Analyst Blog

Streptavidin-biotin as example of receptor-ligand binding in TERS

Targeted nanoparticles and Tip-Enhanced Raman spectroscopy (TERS) can be used to investigate biomolecular interactions, suggests a new study published in Analyst.

Hao Wang and Zachary Schultz  at the University of Notre Dame, USA, examine the effect of nanoparticle probe size on detected TERS signal obtained from different functionalised gold nanoparticles, and compare the observed TERS signals from aggregated nanoparticle SERS. TERS is usually employed in the analysis of carbon nanotubes, dye molecules, and semiconductors, but recently it has also been used for detection of molecules in biological samples.
According to the authors, the new methodology suggests a way to enhance TERS signals associated with protein receptors in biological systems that cannot be isolated on a metallic surface.

To read more about this research, please access the link below. This paper will be free to read until March 18^th .

The chemical origin of enhanced signals from tip-enhanced Raman detection of functionalized nanoparticles
Hao Wang and Zachary D. Schultz
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36898J

Visualizing latent fingerprints on stailess steel substrates

Check out our latest hot articles just published in Analyst!

They include a wide variety of topics such as nanospray desorption electrospray ionization for detection of microbial metabolites, near-infrared fluorescent probes for sensing nitroreductase in an aqueous medium, and visualization of latent fingerprint on stainless steel surfaces by electrochemiluminescence. These papers will be free to read until March 25th. Take a look NOW!

Non-destructive enhancement of latent fingerprints on stainless steel surfaces by electrochemiluminescence
Linru Xu ,  Yan Li ,  Yayun He and Bin Su
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN00110E

A novel near-infrared fluorescent probe for selectively sensing nitroreductase (NTR) in an aqueous medium
Youmin Shi ,  Sichun Zhang and Xinrong Zhang
Analyst, 2013, 138, 1952-1955 
DOI: 10.1039/C3AN36807F

Near-infrared fluorescent probe for selectively sensing nitroreductase in an aqueous medium

Label-free selective impedimetric detection of Cu2+ ions using catalytic DNA
Cristina Ocaña ,  Natalia Malashikhina ,  Manel del Valle and Valeri Pavlov
Analyst, 2013,138, 1995-1999 
DOI: 10.1039/C3AN36778A

Chitosan-capped silver nanoparticles as a highly selective colorimetric probe for visual detection of aromatic ortho-trihydroxy phenols
Zhaohui Chen ,  Xiaodan Zhang ,  Haiyan Cao and Yuming Huang
Analyst, 2013, e
DOI: 10.1039/C3AN36905F

Hairpin oligonucleotides anchored terbium ion: a fluorescent probe to specifically detect lead(II) at sub-nM levels
Yueteng Wei ,  Ru Liu ,  Yaling Wang ,  Yuliang Zhao ,  Zhifang Cai and Xueyun Gao
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36795A

Schematic interaction between Ce3+ and phosphate

Guang-Li Wang and co-workers, from the Jiangnan University, China, have developed an assay to detect the level of phosphate in water. 

Ce³⁺ ions are used to aggregate citrate-capped silver nanoparticles with cysteine-capped quantum dots, thereby causing efficient quenching of the fluorescence signal.  However, when phosphate is introduced to the system it interacts with the Ce³⁺ ions causing the quenched aggregates to redisperse and switching the fluorescent signal from “off” to “on”.  This work has potential applications for the environmental analysis of groundwater.

To read more about this work, please access this Analyst HOT article below. It will be free to read until March 8th.

Novel switchable sensor for phosphate based on the distance-dependant fluorescence coupling of cysteine-capped cadmium sulfide quantum dots and silver nanoparticles
Guang-Li Wang ,  Huan-Jun Jiao ,  Xiao-Ying Zhu ,  Yu-Ming Dong and Zai-Jun Li
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36878E

Schematic picture of a hybrid instrument correlating different spectral imaging modes

Scientists use chemical imaging to address a variety of issues visualising the arrangement of atoms, the content of single cells or the colourless gases released into Earth’s atmosphere by cities of kilometre scale. Many analytical techniques have been developed to date and researchers are now interested in combining the different imaging modalities to increase and improve the information gathered from imaging experiments.

In this new Critical Review just published in Analyst Paul Bohn and his group at the University of Notre Dame, USA, explore all the latest imaging techniques and introduce the new area of Raman imaging and mass spectrometry in the field of correlated imaging.

To know more, please access the full article below. It will be free to read until March 8th.

Correlated imaging – a grand challenge in chemical analysis
Rachel Masyuko ,  Eric J. Lanni ,  Jonathan V. Sweedler and Paul W. Bohn
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36416J

Overview of DNA Detection Using Fiber Optic Biosensor

Ming-jie Yin and others from The Hong Kong Polytechnic University in China have made the latest stride towards development of label-free fiber-optic biosensors for DNA detection.

