Wenwan Zhong - Academia.edu (original) (raw)

Papers by Wenwan Zhong

Analytical and Bioanalytical Chemistry, 2021

Development of new capillary electrophoresis (CE) methodology and instrumentation, as well as app... more Development of new capillary electrophoresis (CE) methodology and instrumentation, as well as application of CE to solve new problems, remains an active research area because of the attractive features of CE compared to other separation techniques. In this review, we focus on the representative works about sample preconcentration, separation media or capillary coating development, detector construction, and multidimensional separation in CE, which are judiciously selected from the papers published in 2018-2020.

Analytical Chemistry, 2019

Extracellular vesicles (EVs) are cell-derived membranous vesicles that exist in nearly all biolog... more Extracellular vesicles (EVs) are cell-derived membranous vesicles that exist in nearly all biological fluids including blood and urine; and carry a great number of cargo molecules such as protein, DNA, RNA and lipid. They may play important roles in cell-cell communication and modulation of pathological processes, which, however, are not yet well understood, calling for highly sensitive, specific, and rapid methods for EV detection and quantification in biological samples. Here, we report the CuS-enclosed microgels that not only help enrich EVs carrying specific protein markers from complex biomatrices, but also produce strong chemiluminescence (CL) to realize sensitive detection of the target EVs. A detection limit of 10 4 EV particles/mL was achieved with these microgels by targeting EV proteins like CD63 and HER2, with a dynamic range up to 10 8 particles/mL. Direct detection of EVs in human serum and cell culture medium without tedious sample preparation was demonstrated, consuming much less sample compared to ELISA and Western Blot. We envision that our method will be valuable for quick quantification of EVs in biological samples, benefiting disease monitoring and functional study.

Chemical Communications, 2019

A host-guest based fluorescence sensor array can sense small differences in protein structure. Th... more A host-guest based fluorescence sensor array can sense small differences in protein structure. The combination of three cavitand hosts and two fluorophores to form a 4-component array is sufficient to...

Analytical Chemistry, 2019

The molecular structure of a protein could be altered when attached to nanoparticles (NPs), affec... more The molecular structure of a protein could be altered when attached to nanoparticles (NPs), affecting the performance of NPs present in biological systems. Limited proteolysis coupled with LC-MS/MS could reveal the changes in protein structure when it binds to a variety of entities, including macro-molecules and small drugs, but has not yet been applied to study protein-NP interaction. Herein, adsorption of proteins, transferrin and catalase, on the polystyrene (PS) or iron oxide (IO) NPs was analyzed with this method. Both increased and decreased proteolytic efficiency in certain regions on the proteins were observed. Identification of the peptides affected by protein-NP interaction led to proper prediction of alterations to protein function as well as to colloidal stability of NPs. Overall, the present work has demonstrated the utility of limited proteolysis in helping elucidate the potential biological outcomes of the protein-NP conjugate, obtaining knowledge to guide improvement of the rational design of the protein conjugated NPs for biomedical applications, and to understand the biological behaviors of the engineered NPs. Protein adsorption on the surface of engineered nanoparticles (NPs) unintentionally exposed to biological systems is inevitable. 1-5 On the other hand, intentionally attaching specific proteins (i.e. antibodies) on NPs as the target recognition moieties has also been used to achieve active targeting and assist delivery of NPs for therapeutic purposes. 6-8 While the adsorbed protein corona could be beneficial to the outcomes of the NPs by keeping the NPs from being cleared by the innate immune system; 9-11 structural changes, e.g. unfolding, fibrillation and aggregation, 12-14 could occur to the protein after binding to the NPs, and induce negative impacts on the protein-NP conjugates. 7,15,16 For example, protein unfolding can expose the originally buried cryptic epitopes to induce immune clearance of the NPs and

Chemistry – A European Journal, 2018

Arrayed complexes of a water-soluble deep cavitand and two fluorescent indicators show selective ... more Arrayed complexes of a water-soluble deep cavitand and two fluorescent indicators show selective sensing of anabolicandrogenic steroids in aqueous environments. By combining the host:guest complexes with small amounts of heavy metal ions, discrimination between steroids that vary in structure by only a single π bond is possible. The sensing occurs via a triggered aggregation mechanism, which can be mediated by both the presence of metal ions and the steroids. The use of both "turn-on" and "turn-off" fluorophores is essential for good discrimination. As low as 10 µM steroid can be detected, and the discrimination is selective in steroid samples spiked into human urine.

