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Dr. Balaji Panchapakesan
Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA

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0 Carbon Nanotubes
0 Graphene
0 Nanocomposites
0 Transition Metal Dichalcogenides
0 Nanoelectromechanical systems

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Carbon Nanotubes
Graphene
Nanocomposites
Polymer actuators
Photo-thermal actuators

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Paper
Published: 15 June 2021 in Journal of Materials Chemistry C
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Pt-decorated phosphorene is a highly sensitive and selective sensor toward methanol gas molecules with a short recovery time.

ACS Style

Aref Aasi; Sadegh Mehdi Aghaei; Balaji Panchapakesan. Pt-decorated phosphorene as a propitious room temperature VOC gas sensor for sensitive and selective detection of alcohols. Journal of Materials Chemistry C 2021, 1 .

AMA Style

Aref Aasi, Sadegh Mehdi Aghaei, Balaji Panchapakesan. Pt-decorated phosphorene as a propitious room temperature VOC gas sensor for sensitive and selective detection of alcohols. Journal of Materials Chemistry C. 2021; ():1.

Chicago/Turabian Style

Aref Aasi; Sadegh Mehdi Aghaei; Balaji Panchapakesan. 2021. "Pt-decorated phosphorene as a propitious room temperature VOC gas sensor for sensitive and selective detection of alcohols." Journal of Materials Chemistry C , no. : 1.

Research article
Published: 05 February 2021 in ACS Omega
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In the present work, we report highly sensitive and selective nanosensors constructed with metal-decorated graphene-like BC6N employing nonequilibrium Green’s function (NEGF) formalism combined by density functional theory (DFT) toward multiple inorganic and sulfur-containing gas molecules (NO, NO2, NH3, CO, CO2, H2S, and SO2) as disease biomarkers from human breath. Monolayer sheets of pristine BC6N and Pd-decorated BC6N were evaluated for their gas adsorption properties, electronic property changes, sensitivity, and selectivity toward disease biomarkers. The pristine BC6N nanosheets exhibited sharp drops in the bandgap when interacted with gases such as NO2 while barely affected by other gases. However, the nanosecond recovery time and low adsorption energies limit the gas sensing applications of the pristine BC6N sheet. On the other hand, the Pd-decorated BC6N-based sensor underwent a semiconductor to metal transition upon the adsorption of NOx gas molecules. The conductance change of the sensor’s material in terms of I–V characteristics revealed that the Pd-decorated BC6N sensor is highly sensitive (98.6–134%) and selective (12.3–74.4 times) toward NOx gas molecules with a recovery time of 270 s under UV radiation at 498 K while weakly interacting with interfering gases in exhaled breath such as CO2 and H2O. The gas adsorption behavior suggests that metal-decorated BC6N sensors are excellent candidates for analyzing pulmonary disease and cardiovascular biomarkers, among other ailments of the stomach, kidney, and intestine.

ACS Style

Aref Aasi; Sadegh Mehdi Aghaei; Balaji Panchapakesan. Outstanding Performance of Transition-Metal-Decorated Single-Layer Graphene-like BC6N Nanosheets for Disease Biomarker Detection in Human Breath. ACS Omega 2021, 6, 4696 -4707.

AMA Style

Aref Aasi, Sadegh Mehdi Aghaei, Balaji Panchapakesan. Outstanding Performance of Transition-Metal-Decorated Single-Layer Graphene-like BC6N Nanosheets for Disease Biomarker Detection in Human Breath. ACS Omega. 2021; 6 (7):4696-4707.

Chicago/Turabian Style

Aref Aasi; Sadegh Mehdi Aghaei; Balaji Panchapakesan. 2021. "Outstanding Performance of Transition-Metal-Decorated Single-Layer Graphene-like BC6N Nanosheets for Disease Biomarker Detection in Human Breath." ACS Omega 6, no. 7: 4696-4707.

Mini review
Published: 20 January 2021 in ACS Omega
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MXenes, two-dimensional (2D) transition metal carbides and nitrides, have been arousing interest lately in the field of gas sensing thanks to their remarkable features such as graphene-like morphology, metal-comparable conductivity, large surface-to-volume ratio, mechanical flexibility, and great hydrophilic surface functionalities. With tunable etching and synthesis methods, the morphology of the MXenes, the interlayer structures, and functional group ratios on their surfaces were effectively harnessed, enhancing the efficiency of MXene-based gas-sensing devices. MXenes also efficiently form nanohybrids with other nanomaterials, as a practical approach to revamp the sensing performance of the MXene sensors. This Mini-Review summarizes the recent experimental and theoretical reports on the gas-sensing applications of MXenes and their hybrids. It also discusses the challenges and provides probable solutions that can accentuate the future perspective of MXenes in gas sensors.

