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Dive into the research topics where Ashton T. Ii Hamme is active.

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Featured researches published by Ashton T. Ii Hamme.


Bioconjugate Chemistry | 2015

Aptamer-conjugated graphene oxide membranes for highly efficient capture and accurate identification of multiple types of circulating tumor cells.

Bhanu Priya Viraka Nellore; Rajashekhar Kanchanapally; Avijit Pramanik; Sudarson Sekhar Sinha; Suhash Reddy Chavva; Ashton T. Ii Hamme; Paresh Chandra Ray

Tumor metastasis is responsible for 1 in 4 deaths in the United States. Though it has been well-documented over past two decades that circulating tumor cells (CTCs) in blood can be used as a biomarker for metastatic cancer, there are enormous challenges in capturing and identifying CTCs with sufficient sensitivity and specificity. Because of the heterogeneous expression of CTC markers, it is now well understood that a single CTC marker is insufficient to capture all CTCs from the blood. Driven by the clear need, this study reports for the first time highly efficient capture and accurate identification of multiple types of CTCs from infected blood using aptamer-modified porous graphene oxide membranes. The results demonstrate that dye-modified S6, A9, and YJ-1 aptamers attached to 20–40 μm porous garphene oxide membranes are capable of capturing multiple types of tumor cells (SKBR3 breast cancer cells, LNCaP prostate cancer cells, and SW-948 colon cancer cells) selectively and simultaneously from infected blood. Our result shows that the capture efficiency of graphene oxide membranes is ∼95% for multiple types of tumor cells; for each tumor concentration, 10 cells are present per milliliter of blood sample. The selectivity of our assay for capturing targeted tumor cells has been demonstrated using membranes without an antibody. Blood infected with different cells also has been used to demonstrate the targeted tumor cell capturing ability of aptamer-conjugated membranes. Our data also demonstrate that accurate analysis of multiple types of captured CTCs can be performed using multicolor fluorescence imaging. Aptamer-conjugated membranes reported here have good potential for the early diagnosis of diseases that are currently being detected by means of cell capture technologies.


ACS Applied Materials & Interfaces | 2015

Bio-Conjugated CNT-Bridged 3D Porous Graphene Oxide Membrane for Highly Efficient Disinfection of Pathogenic Bacteria and Removal of Toxic Metals from Water

Bhanu Priya Viraka Nellore; Rajashekhar Kanchanapally; Francisco Pedraza; Sudarson Sekhar Sinha; Avijit Pramanik; Ashton T. Ii Hamme; Zikri Arslan; Dhiraj K. Sardar; Paresh Chandra Ray

More than a billion people lack access to safe drinking water that is free from pathogenic bacteria and toxic metals. The World Health Organization estimates several million people, mostly children, die every year due to the lack of good quality water. Driven by this need, we report the development of PGLa antimicrobial peptide and glutathione conjugated carbon nanotube (CNT) bridged three-dimensional (3D) porous graphene oxide membrane, which can be used for highly efficient disinfection of Escherichia coli O157:H7 bacteria and removal of As(III), As(V), and Pb(II) from water. Reported results demonstrate that versatile membrane has the capability to capture and completely disinfect pathogenic pathogenic E. coli O157:H7 bacteria from water. Experimentally observed disinfection data indicate that the PGLa attached membrane can dramatically enhance the possibility of destroying pathogenic E. coli bacteria via synergistic mechanism. Reported results show that glutathione attached CNT-bridged 3D graphene oxide membrane can be used to remove As(III), As(V), and Pb(II) from water sample at 10 ppm level. Our data demonstrated that PGLa and glutathione attached membrane has the capability for high efficient removal of E. coli O157:H7 bacteria, As(III), As(V), and Pb(II) simultaneously from Mississippi River water.


Journal of Materials Chemistry B | 2015

Gold nanoparticle labeling based ICP-MS detection/measurement of bacteria, and their quantitative photothermal destruction

Yunfeng Lin; Ashton T. Ii Hamme

Bacteria such as Salmonella and E. coli present a great challenge in public health care in todays society. Protection of public safety against bacterial contamination and rapid diagnosis of infection require simple and fast assays for the detection and elimination of bacterial pathogens. After utilizing Salmonella DT104 as an example bacterial strain for our investigation, we report a rapid and sensitive assay for the qualitative and quantitative detection of bacteria by using antibody affinity binding, popcorn shaped gold nanoparticle (GNPOPs) labeling, surfance enchanced Raman spectroscopy (SERS), and inductively coupled plasma mass spectrometry (ICP-MS) detection. For qualitative analysis, our assay can detect Salmonella within 10 min by Raman spectroscopy; for quantitative analysis, our assay has the ability to measure as few as 100 Salmonella DT104 in a 1 mL sample (100 CFU/mL) within 40 min. Based on the quantitative detection, we investigated the quantitative destruction of Salmonella DT104, and the assays photothermal efficiency in order to reduce the amount of GNPOPs in the assay to ultimately to eliminate any potential side effects/toxicity to the surrounding cells in vivo. Results suggest that our assay may serve as a promising candidate for qualitative and quantitative detection and elimination of a variety of bacterial pathogens.