Chemical Communications, 2018

A synergistic combination of a deep cavitand host, fluorophore guests and transition metal ions c... more A synergistic combination of a deep cavitand host, fluorophore guests and transition metal ions can be used to sense small molecule thiols of biological interest with good efficiency and selectivity in complex aqueous media.

Journal of the American Chemical Society, 2018

Simple tuning of a host: guest pair allows selective sensing of different peptide modifications, ... more Simple tuning of a host: guest pair allows selective sensing of different peptide modifications, exploiting orthogonal recognition mechanisms. Excellent selectivity for either lysine trimethylations or alcohol phosphorylations is possible by simply varying the fluorophore guest. The phosphorylation sensor can be modulated by the presence of small (μM) concentrations of metal ions, allowing array-based sensing. Phosphorylation at serine, threonine and tyrosine can be selectively sensed via discriminant analysis. The phosphopeptide sensing is effective in the presence of small molecule phosphates such as ATP, which in turn enables the sensor to be employed in continuous optical assays of both serine kinase and tyrosine phosphatase activity. The activity of multiple different kinases can be monitored, and the sensor is capable of detecting the phosphorylation of peptides containing multiple different modifications, including lysine methylations and acetylation. A single deep cavitand c...

Encapsulation of ionic nanoparticles produces reactive oxygen species (ROS)-responsive microgel useful for molecular detection

Chemical communications (Cambridge, England), Jan 11, 2018

Encapsulation of ionic nanoparticles in a hydrogel microparticle, i.e. microgel, produces a targe... more Encapsulation of ionic nanoparticles in a hydrogel microparticle, i.e. microgel, produces a target-stimulated probe for molecular detection. Selective reactive oxygen species (ROS) release the enclosed cations from the microgel which subsequently turn on the fluorogenic dyes to emit intense fluorescence, permitting rapid detection of ROS or ROS-producing molecules. The ROS-responsive microgel provides the advantages of simple fabrication, bright and stable signals, easy handling, and rapid response, carrying great promise in biomedical applications.

Analytical chemistry, Jan 8, 2018

Exosomes play important roles in mediating intercellular communication and regulating a variety o... more Exosomes play important roles in mediating intercellular communication and regulating a variety of biological processes, but clear understanding of their functions and biogenesis has not been achieved, due to the high technical difficulties involved in analysis of small vesicular structures that contain a high proportion of membrane structures. Herein, we designed a novel approach to integrate two nanomaterials carrying varied surface properties, the hydrophilic, macroporous graphene foam (GF) and the amphiphilic periodic mesoporous organosilica (PMO), for efficient exosome isolation from human serum and effective protein profiling. The high specific surface area of GF, after modification with the antibody against the exosomal protein marker, CD63, allowed highly specific isolation of exosomes from complex biological samples with high recovery. Since the organic solvent, methanol, turned out to be the most effective lysis solution for releasing the exosomal proteins, the amphiphilic...

Analytical chemistry, Feb 17, 2018

Lysine methylation in protein is one important epigenetic mechanism that regulates diverse biolog... more Lysine methylation in protein is one important epigenetic mechanism that regulates diverse biological processes but is challenging to study due to the large variability in methylation levels and sites. Here, we show that supramolecular hosts such as calixarenes and cucurbiturils can be applied in the background electrolyte (BGE) of capillary electrophoresis (CE) for highly effective separation of post-translationally methylated histone peptides. The molecular recognition event causes a shift in the electrophoretic mobility of the peptide, allowing affinity measurement for binding between the synthetic receptor and various methylated lysine species. Successful separation of the H3 peptides carrying different methylation levels at the K9 position can be achieved using CX4 and CX6 as the BGE additives in CE, enabling monitoring of the activity of the histone lysine demethylase JMJD2E. This reveals the power of combining high resolution CE with synthetic hosts for study of protein methy...