ACS Style

Sadegh Mehdi Aghaei; Aref Aasi; Balaji Panchapakesan. Experimental and Theoretical Advances in MXene-Based Gas Sensors. ACS Omega 2021, 6, 2450 -2461.

AMA Style

Sadegh Mehdi Aghaei, Aref Aasi, Balaji Panchapakesan. Experimental and Theoretical Advances in MXene-Based Gas Sensors. ACS Omega. 2021; 6 (4):2450-2461.

Chicago/Turabian Style

Sadegh Mehdi Aghaei; Aref Aasi; Balaji Panchapakesan. 2021. "Experimental and Theoretical Advances in MXene-Based Gas Sensors." ACS Omega 6, no. 4: 2450-2461.

Journal article
Published: 08 September 2020 in Applied Surface Science
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In this work, we employ first-principles density functional theory calculations and nonequilibrium Green's function formalism to investigate the potential application of graphene-like borocarbonitride BC6N) for high-performance volatile organic compound (VOC) sensors used for human breath analysis. The adsorption behaviors of several VOCs (acetone, ethanol, methanol, formaldehyde, and toluene) and interfering gases in exhaled breath (carbon dioxide and water) are examined. The BC6N monolayer is a semiconductor with a bandgap of 1.228 eV. It is discovered that all the above gas molecules are physisorbed on the pristine BC6N sheet. The energy bandgap of pristine BC6N is slightly altered after interaction with the gas molecules. It is revealed that introducing a single carbon vacancy in the BC6N sheet can significantly increase the adsorption energies of the gas molecules. The modification of current-voltage responses due to VOC's disclose that the sensor shows high sensitivity, selectivity and short recovery for ethanol. Our results suggest that defective BC6N is a compelling and feasible candidate for chemiresistive sensors for applications in room temperature breath analysis of VOCs.

ACS Style

S.M. Aghaei; A. Aasi; Saman Farhangdoust; B. Panchapakesan. Graphene-like BC6N nanosheets are potential candidates for detection of volatile organic compounds (VOCs) in human breath: A DFT study. Applied Surface Science 2020, 536, 147756 .

AMA Style

S.M. Aghaei, A. Aasi, Saman Farhangdoust, B. Panchapakesan. Graphene-like BC6N nanosheets are potential candidates for detection of volatile organic compounds (VOCs) in human breath: A DFT study. Applied Surface Science. 2020; 536 ():147756.

Chicago/Turabian Style

S.M. Aghaei; A. Aasi; Saman Farhangdoust; B. Panchapakesan. 2020. "Graphene-like BC6N nanosheets are potential candidates for detection of volatile organic compounds (VOCs) in human breath: A DFT study." Applied Surface Science 536, no. : 147756.

Journal article
Published: 24 July 2020 in Nanotechnology
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In this study, single-wall carbon nanotubes (SWCNTs) decorated by platinum-group transition metals (Pt, Pd, Rh, or Ru) are introduced as promising nanosensors for the detection of toluene, an important biomarker in the exhaled breath of the lung cancer patients. First-principle calculations based on density functional theory (DFT) was employed to scrutinize the impact of an individual toluene gas molecule on the structural, electronic, and magnetic properties of pristine and metal decorated SWCNTs. It was discovered that toluene is physisorbed on the pristine SWCNT through the interaction of the π orbitals of the carbon atoms in the toluene and the nanotube. Decoration of the SWCNT with metal atoms enhanced the adsorption energies significantly by means of strong overlapping between d orbital of the metal atoms and p orbital of C atoms in the benzene ring of toluene. Investigations showed that toluene is strongly chemisorbed on Rh- and Ru-SWCNT systems via strong covalent bonds with the superior response (-96.98% and -99.98%, respectively), and moderately chemisorbed on Pt-SWCNTs (-27.3%) and Pd-SWCNTs (61.60%). Our findings propose the metal decorated SWCNT molecular sensors for the detection of toluene in the exhaled breath of the lung cancer patients and large-scale toluene removal from the environment.

ACS Style

Aref Aasi; Sadegh Mehdi Aghaei; Balaji Panchapakesan. A density functional theory study on the interaction of toluene with transition metal decorated carbon nanotubes: a promising platform for early detection of lung cancer from human breath. Nanotechnology 2020, 31, 415707 .

AMA Style

Aref Aasi, Sadegh Mehdi Aghaei, Balaji Panchapakesan. A density functional theory study on the interaction of toluene with transition metal decorated carbon nanotubes: a promising platform for early detection of lung cancer from human breath. Nanotechnology. 2020; 31 (41):415707.

Chicago/Turabian Style

Aref Aasi; Sadegh Mehdi Aghaei; Balaji Panchapakesan. 2020. "A density functional theory study on the interaction of toluene with transition metal decorated carbon nanotubes: a promising platform for early detection of lung cancer from human breath." Nanotechnology 31, no. 41: 415707.