Their new design involves fabrication of a DNA sensor as part of a thin sensing film on the surface of a thin-core fiber modal interferometer (TCFMI) to measure differences in refractive-index upon detection of target DNA sequences. The research team makes use of a layer-by-layer self-assembly approach, which enables controlled tunability in preparation of the sensing film.

Unlike many other reported fiber-optic biosensing methods, this current strategy confers the advantages of high detection sensitivity, lower cost and ease in preparation.

Read more about the latest discovery by accessing the link below. This article will be free to read until March 6th.

Label-free, disposable fiber-optic biosensors for DNA hybridization detection
Ming-jie Yin ,  Chuang Wu ,  Li-yang Shao ,  Wing Kin Edward Chan ,  A. Ping Zhang ,  Chao Lu and Hwa-yaw Tam
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36791F

In the latest issue of Analyst we have some wonderful HOT articles for you to read. They cover a wide variety of topics including iodine determination by optical emission spectrometry, detection of trinitrotoluene in seawater, and immunosensors for surface plasmon field-enhanced fluorescence spectroscopy in serum.

If you want to know more about the latest discoveries published in Analyst, take a look at the papers below, they will be free to read until February 28th.

Iodine excitation in a dielectric barrier discharge micro-plasma and its determination by optical emission spectrometry
Yong-Liang Yu ,  Shuai Dou ,  Ming-Li Chen and Jian-Hua Wang
Analyst, 2013, Advance Article
DOI: 10.1039/C2AN36780G

Graphenes prepared from multi-walled carbon nanotubes and stacked graphene nanofibers for detection of 2,4,6-trinitrotoluene (TNT) in seawater
Shu Min Tan ,  Chun Kiang Chua and Martin Pumera
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN00089C

Graphene nanopfibers for detection of trinitrotoluene

A mixed alkanethiol based immunosensor for surface plasmon field-enhanced fluorescence spectroscopy in serum
Andreas Scholten ,  Bernhard Menges ,  Martin Juebner ,  Markus A. Rothschild and Katja Bender
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN35657D

Facile formation of folic acid-modified dendrimer-stabilized gold–silver alloy nanoparticles for potential cellular computed tomography imaging applications
Hui Liu ,  Mingwu Shen ,  Jinglong Zhao ,  Jingyi Zhu ,  Tingting Xiao ,  Xueyan Cao ,  Guixiang Zhang and Xiangyang Shi
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36649A

In-process phase growth measurement technique in the fabrication of monolithic porous layer open tubular (monoPLOT) columns using capacitively coupled contactless conductivity
David A. Collins ,  Ekaterina P. Nesterenko ,  Dermot Brabazon and Brett Paull
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN00133D

Using nanoparticles for diagnosis and drug release

A vast array of illnesses can be diagnosed by detecting specific proteins or fragments of DNA in the body. But is it possible to build a 2-in-1 system which both detects a disease and provides treatment?

Researchers at Nankai University, China, have created the first functioning system for simultaneous diagnosis and controlled drug release, a so-called “diagnospy” carrier.   To demonstrate the concept, De-Ming Kong and co-workers constructed a mesoporous phosphonate-TiO₂ nanoparticle scaffold loaded with ibuprofen. The amino groups on the phosphonates hold fluorescein-labelled single strands of DNA in place over the porous surface, trapping the drug molecules inside. When a complementary target strand is present, a displacement reaction uncaps the pores and the drug is released.

This mechanism relies on the highly specific affinity between complementary strands of DNA, or between proteins and their aptamers, resulting in a very sensitive detection and drug delivery system. The simultaneous sense-and-release approach is hoped to make treatments more efficient and convenient for patients in the future.

To find out more, please access the full article below. It will be free to read for the next two weeks.

Mesoporous phosphonate-TiO₂ nanoparticles for simultaneous bioresponsive sensing and controlled drug release
Hui Li,  Tian-Yi Ma,  De-Ming Kong and Zhong-Yong Yuan
Analyst, 2013, 138, 1084-1090
DOI: 10.1039/C2AN36631B

The cell effectively uses the mechanism of pH fluctuation as a form of regulatory control for diverse physiological functions. Over the years, optical based methods have been used to develop chemosensors to measure the dynamics of intracellular pH, some of which have demonstrated considerable potential for biological applications.

Wei Huang and colleagues from the Nanjing University of Posts and Telecommunications, China, have developed the latest optical pH probes by making use of cyclometalated iridium (III) complexes, a well known phosphorescent emitter. Huang’s group has expanded the repertoire of useful chemosensors by synthesizing and characterizing the photophysical properties of two iridium (III) complexes using a novel substituent, carboxylic-acid.