Analytical chemistry, Jan 27, 2017

Nanomaterials have shown great promise in advancing biomedical and environmental analysis because... more Nanomaterials have shown great promise in advancing biomedical and environmental analysis because of the unique properties originated from their ultrafine dimensions. In general, nanomaterials are separately applied to either enhance detection by producing strong signals upon target recognition or to specifically extract analytes taking advantage of their high specific surface area. Herein, we report a dual-functional nanomaterial-based platform that can simultaneously enrich and enable sensitive detection of multiple metal ions. The macroporous graphene foam (GF) we prepared displays abundant phosphate groups on the surface and can extract divalent metal ions via metal-phosphate coordination. The enriched metal ions then activate the metal-responsive DNAzymes and produce the fluorescently labeled single-stranded DNAs that are adsorbed and quenched by the GF. The resultant fluorescence reduction can be used for metal quantitation. The present work demonstrated duplexed detection of ...

Analytical chemistry, Jan 30, 2017

Protein adsorption alters the "biological identity" of the nanoparticles (NPs) and coul... more Protein adsorption alters the "biological identity" of the nanoparticles (NPs) and could affect how biosystems respond to the invading NPs. Study of protein-NP interaction can help understand how the physicochemical properties of NPs impact the interaction and thus potentially guide the design of safer and more effective NPs for biomedical or other applications. Binding affinity between proteins and NPs, and the occurrence of protein conformational change upon binding to NPs are two important aspects to be learned, but few methods are currently available to assess both simultaneously in a simple way. Herein, we demon-strated that the fluorescamine labeling method developed in our group could not only reveal protein conformational change upon adsorption to NPs, owing to its capability to label the primary amines exposed on protein surface, but also it could be applied to measure the binding affinity. By screening the interaction between a large number of proteins and four t...

Analytical Chemistry, 2017

A simple three component array of host:fluorophore complexes is capable of sensitive and selectiv... more A simple three component array of host:fluorophore complexes is capable of sensitive and selective discrimination of heavy metal ions, including lanthanide and actinide salts in aqueous solution. Instead of applying optical sensors that only use "singlemode" detection, i.e. coordination of the metal to a specific ligand and monitoring the change in emission of an appended fluorophore, we exploit a series of host:fluorophore complexes that are affected by the presence of small amounts of metal ions in aqueous solution in different ways. Variable host:metal and host:guest:metal interactions lead to both turn-on and turn-off fluorescence sensing mechanisms, enhancing the discriminatory properties of the array. The limit of detection for certain metals is as low as 70 nM, and highly similar metals such as lanthanides and actinides can be easily distinguished at low micromolar concentrations in complex salt mixtures.

Journal of the American Chemical Society, Aug 16, 2017

Arrayed deep cavitands can be coupled to a fluorescence-based supramolecular tandem assay that al... more Arrayed deep cavitands can be coupled to a fluorescence-based supramolecular tandem assay that allows site-selective in situ monitoring of post-translational modifications catalyzed by the lysine methyltransferase PRDM9 or the lysine demethylase JMJD2E. An arrayed sensor system containing only three cavitand components can detect the specific substrates of enzyme modification, in the presence of other histone peptides in the enzyme assay, enabling investigation of cross-reactivity over multiple methylation sites and interference from nonsubstrate peptides.

Chemical Science, 2017

Arrayed, self-folding deep cavitands form a fluorescence displacement assay system for the site-s... more Arrayed, self-folding deep cavitands form a fluorescence displacement assay system for the site-selective sensing of post-translationally modified (PTM) histone peptides.