Journal article
Published: 23 July 2020 in International Journal of Molecular Sciences
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As SARS-CoV-2 is spreading rapidly around the globe, adopting proper actions for confronting and protecting against this virus is an essential and unmet task. Reactive oxygen species (ROS) promoting molecules such as peroxides are detrimental to many viruses, including coronaviruses. In this paper, metal decorated single-wall carbon nanotubes (SWCNTs) were evaluated for hydrogen peroxide (H2O2) adsorption for potential use for designing viral inactivation surfaces. We employed first-principles methods based on the density functional theory (DFT) to investigate the capture of an individual H2O2 molecule on pristine and metal (Pt, Pd, Ni, Cu, Rh, or Ru) decorated SWCNTs. Although the single H2O2 molecule is weakly physisorbed on pristine SWCNT, a significant improvement on its adsorption energy was found by utilizing metal functionalized SWCNT as the adsorbent. It was revealed that Rh-SWCNT and Ru-SWCNT systems demonstrate outstanding performance for H2O2 adsorption. Furthermore, we discovered through calculations that Pt- and Cu-decorated SWNCT-H2O2 systems show high potential for filters for virus removal and inactivation with a very long shelf-life (2.2 × 1012 and 1.9 × 108 years, respectively). The strong adsorption of metal decorated SWCNTs and the long shelf-life of these nanomaterials suggest they are exceptional candidates for designing personal protection equipment against viruses.

ACS Style

Aref Aasi; Sadegh M Aghaei; Matthew D. Moore; Balaji Panchapakesan. Pt-, Rh-, Ru-, and Cu-Single-Wall Carbon Nanotubes Are Exceptional Candidates for Design of Anti-Viral Surfaces: A Theoretical Study. International Journal of Molecular Sciences 2020, 21, 5211 .

AMA Style

Aref Aasi, Sadegh M Aghaei, Matthew D. Moore, Balaji Panchapakesan. Pt-, Rh-, Ru-, and Cu-Single-Wall Carbon Nanotubes Are Exceptional Candidates for Design of Anti-Viral Surfaces: A Theoretical Study. International Journal of Molecular Sciences. 2020; 21 (15):5211.

Chicago/Turabian Style

Aref Aasi; Sadegh M Aghaei; Matthew D. Moore; Balaji Panchapakesan. 2020. "Pt-, Rh-, Ru-, and Cu-Single-Wall Carbon Nanotubes Are Exceptional Candidates for Design of Anti-Viral Surfaces: A Theoretical Study." International Journal of Molecular Sciences 21, no. 15: 5211.

Journals
Published: 03 May 2019 in Lab on a Chip
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We report the development of the nanotube-CTC-chip for isolation of circulating tumor cells of multiple phenotypes from peripheral blood.

ACS Style

Masoud S. Loeian; Sadegh Mehdi Aghaei; Farzaneh Farhadi; Veeresh Rai; Hong Wei Yang; Mark D. Johnson; Farrukh Aqil; Mounika Mandadi; Shesh N. Rai; Balaji Panchapakesan. Liquid biopsy using the nanotube-CTC-chip: capture of invasive CTCs with high purity using preferential adherence in breast cancer patients. Lab on a Chip 2019, 19, 1899 -1915.

AMA Style

Masoud S. Loeian, Sadegh Mehdi Aghaei, Farzaneh Farhadi, Veeresh Rai, Hong Wei Yang, Mark D. Johnson, Farrukh Aqil, Mounika Mandadi, Shesh N. Rai, Balaji Panchapakesan. Liquid biopsy using the nanotube-CTC-chip: capture of invasive CTCs with high purity using preferential adherence in breast cancer patients. Lab on a Chip. 2019; 19 (11):1899-1915.

Chicago/Turabian Style

Masoud S. Loeian; Sadegh Mehdi Aghaei; Farzaneh Farhadi; Veeresh Rai; Hong Wei Yang; Mark D. Johnson; Farrukh Aqil; Mounika Mandadi; Shesh N. Rai; Balaji Panchapakesan. 2019. "Liquid biopsy using the nanotube-CTC-chip: capture of invasive CTCs with high purity using preferential adherence in breast cancer patients." Lab on a Chip 19, no. 11: 1899-1915.

Publisher correction
Published: 06 March 2018 in Scientific Reports
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A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

ACS Style

Masoud S. Loeian; Dominika A. Ziolkowska; Farhad Khosravi; Jacek B. Jasinski; Balaji Panchapakesan. Publisher Correction: Exfoliated WS2-Nafion Composite based Electromechanical Actuators. Scientific Reports 2018, 8, 4296 .

