- and specific interaction-mediated molecular binding as well as advantages of nanoscale detection. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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1391 KiB

Open AccessReview

Extended Calix[4]arene-Based Receptors for Molecular Recognition and Sensing

by Pik Kwan Lo and Man Shing Wong

Sensors 2008, 8(9), 5313-5335; https://doi.org/10.3390/s8095313 - 1 Sep 2008

Cited by 54 | Viewed by 14328

Abstract

Recent advances in the area of recognition and sensing have shown that artificial receptors derived from extended calix[4]arenes bearing multiple π-conjugated fluorophoric or chromophoric systems have found useful to enhance binding affinity, selectivity and sensitivity for recognition and sensing of a targeted ion [...] Read more.

Recent advances in the area of recognition and sensing have shown that artificial receptors derived from extended calix[4]arenes bearing multiple π-conjugated fluorophoric or chromophoric systems have found useful to enhance binding affinity, selectivity and sensitivity for recognition and sensing of a targeted ion or molecule. A comprehensive review of various π-conjugation-extended calyx[4]arene-based receptors with the highlight on the design and binding characterization for recognition and sensing is presented. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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311 KiB

Open AccessReview

Mesoporous Silicate Materials in Sensing

by Brian J. Melde, Brandy J. Johnson and Paul T. Charles

Sensors 2008, 8(8), 5202-5228; https://doi.org/10.3390/s8085202 - 29 Aug 2008

Cited by 237 | Viewed by 21262

Abstract

Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. [...] Read more.

Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through cocondensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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1815 KiB

Open AccessReview

Chemical Sensors Based on Cyclodextrin Derivatives

by Tomoki Ogoshi and Akira Harada

Sensors 2008, 8(8), 4961-4982; https://doi.org/10.3390/s8084961 - 25 Aug 2008

Cited by 274 | Viewed by 23430

Abstract

This review focuses on chemical sensors based on cyclodextrin (CD) derivatives. This has been a field of classical interest, and is now of current interest for numerous scientists. First, typical chemical sensors using chromophore appended CDs are mentioned. Various “turn-off” and “turn-on” fluorescent [...] Read more.

This review focuses on chemical sensors based on cyclodextrin (CD) derivatives. This has been a field of classical interest, and is now of current interest for numerous scientists. First, typical chemical sensors using chromophore appended CDs are mentioned. Various “turn-off” and “turn-on” fluorescent chemical sensors, in which fluorescence intensity was decreased or increased by complexation with guest molecules, respectively, were synthesized. Dye modified CDs and photoactive metal ion-ligand complex appended CDs, metallocyclodextrins, were also applied for chemical sensors. Furthermore, recent novel approaches to chemical sensing systems using supramolecular structures such as CD dimers, trimers and cooperative binding systems of CDs with the other macrocycle [2]rotaxane and supramolecular polymers consisting of CD units are mentioned. New chemical sensors using hybrids of CDs with p-conjugated polymers, peptides, DNA, nanocarbons and nanoparticles are also described in this review. Full article

(This article belongs to the Special Issue Molecular Recognition and Sensors, Including Molecular Imprinting)

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