Journal of the American Chemical Society, Aug 16, 2016

A dual-mode aggregative host:guest indicator displacement sensing system has been created for the... more A dual-mode aggregative host:guest indicator displacement sensing system has been created for the detection of trimethylated peptides and determination of histone demethylase activity. The combination of selective recognition of suitably sized trimethylammonium salts and reversible lipophilic aggregation of the host:guest complex provides a unique quenching mechanism that is not only dependent on affinity for sensitivity but the lipophilicity of the indicator. In addition, aggregation can be controlled by the application of chaotropic anions in the mixture, allowing a second level of discrimination between hard lysine groups and softer trimethyllysines.

Chemical communications (Cambridge, England), Jan 23, 2015

An amine-reactive fluorogenic molecule specifically turned on by superoxide radicals (O2˙(-)) was... more An amine-reactive fluorogenic molecule specifically turned on by superoxide radicals (O2˙(-)) was synthesized and coupled to a mitochondrial (MT) targeting peptide. The obtained probe showed superior uptake and MT targeting capabilities; and successfully detected the change in O2˙(-) levels in cells treated with chemical stimuli or single-walled carbon nanotubes.

CHAPTER 1. GENERAL INTRODUCTION I Dissertation Organization I Capillary Electrophoresis Related D... more CHAPTER 1. GENERAL INTRODUCTION I Dissertation Organization I Capillary Electrophoresis Related DNA T echniques Our Goal References CHAPTER 2. MULTIPLEXED CAPILLARY ELECTROPHORESIS FOR DNA SEQUENCING WITH UV ABSORPTION DETECTION Abstract Introduction Material and Methods Results and Discussion Conclusion Remarks Acknowledgement References CHAPTER 3. COMBINATORIAL ENANTIOMERIC SEPARATION OF DIVERSE COMPOUNDS USING CAPILLARY ARRAY ELECTROPHORESIS Abstract Introduction Experimental Section Results and Discussion Conclusions Acknowledgement References CHAPTER 4. HIGH THROUGHPUT ANALYSIS OF TOTAL RNA EXPRESSION PROFILE BY CAPILLARY ELECTROPHORESIS 91 Abstract.... Introduction Experimental Section Results and Discussion Conclusions Acknowledgement References

Journal of Chromatography A, 2014

Tools capable of measuring binding affinities as well as amenable to downstream sequencing analys... more Tools capable of measuring binding affinities as well as amenable to downstream sequencing analysis are needed for study of DNA-protein interaction, particularly in discovery of new DNA sequences with affinity to diverse targets. Asymmetrical flow field-flow fractionation (AF4) is an open-channel separation technique that eliminates interference from column packing to the non-covalently bound complex and could potentially be applied for study of macromolecular interaction. The recovery and elution behaviors of the poly(dA) n strand and aptamers in AF4 were investigated. Good recovery of ssDNAs was achieved by judicious selection of the channel membrane with consideration of the membrane pore diameter and the radius of gyration (R g) of the ssDNA, which was obtained with the aid of a Molecular Dynamics tool. The R g values were also used to assess the folding situation of aptamers based on their migration times in AF4. The interactions between two ssDNA aptamers and their respective protein components were investigated. Using AF4, near-baseline resolution between the free and protein-bound aptamer fractions could be obtained. With this information, dissociation constants of ~16nM and ~57 nM were obtained for an IgE aptamer and a streptavidin aptamer, respectively. In addition, free and protein-bound IgE aptamer was extracted from the AF4 eluate and amplified, illustrating the potential of AF4 in screening ssDNAs with high affinity to targets. Our results demonstrate that AF4 is an effective tool holding several advantages over the existing techniques and should be useful for study of diverse macromolecular interaction systems.

The Analyst, 2014

Protein adsorption is sensitive enough to detect structural changes in the head group of the poly... more Protein adsorption is sensitive enough to detect structural changes in the head group of the polymeric ligand.