AMA Style

Masoud S. Loeian, Dominika A. Ziolkowska, Farhad Khosravi, Jacek B. Jasinski, Balaji Panchapakesan. Publisher Correction: Exfoliated WS2-Nafion Composite based Electromechanical Actuators. Scientific Reports. 2018; 8 (1):4296.

Chicago/Turabian Style

Masoud S. Loeian; Dominika A. Ziolkowska; Farhad Khosravi; Jacek B. Jasinski; Balaji Panchapakesan. 2018. "Publisher Correction: Exfoliated WS2-Nafion Composite based Electromechanical Actuators." Scientific Reports 8, no. 1: 4296.

Journal article
Published: 08 January 2018 in Scientific Reports
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We describe the coupled straintronic-photothermic effect where coupling between bandgap of the 2D layered semiconductor under localized strains, optical absorption and the photo-thermal effect results in a large chromatic mechanical response in TMD-nanocomposites. Under the irradiation of visible light (405 nm to 808 nm), such locally strained atomic thin films based on 2H-MoS2 embedded in an elastomer such as poly (dimethyl) siloxane matrix exhibited a large amplitude of photo-thermal actuation compared to their unstrained counterparts. Moreover, the locally strain engineered nanocomposites showed tunable mechanical response giving rise to higher mechanical stress at lower photon energies. Scanning photoluminescence spectroscopy revealed a change in bandgap of 30 meV between regions encompassing highly strained compared to the unstrained few layers. For 1.6% change in the bandgap, the macroscopic photo-thermal response increased by a factor of two. Millimeter scale bending actuators based on the locally strained 2H-MoS2 resulted in significantly enhanced photo-thermal actuation displacements compared to their unstrained counterparts at lower photon energies and operated up to 30 Hz. Almost 1 mN photo-activated force was obtained at 50 mW and provided long-term stability. This study demonstrates a new mechanism in TMD-nanocomposites that would be useful for developing broad range of transducers.

ACS Style

Vahid Rahneshin; Dominika A. Ziolkowska; Arthur McClelland; Jaya Cromwell; Jacek B. Jasinski; Balaji Panchapakesan. The Coupled Straintronic-Photothermic Effect. Scientific Reports 2018, 8, 64 .

AMA Style

Vahid Rahneshin, Dominika A. Ziolkowska, Arthur McClelland, Jaya Cromwell, Jacek B. Jasinski, Balaji Panchapakesan. The Coupled Straintronic-Photothermic Effect. Scientific Reports. 2018; 8 (1):64.

Chicago/Turabian Style

Vahid Rahneshin; Dominika A. Ziolkowska; Arthur McClelland; Jaya Cromwell; Jacek B. Jasinski; Balaji Panchapakesan. 2018. "The Coupled Straintronic-Photothermic Effect." Scientific Reports 8, no. 1: 64.

Publisher correction
Published: 05 January 2018 in Scientific Reports
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A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

ACS Style

Masoud S. Loeian; Dominika A. Ziolkowska; Farhad Khosravi; Jacek B. Jasinski; Balaji Panchapakesan. Publisher Correction: Exfoliated WS2-Nafion Composite based Electromechanical Actuators. Scientific Reports 2018, 8, 275 .

AMA Style

Masoud S. Loeian, Dominika A. Ziolkowska, Farhad Khosravi, Jacek B. Jasinski, Balaji Panchapakesan. Publisher Correction: Exfoliated WS2-Nafion Composite based Electromechanical Actuators. Scientific Reports. 2018; 8 (1):275.

Chicago/Turabian Style

Masoud S. Loeian; Dominika A. Ziolkowska; Farhad Khosravi; Jacek B. Jasinski; Balaji Panchapakesan. 2018. "Publisher Correction: Exfoliated WS2-Nafion Composite based Electromechanical Actuators." Scientific Reports 8, no. 1: 275.

Journal article
Published: 03 November 2017 in Scientific Reports
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The ability to convert electrical energy into mechanical motion is of significant interest in many energy conversion technologies. Here, we demonstrate the first liquid phase exfoliated WS2-Nafion nanocomposite based electro-mechanical actuators. Highly exfoliated layers of WS2 mixed with Nafion solution, solution cast and doped with Li+ was studied as electromechanical actuators. Resonant Raman spectroscopy, X-ray photo-electron-spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and AC impedance spectroscopy were used to study the structure, photoluminescence, water uptake, mechanical and electromechanical actuation properties of the exfoliated nanocomposites. A 114% increase in elastic modulus (dry condition), 160% increase in proton conductivity, 300% increase in water uptake, cyclic strain amplitudes of ~0.15% for 0.1 Hz excitation frequency, tip displacements greater than nanotube-Nafion and graphene-Nafion actuators and continuous operation for more than 5 hours is observed for TMD-Nafion actuators. The mechanism behind the increase in water uptake is a result of oxygen atoms occupying the vacancies in the hydrophilic exfoliated flakes and subsequently bonding with water, not possible in Nafion composites based on carbon nanotube and graphene.