Analyst | 2014

Targeted highly sensitive detection/eradication of multi-drug resistant Salmonella DT104 through gold nanoparticle–SWCNT bioconjugated nanohybrids

Yunfeng Lin; Ashton T. Ii Hamme

Monoclonal antibody-conjugated sphere-shaped gold nanoparticles were combined with single-walled carbon nanotubes (SWCNTs) to create a nanohybrid system to selectively detect and eradicate multiple drug resistant Salmonella (MDRS) typhimurium DT104 bacteria. The Raman signal intensity from Rhodamine 6G (Rh6G) modified monoclonal AC04 antibody SWCNTs-gold nanoparticle (SWCNT-GNPs) hybrid provided a SERS enhancement by several orders of magnitude to detect the MDRS bacteria over the GNP system. A targeted photothermolysis experiment using 670 nm light at 2 W cm(-2) for 15 min, resulted in selective and irreparable damage to more than 99% Salmonella DT104 at the concentration of 10(5) CFU mL(-1). In comparison to solely SWCNTs or GNPs, our SWCNT-GNPs nanohybrids have also shown a better photothermal efficiency.


Heterocycles | 2005

Synthesis of functionalized 5,5-disubstituted isoxazolines via 1,3-dipolar cycloaddition reactions of geminal disubstituted alkenes

Ashton T. Ii Hamme; Jianping Xu; Jun Wang; Tiffany Cook; Erick D. Ellis

Regioselective syntheses of functionalized 5,5-disubstituted 2-isoxazolines were achieved through 1,3-dipolar cycloaddition reactions of various aromatic nitrile oxides with geminal disubstituted alkenes.


Tetrahedron Letters | 2017

Zinc mediated direct transformation of propargyl N-hydroxylamines to α,β-unsaturated ketones and mechanistic insight

Prasanta Das; Ashton T. Ii Hamme

A Lewis acid catalyzed direct transformation of propargyl N-hydroxylamines to α,β-unsaturated ketones in the presence of aqueous Zn(II)-salts has been described. This investigation also provides a novel observation for the stoichiometric role of Zn-halides over what is known to date for catalytic processes. A thorough mechanistic study has been established based on the experiment using 18O-labeled water in optimized reaction conditions; the incorporation of 18O in the desired product was also substantiated by HRMS. This methodology is also a mild, inexpensive, and an efficient approach for this unusual conversion.


Synthesis | 2006

Spiroisoxazoline Synthesis via Intramolecular Cyclization/Methylation

Jianping Xu; Jun Wang; Erick D. Ellis; Ashton T. Ii Hamme

The synthesis of regioisomeric spiroisoxazolines was achieved through an intramolecular cyclization/methylation reaction of a functionalized 5,5-disubstituted isoxazoline in one reaction vessel. The 5,5-isoxazoline was constructed through a 1,3-dipolar cycloaddition reaction of an aromatic nitrile oxide and a geminal disubstituted alkene.


Chemistry: A European Journal | 2013

Popcorn‐Shaped Magnetic Core–Plasmonic Shell Multifunctional Nanoparticles for the Targeted Magnetic Separation and Enrichment, Label‐Free SERS Imaging, and Photothermal Destruction of Multidrug‐Resistant Bacteria

Zhen Fan; Dulal Senapati; Sadia Afrin Khan; Anant Kumar Singh; Ashton T. Ii Hamme; Brian Yust; Dhiraj K. Sardar; Paresh Chandra Ray


Tetrahedron Letters | 2007

Isoxazoles from 1,1-disubstituted bromoalkenes

Sureshbabu Dadiboyena; Jianping Xu; Ashton T. Ii Hamme


Tetrahedron Letters | 2010

Synthesis of novel pyrazoles via [2+3]-dipolar cycloaddition using alkyne surrogates

Sureshbabu Dadiboyena; Edward J. Valente; Ashton T. Ii Hamme

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Jianping Xu

Jackson State University

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Paresh Chandra Ray

University of Texas at San Antonio

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Prasanta Das

Jackson State University

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Erick D. Ellis

Jackson State University

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