Analytical and Bioanalytical Chemistry, 2021

Development of new capillary electrophoresis (CE) methodology and instrumentation, as well as app... more Development of new capillary electrophoresis (CE) methodology and instrumentation, as well as application of CE to solve new problems, remains an active research area because of the attractive features of CE compared to other separation techniques. In this review, we focus on the representative works about sample preconcentration, separation media or capillary coating development, detector construction, and multidimensional separation in CE, which are judiciously selected from the papers published in 2018-2020.

Analytical Chemistry, 2019

Extracellular vesicles (EVs) are cell-derived membranous vesicles that exist in nearly all biolog... more Extracellular vesicles (EVs) are cell-derived membranous vesicles that exist in nearly all biological fluids including blood and urine; and carry a great number of cargo molecules such as protein, DNA, RNA and lipid. They may play important roles in cell-cell communication and modulation of pathological processes, which, however, are not yet well understood, calling for highly sensitive, specific, and rapid methods for EV detection and quantification in biological samples. Here, we report the CuS-enclosed microgels that not only help enrich EVs carrying specific protein markers from complex biomatrices, but also produce strong chemiluminescence (CL) to realize sensitive detection of the target EVs. A detection limit of 10 4 EV particles/mL was achieved with these microgels by targeting EV proteins like CD63 and HER2, with a dynamic range up to 10 8 particles/mL. Direct detection of EVs in human serum and cell culture medium without tedious sample preparation was demonstrated, consuming much less sample compared to ELISA and Western Blot. We envision that our method will be valuable for quick quantification of EVs in biological samples, benefiting disease monitoring and functional study.

Chemical Communications, 2019

A host-guest based fluorescence sensor array can sense small differences in protein structure. Th... more A host-guest based fluorescence sensor array can sense small differences in protein structure. The combination of three cavitand hosts and two fluorophores to form a 4-component array is sufficient to...

Analytical Chemistry, 2019

The molecular structure of a protein could be altered when attached to nanoparticles (NPs), affec... more The molecular structure of a protein could be altered when attached to nanoparticles (NPs), affecting the performance of NPs present in biological systems. Limited proteolysis coupled with LC-MS/MS could reveal the changes in protein structure when it binds to a variety of entities, including macro-molecules and small drugs, but has not yet been applied to study protein-NP interaction. Herein, adsorption of proteins, transferrin and catalase, on the polystyrene (PS) or iron oxide (IO) NPs was analyzed with this method. Both increased and decreased proteolytic efficiency in certain regions on the proteins were observed. Identification of the peptides affected by protein-NP interaction led to proper prediction of alterations to protein function as well as to colloidal stability of NPs. Overall, the present work has demonstrated the utility of limited proteolysis in helping elucidate the potential biological outcomes of the protein-NP conjugate, obtaining knowledge to guide improvement of the rational design of the protein conjugated NPs for biomedical applications, and to understand the biological behaviors of the engineered NPs. Protein adsorption on the surface of engineered nanoparticles (NPs) unintentionally exposed to biological systems is inevitable. 1-5 On the other hand, intentionally attaching specific proteins (i.e. antibodies) on NPs as the target recognition moieties has also been used to achieve active targeting and assist delivery of NPs for therapeutic purposes. 6-8 While the adsorbed protein corona could be beneficial to the outcomes of the NPs by keeping the NPs from being cleared by the innate immune system; 9-11 structural changes, e.g. unfolding, fibrillation and aggregation, 12-14 could occur to the protein after binding to the NPs, and induce negative impacts on the protein-NP conjugates. 7,15,16 For example, protein unfolding can expose the originally buried cryptic epitopes to induce immune clearance of the NPs and

Chemistry – A European Journal, 2018

Arrayed complexes of a water-soluble deep cavitand and two fluorescent indicators show selective ... more Arrayed complexes of a water-soluble deep cavitand and two fluorescent indicators show selective sensing of anabolicandrogenic steroids in aqueous environments. By combining the host:guest complexes with small amounts of heavy metal ions, discrimination between steroids that vary in structure by only a single π bond is possible. The sensing occurs via a triggered aggregation mechanism, which can be mediated by both the presence of metal ions and the steroids. The use of both "turn-on" and "turn-off" fluorophores is essential for good discrimination. As low as 10 µM steroid can be detected, and the discrimination is selective in steroid samples spiked into human urine.