ACS Style

Masoud S. Loeian; Dominika A. Ziolkowska; Farhad Khosravi; Jacek B. Jasinski; Balaji Panchapakesan. Exfoliated WS2-Nafion Composite based Electromechanical Actuators. Scientific Reports 2017, 7, 14599 .

AMA Style

Masoud S. Loeian, Dominika A. Ziolkowska, Farhad Khosravi, Jacek B. Jasinski, Balaji Panchapakesan. Exfoliated WS2-Nafion Composite based Electromechanical Actuators. Scientific Reports. 2017; 7 (1):14599.

Chicago/Turabian Style

Masoud S. Loeian; Dominika A. Ziolkowska; Farhad Khosravi; Jacek B. Jasinski; Balaji Panchapakesan. 2017. "Exfoliated WS2-Nafion Composite based Electromechanical Actuators." Scientific Reports 7, no. 1: 14599.

Proceedings article
Published: 31 August 2017 in Nanoengineering: Fabrication, Properties, Optics, and Devices XIV
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ACS Style

Balaji Panchapakesan; Vahid Rahneshin. Chromatic photo-thermal actuators based on 2H-MoS2 based nanocomposites. Nanoengineering: Fabrication, Properties, Optics, and Devices XIV 2017, 29 .

AMA Style

Balaji Panchapakesan, Vahid Rahneshin. Chromatic photo-thermal actuators based on 2H-MoS2 based nanocomposites. Nanoengineering: Fabrication, Properties, Optics, and Devices XIV. 2017; ():29.

Chicago/Turabian Style

Balaji Panchapakesan; Vahid Rahneshin. 2017. "Chromatic photo-thermal actuators based on 2H-MoS2 based nanocomposites." Nanoengineering: Fabrication, Properties, Optics, and Devices XIV , no. : 29.

Conference paper
Published: 29 August 2017 in Biosensing and Nanomedicine X
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We present a new method for circulating tumor cell capture based on micro-array isolation from droplets. Called droplet biopsy, our technique uses a 76-element array of carbon nanotube devices functionalized with anti-EpCAM and antiHer2 antibodies for immunocapture of spiked breast cancer cells in the blood. This droplet biopsy chip can enable capture of CTCs based on both positive and negative selection strategy. Negative selection is achieved through depletion of contaminating leukocytes through the differential settling of blood into layers. We report 55%-100% cancer cell capture yield in this first droplet biopsy chip study. The droplet biopsy is an enabling idea where one can capture CTCs based on multiple biomarkers in a single blood sample.

ACS Style

Balaji Panchapakesan. Micro-array isolation of circulating tumor cells (CTCs): the droplet biopsy chip. Biosensing and Nanomedicine X 2017, 10352, 103520G .

AMA Style

Balaji Panchapakesan. Micro-array isolation of circulating tumor cells (CTCs): the droplet biopsy chip. Biosensing and Nanomedicine X. 2017; 10352 ():103520G.

Chicago/Turabian Style

Balaji Panchapakesan. 2017. "Micro-array isolation of circulating tumor cells (CTCs): the droplet biopsy chip." Biosensing and Nanomedicine X 10352, no. : 103520G.

Book chapter
Published: 02 June 2017 in Photomechanical Materials, Composites, and Systems
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ACS Style

Balaji Panchapakesan; Farhad Khosravi; James Loomis; Eugene M. Terentjev. Photomechanical Effects in Polymer Nanocomposites. Photomechanical Materials, Composites, and Systems 2017, 179 -231.

AMA Style

Balaji Panchapakesan, Farhad Khosravi, James Loomis, Eugene M. Terentjev. Photomechanical Effects in Polymer Nanocomposites. Photomechanical Materials, Composites, and Systems. 2017; ():179-231.

Chicago/Turabian Style

Balaji Panchapakesan; Farhad Khosravi; James Loomis; Eugene M. Terentjev. 2017. "Photomechanical Effects in Polymer Nanocomposites." Photomechanical Materials, Composites, and Systems , no. : 179-231.