Find out more about their discovery by accessing the link below. This paper will be free to read for the next two weeks.

Effect of pH on the photophysical properties of two new carboxylic-substituted iridium(III) complexes
Jiena Weng ,  Qunbo Mei ,  Weiwei Jiang ,  Quli Fan ,  Bihai Tong ,  Qidan Ling and Wei Huang
Analyst, 2013, Advance Article
DOI: 10.1039/C2AN36298H

pH effect on carboxylic-substituted iridium(III) complex

Along with Analyst Issue 5, here is a list of selected HOT articles for you to read all about. Topics vary from lipid imaging by mass spectrometry to determination of drugs by titanium oxide nanoparticles. Featured below are the work of Asit Baran Mandal and colleagues who present a new single molecular FRET-based sensor for determination of iron, and a study from the National Sun Yat-sen University, Taiwan, on direct monitoring of chemical transformations. All these papers will be free to read until February 28th. Have a read now!

Lipid imaging by mass spectrometry – a review
David Gode and Dietrich A. Volmer
Analyst, 2013,138, 1289-1315
DOI: 10.1039/C2AN36337B

Single molecular FRET-based sensor for detection of Fe2+

A highly selective and efficient single molecular FRET based sensor for ratiometric detection of Fe3+ ions
Narendra Reddy Chereddy ,  Sathiah Thennarasu and Asit Baran Mandal
Analyst, 2013,138, 1334-1337
DOI: 10.1039/C3AN36577H

Impact of charge state on gas-phase behaviors of noncovalent protein complexes in collision induced dissociation and surface induced dissociation
Mowei Zhou ,  Shai Dagan and Vicki H. Wysocki
Analyst, 2013,138, 1353-1362
DOI: 10.1039/C2AN36525A

TLC with MALDI-MS to monitor chemical transformations

Direct monitoring of chemical transformations by combining thin layer chromatography with nanoparticle-assisted laser desorption/ionization mass spectrometry
Chun-Chi Chen ,  Yung-Lin Yang ,  Chun-Lin Ou ,  Chih-Hung Chou ,  Chih-Chuang Liaw and Po-Chiao Lin
Analyst, 2013,138, 1379-1385
DOI: 10.1039/C2AN36423A

Mass spectrometry sequencing of transfer ribonucleic acids by the comparative analysis of RNA digests (CARD) approach
Siwei Li and Patrick A. Limbach
Analyst, 2013,138, 1386-1394
DOI: 10.1039/C2AN36515D 

Adsorptive stripping voltammetric determination of imipramine, trimipramine and desipramine employing titanium dioxide nanoparticles and an Amberlite XAD-2 modified glassy carbon paste electrode
Bankim J. Sanghavi and Ashwini K. Srivastava
Analyst, 2013,138, 1395-1404
DOI: 10.1039/C2AN36330E

Electrical, enzymatic graphene biosensing of 5-aminosalicylic acid
Pratima Labroo and Yue Cui
Analyst, 2013,138, 1325-1328
DOI: 10.1039/C3AN36660J

Ruqin Yu and colleagues from the University of Hunan, China, have developed a label-free fluorescent detection system for glutathione (GSH) and cysteine (Cys). 

Hg2+ mediated fluorescent sensing strategy for detection of GSH and Cys

Three key interactions are necessary for the development of this assay: two single stranded DNA with thymine-thymine (T•T) mismatches stabilised in the presence of Hg2+, GSH and Cys interaction with Hg2+ with much higher binding affinity than T•T mismatches, and interaction of N-methyl porphyrin IX (MMP) with G-quadruplex structures, which leads to increased fluorescence.
The researchers  judiciously designed two sequences of DNA such that inter-molecular T•T mismatches were stabilised in the presence of Hg2+, inhibiting one of the stands from forming a G-quadruplex.  When the Hg2+ interacts with GSH or Cys, an intramolecular G-quadruplex is formed.  The G-quadruplex interacts with the NMM producing a marked increase in fluorescence.  Contrarily, in the absence of GSH and Cys, the Hg2+ is available to stabilise the mismatched duplex, the G-quadruplex is not formed, no NMM binding occurs and no fluorescent increase is observed.

This system was successfully used to detect GSH or Cys from protein extracted from human serum samples. To read more about this work, please access the full article below. It will be free to read until February 28th.

A Hg2+-mediated label-free fluorescent sensing strategy based on G-quadruplex formation for selective detection of glutathione and cysteine
Jingjin Zhao ,  Chunfei Chen ,  Liangliang Zhang ,  Jianhui Jiang ,  Guoli Shen and Ruqin Yu
Analyst, 2013, Advance Article
DOI: 10.1039/C3AN36657J