Chemical Communications, 2018

A synergistic combination of a deep cavitand host, fluorophore guests and transition metal ions c... more A synergistic combination of a deep cavitand host, fluorophore guests and transition metal ions can be used to sense small molecule thiols of biological interest with good efficiency and selectivity in complex aqueous media.

Journal of the American Chemical Society, 2018

Simple tuning of a host: guest pair allows selective sensing of different peptide modifications, ... more Simple tuning of a host: guest pair allows selective sensing of different peptide modifications, exploiting orthogonal recognition mechanisms. Excellent selectivity for either lysine trimethylations or alcohol phosphorylations is possible by simply varying the fluorophore guest. The phosphorylation sensor can be modulated by the presence of small (μM) concentrations of metal ions, allowing array-based sensing. Phosphorylation at serine, threonine and tyrosine can be selectively sensed via discriminant analysis. The phosphopeptide sensing is effective in the presence of small molecule phosphates such as ATP, which in turn enables the sensor to be employed in continuous optical assays of both serine kinase and tyrosine phosphatase activity. The activity of multiple different kinases can be monitored, and the sensor is capable of detecting the phosphorylation of peptides containing multiple different modifications, including lysine methylations and acetylation. A single deep cavitand c...

Encapsulation of ionic nanoparticles produces reactive oxygen species (ROS)-responsive microgel useful for molecular detection

Chemical communications (Cambridge, England), Jan 11, 2018

Encapsulation of ionic nanoparticles in a hydrogel microparticle, i.e. microgel, produces a targe... more Encapsulation of ionic nanoparticles in a hydrogel microparticle, i.e. microgel, produces a target-stimulated probe for molecular detection. Selective reactive oxygen species (ROS) release the enclosed cations from the microgel which subsequently turn on the fluorogenic dyes to emit intense fluorescence, permitting rapid detection of ROS or ROS-producing molecules. The ROS-responsive microgel provides the advantages of simple fabrication, bright and stable signals, easy handling, and rapid response, carrying great promise in biomedical applications.

Analytical chemistry, Jan 8, 2018

Exosomes play important roles in mediating intercellular communication and regulating a variety o... more Exosomes play important roles in mediating intercellular communication and regulating a variety of biological processes, but clear understanding of their functions and biogenesis has not been achieved, due to the high technical difficulties involved in analysis of small vesicular structures that contain a high proportion of membrane structures. Herein, we designed a novel approach to integrate two nanomaterials carrying varied surface properties, the hydrophilic, macroporous graphene foam (GF) and the amphiphilic periodic mesoporous organosilica (PMO), for efficient exosome isolation from human serum and effective protein profiling. The high specific surface area of GF, after modification with the antibody against the exosomal protein marker, CD63, allowed highly specific isolation of exosomes from complex biological samples with high recovery. Since the organic solvent, methanol, turned out to be the most effective lysis solution for releasing the exosomal proteins, the amphiphilic...

Analytical chemistry, Feb 17, 2018

Lysine methylation in protein is one important epigenetic mechanism that regulates diverse biolog... more Lysine methylation in protein is one important epigenetic mechanism that regulates diverse biological processes but is challenging to study due to the large variability in methylation levels and sites. Here, we show that supramolecular hosts such as calixarenes and cucurbiturils can be applied in the background electrolyte (BGE) of capillary electrophoresis (CE) for highly effective separation of post-translationally methylated histone peptides. The molecular recognition event causes a shift in the electrophoretic mobility of the peptide, allowing affinity measurement for binding between the synthetic receptor and various methylated lysine species. Successful separation of the H3 peptides carrying different methylation levels at the K9 position can be achieved using CX4 and CX6 as the BGE additives in CE, enabling monitoring of the activity of the histone lysine demethylase JMJD2E. This reveals the power of combining high resolution CE with synthetic hosts for study of protein methy...