Journal article
Published: 17 April 2017 in Biosensors
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This study demonstrates the rapid and label-free detection of Interleukin-6 (IL-6) using carbon nanotube micro-arrays with aptamer as the molecular recognition element. Single wall carbon nanotubes micro-arrays biosensors were manufactured using photo-lithography, metal deposition, and etching techniques. Nanotube biosensors were functionalized with 1-Pyrenebutanoic Acid Succinimidyl Ester (PASE) conjugated IL-6 aptamers. Real time response of the sensor conductance was monitored with increasing concentration of IL-6 (1 pg/mL to 10 ng/mL), exposure to the sensing surface in buffer solution, and clinically relevant spiked blood samples. Non-specific Bovine Serum Albumin (BSA), PBS samples, and anti-IgG functionalized devices gave similar signatures in the real time conductance versus time experiments with no significant change in sensor signal. Exposure of the aptamer functionalized nanotube surface to IL-6 decreased the conductance with increasing concentration of IL-6. Experiments based on field effect transistor arrays suggested shift in drain current versus gate voltage for 1 pg and 1 ng of IL-6 exposure. Non-specific BSA did not produce any appreciable shift in the Ids versus Vg suggesting specific interactions of IL-6 on PASE conjugated aptamer surface gave rise to the change in electrical signal. Both Z axis and phase image in an Atomic Force Microscope (AFM) suggested unambiguous molecular interaction of the IL-6 on the nanotube-aptamer surface at 1 pg/mL concentration. The concentration of 1 pg falls below the diagnostic gray zone for cancer (2.3 pg-4 ng/mL), which is an indicator of early stage cancer. Thus, nanotube micro-arrays could potentially be developed for creating multiplexed assays involving cancer biomarker proteins and possibly circulating tumor cells all in a single assay using PASE functionalization protocol.

ACS Style

Farhad Khosravi; Seyed Masoud Loeian; Balaji Panchapakesan. Ultrasensitive Label-Free Sensing of IL-6 Based on PASE Functionalized Carbon Nanotube Micro-Arrays with RNA-Aptamers as Molecular Recognition Elements. Biosensors 2017, 7, 17 .

AMA Style

Farhad Khosravi, Seyed Masoud Loeian, Balaji Panchapakesan. Ultrasensitive Label-Free Sensing of IL-6 Based on PASE Functionalized Carbon Nanotube Micro-Arrays with RNA-Aptamers as Molecular Recognition Elements. Biosensors. 2017; 7 (4):17.

Chicago/Turabian Style

Farhad Khosravi; Seyed Masoud Loeian; Balaji Panchapakesan. 2017. "Ultrasensitive Label-Free Sensing of IL-6 Based on PASE Functionalized Carbon Nanotube Micro-Arrays with RNA-Aptamers as Molecular Recognition Elements." Biosensors 7, no. 4: 17.

Journal article
Published: 07 October 2016 in Scientific Reports
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The ability to convert photons of different wavelengths directly into mechanical motion is of significant interest in many energy conversion and reconfigurable technologies. Here, using few layer 2H-MoS2 nanosheets, layer by layer process of nanocomposite fabrication, and strain engineering, we demonstrate a reversible and chromatic mechanical response in MoS2-nanocomposites between 405 nm to 808 nm with large stress release. The chromatic mechanical response originates from the d orbitals and is related to the strength of the direct exciton resonance A and B of the few layer 2H-MoS2 affecting optical absorption and subsequent mechanical response of the nanocomposite. Applying uniaxial tensile strains to the semiconducting few-layer 2H-MoS2 crystals in the nanocomposite resulted in spatially varying energy levels inside the nanocomposite that enhanced the broadband optical absorption up to 2.3 eV and subsequent mechanical response. The unique photomechanical response in 2H-MoS2 based nanocomposites is a result of the rich d electron physics not available to nanocomposites based on sp bonded graphene and carbon nanotubes, as well as nanocomposite based on metallic nanoparticles. The reversible strain dependent optical absorption suggest applications in broad range of energy conversion technologies that is not achievable using conventional thin film semiconductors.

ACS Style

Vahid Rahneshin; Farhad Khosravi; Dominika A. Ziolkowska; Jacek B. Jasinski; Balaji Panchapakesan. Chromatic Mechanical Response in 2-D Layered Transition Metal Dichalcogenide (TMDs) based Nanocomposites. Scientific Reports 2016, 6, 34831 .

AMA Style

Vahid Rahneshin, Farhad Khosravi, Dominika A. Ziolkowska, Jacek B. Jasinski, Balaji Panchapakesan. Chromatic Mechanical Response in 2-D Layered Transition Metal Dichalcogenide (TMDs) based Nanocomposites. Scientific Reports. 2016; 6 (1):34831.

Chicago/Turabian Style

Vahid Rahneshin; Farhad Khosravi; Dominika A. Ziolkowska; Jacek B. Jasinski; Balaji Panchapakesan. 2016. "Chromatic Mechanical Response in 2-D Layered Transition Metal Dichalcogenide (TMDs) based Nanocomposites." Scientific Reports 6, no. 1: 34831.