Analytical chemistry, Jan 27, 2017

Nanomaterials have shown great promise in advancing biomedical and environmental analysis because... more Nanomaterials have shown great promise in advancing biomedical and environmental analysis because of the unique properties originated from their ultrafine dimensions. In general, nanomaterials are separately applied to either enhance detection by producing strong signals upon target recognition or to specifically extract analytes taking advantage of their high specific surface area. Herein, we report a dual-functional nanomaterial-based platform that can simultaneously enrich and enable sensitive detection of multiple metal ions. The macroporous graphene foam (GF) we prepared displays abundant phosphate groups on the surface and can extract divalent metal ions via metal-phosphate coordination. The enriched metal ions then activate the metal-responsive DNAzymes and produce the fluorescently labeled single-stranded DNAs that are adsorbed and quenched by the GF. The resultant fluorescence reduction can be used for metal quantitation. The present work demonstrated duplexed detection of ...

Analytical chemistry, Jan 30, 2017

Protein adsorption alters the "biological identity" of the nanoparticles (NPs) and coul... more Protein adsorption alters the "biological identity" of the nanoparticles (NPs) and could affect how biosystems respond to the invading NPs. Study of protein-NP interaction can help understand how the physicochemical properties of NPs impact the interaction and thus potentially guide the design of safer and more effective NPs for biomedical or other applications. Binding affinity between proteins and NPs, and the occurrence of protein conformational change upon binding to NPs are two important aspects to be learned, but few methods are currently available to assess both simultaneously in a simple way. Herein, we demon-strated that the fluorescamine labeling method developed in our group could not only reveal protein conformational change upon adsorption to NPs, owing to its capability to label the primary amines exposed on protein surface, but also it could be applied to measure the binding affinity. By screening the interaction between a large number of proteins and four t...

Analytical Chemistry, 2017

A simple three component array of host:fluorophore complexes is capable of sensitive and selectiv... more A simple three component array of host:fluorophore complexes is capable of sensitive and selective discrimination of heavy metal ions, including lanthanide and actinide salts in aqueous solution. Instead of applying optical sensors that only use "singlemode" detection, i.e. coordination of the metal to a specific ligand and monitoring the change in emission of an appended fluorophore, we exploit a series of host:fluorophore complexes that are affected by the presence of small amounts of metal ions in aqueous solution in different ways. Variable host:metal and host:guest:metal interactions lead to both turn-on and turn-off fluorescence sensing mechanisms, enhancing the discriminatory properties of the array. The limit of detection for certain metals is as low as 70 nM, and highly similar metals such as lanthanides and actinides can be easily distinguished at low micromolar concentrations in complex salt mixtures.

Journal of the American Chemical Society, Aug 16, 2017

Arrayed deep cavitands can be coupled to a fluorescence-based supramolecular tandem assay that al... more Arrayed deep cavitands can be coupled to a fluorescence-based supramolecular tandem assay that allows site-selective in situ monitoring of post-translational modifications catalyzed by the lysine methyltransferase PRDM9 or the lysine demethylase JMJD2E. An arrayed sensor system containing only three cavitand components can detect the specific substrates of enzyme modification, in the presence of other histone peptides in the enzyme assay, enabling investigation of cross-reactivity over multiple methylation sites and interference from nonsubstrate peptides.

Chemical Science, 2017

Arrayed, self-folding deep cavitands form a fluorescence displacement assay system for the site-s... more Arrayed, self-folding deep cavitands form a fluorescence displacement assay system for the site-selective sensing of post-translationally modified (PTM) histone peptides.