Journal article
Published: 29 September 2016 in Nanotechnology
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We demonstrate the rapid and label-free capture of breast cancer cells spiked in blood using nanotube-antibody micro-arrays. 76-element single wall carbon nanotube arrays were manufactured using photo-lithography, metal deposition, and etching techniques. Anti-epithelial cell adhesion molecule (anti-EpCAM), Anti-human epithelial growth factor receptor 2 (anti-Her2) and non-specific IgG antibodies were functionalized to the surface of the nanotube devices using 1-pyrene-butanoic acid succinimidyl ester. Following device functionalization, blood spiked with SKBR3, MCF7 and MCF10A cells (100/1000 cells per 5 µl per device, 170 elements totaling 0.85 ml of whole blood) were adsorbed on to the nanotube device arrays. Electrical signatures were recorded from each device to screen the samples for differences in interaction (specific or non-specific) between samples and devices. A zone classification scheme enabled the classification of all 170 elements in a single map. A kernel-based statistical classifier for the ‘liquid biopsy’ was developed to create a predictive model based on dynamic time warping series (DTW) to classify device electrical signals that corresponded to plain blood (control) or SKBR3 spiked blood (case) on anti-Her2 functionalized devices with ~90% sensitivity, and 90% specificity in capture of 1000 SKBR3 breast cancer cells in blood using anti-Her2 functionalized devices. Screened devices that gave positive electrical signatures were confirmed using optical/confocal microscopy to hold spiked cancer cells. Confocal microscopic analysis of devices that were classified to hold spiked blood based on their electrical signatures confirmed the presence of cancer cells through staining for DAPI (nuclei), cytokeratin (cancer cells) and CD45 (hematologic cells) with single cell sensitivity. We report 55–100% cancer cell capture yield depending on the active device area for blood adsorption with mean of 62% (~12,500 captured off 20,000 spiked cells in 0.1 ml blood) in this first nanotube-CTC chip study.

ACS Style

Farhad Khosravi; Patrick Trainor; Christopher Lambert; Goetz Kloecker; Eric Wickstrom; Shesh N Rai; Balaji Panchapakesan. Static micro-array isolation, dynamic time series classification, capture and enumeration of spiked breast cancer cells in blood: the nanotube–CTC chip. Nanotechnology 2016, 27, 44LT03 -44LT03.

AMA Style

Farhad Khosravi, Patrick Trainor, Christopher Lambert, Goetz Kloecker, Eric Wickstrom, Shesh N Rai, Balaji Panchapakesan. Static micro-array isolation, dynamic time series classification, capture and enumeration of spiked breast cancer cells in blood: the nanotube–CTC chip. Nanotechnology. 2016; 27 (44):44LT03-44LT03.

Chicago/Turabian Style

Farhad Khosravi; Patrick Trainor; Christopher Lambert; Goetz Kloecker; Eric Wickstrom; Shesh N Rai; Balaji Panchapakesan. 2016. "Static micro-array isolation, dynamic time series classification, capture and enumeration of spiked breast cancer cells in blood: the nanotube–CTC chip." Nanotechnology 27, no. 44: 44LT03-44LT03.

Journal article
Published: 22 September 2016 in Actuators
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In this paper, we have developed a new thermoacoustic model for predicting the resonance frequency and quality factors of one-dimensional (1D) nanoresonators. Considering a nanoresonator as a fix-free Bernoulli-Euler cantilever, an analytical model has been developed to show the influence of material and geometrical properties of 1D nanoresonators on their mechanical response without any damping. Diameter and elastic modulus have a direct relationship and length has an inverse relationship on the strain energy and stress at the clamp end of the nanoresonator. A thermoacoustic multiphysics COMSOL model has been elaborated to simulate the frequency response of vibrating 1D nanoresonators in air. The results are an excellent match with experimental data from independently published literature reports, and the results of this model are consistent with the analytical model. Considering the air and thermal damping in the thermoacoustic model, the quality factor of a nanowire has been estimated and the results show that zinc oxide (ZnO) and silver-gallium (Ag2Ga) nanoresonators are potential candidates as nanoresonators, nanoactuators, and for scanning probe microscopy applications.

ACS Style

Masoud S. Loeian; Robert W. Cohn; Balaji Panchapakesan. A Thermoacoustic Model for High Aspect Ratio Nanostructures. Actuators 2016, 5, 23 .

AMA Style

Masoud S. Loeian, Robert W. Cohn, Balaji Panchapakesan. A Thermoacoustic Model for High Aspect Ratio Nanostructures. Actuators. 2016; 5 (4):23.

Chicago/Turabian Style

Masoud S. Loeian; Robert W. Cohn; Balaji Panchapakesan. 2016. "A Thermoacoustic Model for High Aspect Ratio Nanostructures." Actuators 5, no. 4: 23.