Journal of the American Chemical Society, Aug 16, 2016

A dual-mode aggregative host:guest indicator displacement sensing system has been created for the... more A dual-mode aggregative host:guest indicator displacement sensing system has been created for the detection of trimethylated peptides and determination of histone demethylase activity. The combination of selective recognition of suitably sized trimethylammonium salts and reversible lipophilic aggregation of the host:guest complex provides a unique quenching mechanism that is not only dependent on affinity for sensitivity but the lipophilicity of the indicator. In addition, aggregation can be controlled by the application of chaotropic anions in the mixture, allowing a second level of discrimination between hard lysine groups and softer trimethyllysines.

Chemical communications (Cambridge, England), Jan 23, 2015

An amine-reactive fluorogenic molecule specifically turned on by superoxide radicals (O2˙(-)) was... more An amine-reactive fluorogenic molecule specifically turned on by superoxide radicals (O2˙(-)) was synthesized and coupled to a mitochondrial (MT) targeting peptide. The obtained probe showed superior uptake and MT targeting capabilities; and successfully detected the change in O2˙(-) levels in cells treated with chemical stimuli or single-walled carbon nanotubes.

CHAPTER 1. GENERAL INTRODUCTION I Dissertation Organization I Capillary Electrophoresis Related D... more CHAPTER 1. GENERAL INTRODUCTION I Dissertation Organization I Capillary Electrophoresis Related DNA T echniques Our Goal References CHAPTER 2. MULTIPLEXED CAPILLARY ELECTROPHORESIS FOR DNA SEQUENCING WITH UV ABSORPTION DETECTION Abstract Introduction Material and Methods Results and Discussion Conclusion Remarks Acknowledgement References CHAPTER 3. COMBINATORIAL ENANTIOMERIC SEPARATION OF DIVERSE COMPOUNDS USING CAPILLARY ARRAY ELECTROPHORESIS Abstract Introduction Experimental Section Results and Discussion Conclusions Acknowledgement References CHAPTER 4. HIGH THROUGHPUT ANALYSIS OF TOTAL RNA EXPRESSION PROFILE BY CAPILLARY ELECTROPHORESIS 91 Abstract.... Introduction Experimental Section Results and Discussion Conclusions Acknowledgement References

Journal of Chromatography A, 2014

Tools capable of measuring binding affinities as well as amenable to downstream sequencing analys... more Tools capable of measuring binding affinities as well as amenable to downstream sequencing analysis are needed for study of DNA-protein interaction, particularly in discovery of new DNA sequences with affinity to diverse targets. Asymmetrical flow field-flow fractionation (AF4) is an open-channel separation technique that eliminates interference from column packing to the non-covalently bound complex and could potentially be applied for study of macromolecular interaction. The recovery and elution behaviors of the poly(dA) n strand and aptamers in AF4 were investigated. Good recovery of ssDNAs was achieved by judicious selection of the channel membrane with consideration of the membrane pore diameter and the radius of gyration (R g) of the ssDNA, which was obtained with the aid of a Molecular Dynamics tool. The R g values were also used to assess the folding situation of aptamers based on their migration times in AF4. The interactions between two ssDNA aptamers and their respective protein components were investigated. Using AF4, near-baseline resolution between the free and protein-bound aptamer fractions could be obtained. With this information, dissociation constants of ~16nM and ~57 nM were obtained for an IgE aptamer and a streptavidin aptamer, respectively. In addition, free and protein-bound IgE aptamer was extracted from the AF4 eluate and amplified, illustrating the potential of AF4 in screening ssDNAs with high affinity to targets. Our results demonstrate that AF4 is an effective tool holding several advantages over the existing techniques and should be useful for study of diverse macromolecular interaction systems.

The Analyst, 2014

Protein adsorption is sensitive enough to detect structural changes in the head group of the poly... more Protein adsorption is sensitive enough to detect structural changes in the head group of the polymeric ligand.