Journal article
Published: 02 June 2016 in Actuators
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Recently various nanomaterials, such as carbon nanotubes and graphene, have been added to rubbery elastomers, such as poly dimethyl siloxane (PDMS), to enable generation of stress and displacement in response to remote illumination. While the response is primarily due to heat-induced generation of stress; i.e., the thermoelastic effect in rubbers, illuminated samples have shown unexpected deviations between the transient waveforms of sample temperature and induced stress. In this report we have created a new and simple lumped element model to explain the stress behavior of these photomechanical nanocomposites. The model consists of two parameters that describe the spatially averaged steady state temperature rise due to optical absorption of the structure (typically a long strip of pre-strained elastomer) and the spatially averaged convective cooling rate of the strip, together with a time-varying function that effectively represents the temperature distribution and thermal convection along the length of the strip. The model is used to compare two actuators that each have a thin embedded layer of carbon nanotubes, in which the one film consists of randomly aligned nanotubes and the other has a much more ordered alignment. The model not only fits both transient responses, but the differences between the parameters suggests that the ordered film conducts heat across the strip more rapidly than the disordered film, leading to it more rapidly reaching the steady state level of maximum stress. This model should be helpful in future experimental studies that work to observe, delineate and identify possible nanoscale and molecular contributions to photomechanical stress.

ACS Style

Robert W. Cohn; Balaji Panchapakesan. Spatially Nonuniform Heating and the Nonlinear Transient Response of Elastomeric Photomechanical Actuators. Actuators 2016, 5, 16 .

AMA Style

Robert W. Cohn, Balaji Panchapakesan. Spatially Nonuniform Heating and the Nonlinear Transient Response of Elastomeric Photomechanical Actuators. Actuators. 2016; 5 (2):16.

Chicago/Turabian Style

Robert W. Cohn; Balaji Panchapakesan. 2016. "Spatially Nonuniform Heating and the Nonlinear Transient Response of Elastomeric Photomechanical Actuators." Actuators 5, no. 2: 16.

Methodology
Published: 01 June 2016 in Open Access Medical Statistics
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Classification of biosensor time series using dynamic time warping: applications in screening cancer cells with characteristic biomarkers Shesh N Rai,1,2* Patrick J Trainor,2,3* Farhad Khosravi,4 Goetz Kloecker,5 Balaji Panchapakesan4 1Biostatistics Shared Facility, JG Brown Cancer Center, University of Louisville, 2Department of Bioinformatics and Biostatistics, University of Louisville, 3Department of Medicine, University of Louisville, KY, USA; 4Small Systems Laboratory, Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA, 5Hematology and Oncology, James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA *These authors contributed equally to this work. The development of biosensors that produce time series data will facilitate improvements in biomedical diagnostics and in personalized medicine. The time series produced by these devices often contains characteristic features arising from biochemical interactions between the sample and the sensor. To use such characteristic features for determining sample class, similarity-based classifiers can be utilized. However, the construction of such classifiers is complicated by the variability in the time domains of such series that renders the traditional distance metrics such as Euclidean distance ineffective in distinguishing between biological variance and time domain variance. The dynamic time warping (DTW) algorithm is a sequence alignment algorithm that can be used to align two or more series to facilitate quantifying similarity. In this article, we evaluated the performance of DTW distance-based similarity classifiers for classifying time series that mimics electrical signals produced by nanotube biosensors. Simulation studies demonstrated the positive performance of such classifiers in discriminating between time series containing characteristic features that are obscured by noise in the intensity and time domains. We then applied a DTW distance-based k-nearest neighbors classifier to distinguish the presence/absence of mesenchymal biomarker in cancer cells in buffy coats in a blinded test. Using a train–test approach, we find that the classifier had high sensitivity (90.9%) and specificity (81.8%) in differentiating between EpCAM-positive MCF7 cells spiked in buffy coats and those in plain buffy coats. Keywords: buffy coats, cancer detection, breast cancer, epcam, MCF7, k-nn classifier, biosensors, time series, instance-based learning

ACS Style

Balaji Panchapakesan; Patrick Trainor; Shesh N Rai; Farhad Khosravi; Goetz Kloecker. Classification of biosensor time series using dynamic time warping: applications in screening cancer cells with characteristic biomarkers. Open Access Medical Statistics 2016, 6, 21 -29.

AMA Style

Balaji Panchapakesan, Patrick Trainor, Shesh N Rai, Farhad Khosravi, Goetz Kloecker. Classification of biosensor time series using dynamic time warping: applications in screening cancer cells with characteristic biomarkers. Open Access Medical Statistics. 2016; 6 (6):21-29.

Chicago/Turabian Style

Balaji Panchapakesan; Patrick Trainor; Shesh N Rai; Farhad Khosravi; Goetz Kloecker. 2016. "Classification of biosensor time series using dynamic time warping: applications in screening cancer cells with characteristic biomarkers." Open Access Medical Statistics 6, no. 6: 21-29.