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Silva MP, Rodrigues CG, Machado DC, Nogueira RA. Long-term memory in Staphylococcus aureus α-hemolysin ion channel kinetics. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:661-671. [PMID: 37542583 DOI: 10.1007/s00249-023-01675-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/03/2023] [Accepted: 07/20/2023] [Indexed: 08/07/2023]
Abstract
The kinetics of an ion channel are classically understood as a random process. However, studies have shown that in complex ion channels, formed by multiple subunits, this process can be deterministic, presenting long-term memory. Staphylococcus aureus α-hemolysin (α-HL) is a toxin that acts as the major factor in Staphylococcus aureus virulence. α-HL is a water-soluble protein capable of forming ion channels into lipid bilayers, by insertion of an amphipathic β-barrel. Here, the α-HL was used as an experimental model to study memory in ion channel kinetics. We applied the approximate entropy (ApEn) approach to analyze randomness and the Detrended Fluctuation Analysis (DFA) to investigate the existence of long memory in α-HL channel kinetics. Single-channel currents were measured through experiments with α-HL channels incorporated in planar lipid bilayers. All experiments were carried out under the following conditions: 1 M NaCl solution, pH 4.5; transmembrane potential of + 40 mV and temperature 25 ± 1 °C. Single-channel currents were recorded in real-time in the memory of a microcomputer coupled to an A/D converter and a patch-clamp amplifier. The conductance value of the α-HL channels was 0.82 ± 0.0025 nS (n = 128). The DFA analysis showed that the kinetics of α-HL channels presents long-term memory ([Formula: see text] = 0.63 ± 0.04). The ApEn outcomes showed low complexity to dwell times when open (ApEno = 0.5514 ± 0.28) and closed (ApEnc = 0.1145 ± 0.08), corroborating the results of the DFA method.
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Affiliation(s)
- M P Silva
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil
| | - C G Rodrigues
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Recife, Pernambuco, Brazil
| | - D C Machado
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Recife, Pernambuco, Brazil
| | - R A Nogueira
- Department of Animal Morphology and Physiology, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil.
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da Silva AAR, da Silva Júnior JJ, Cavalcanti MIDS, Machado DC, Medeiros PL, Rodrigues CG. Alphatoxin Nanopore Detection of Aflatoxin, Ochratoxin and Fumonisin in Aqueous Solution. Toxins (Basel) 2023; 15:toxins15030183. [PMID: 36977074 PMCID: PMC10058818 DOI: 10.3390/toxins15030183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/23/2023] [Accepted: 02/26/2023] [Indexed: 03/08/2023] Open
Abstract
Mycotoxins are toxic and carcinogenic metabolites produced by groups of filamentous fungi that colonize food crops. Aflatoxin B1 (AFB1), ochratoxin A (OTA) and fumonisin B1 (FB1) are among the most relevant agricultural mycotoxins, as they can induce various toxic processes in humans and animals. To detect AFB1, OTA and FB1 in the most varied matrices, chromatographic and immunological methods are primarily used; however, these techniques are time-consuming and expensive. In this study, we demonstrate that unitary alphatoxin nanopore can be used to detect and differentiate these mycotoxins in aqueous solution. The presence of AFB1, OTA or FB1 inside the nanopore induces reversible blockage of the ionic current flowing through the nanopore, with distinct characteristics of blockage that are unique to each of the three toxins. The process of discrimination is based on the residual current ratio calculation and analysis of the residence time of each mycotoxin inside the unitary nanopore. Using a single alphatoxin nanopore, the mycotoxins could be detected at the nanomolar level, indicating that alphatoxin nanopore is a promising molecular tool for discriminatory analysis of mycotoxins in aqueous solution.
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Affiliation(s)
- Artur Alves Rodrigues da Silva
- Education and Health Center, Federal University of Campina Grande, Rua Aprígio Veloso, 882, Universitário, Campina Grande 58429-900, Brazil
- Postgraduate Program in Therapeutic Innovation, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
| | - Janilson José da Silva Júnior
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
| | - Maria Isabel dos Santos Cavalcanti
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
| | - Dijanah Cota Machado
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
| | - Paloma Lys Medeiros
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
| | - Claudio Gabriel Rodrigues
- Postgraduate Program in Therapeutic Innovation, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
- Department of Biophysics and Radiobiology, Federal University of Pernambuco, Avenida Professor Moraes Rego, s/n, Cidade Universitária, Recife 50670-901, Brazil
- Correspondence: ; Tel.: +55-81-2126-8535
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Li L, Zhou F, Xue Q. Conductive polymer hydrogel-coated nanopipette sensor with tunable size. NANOTECHNOLOGY AND PRECISION ENGINEERING 2022. [DOI: 10.1063/10.0016501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nanopipette-based sensors are one of the most effective tools for detecting nanoparticles, bioparticles, and biomolecules. Quantitative analysis of nanoparticles with different shapes and electrical charges is achieved through measurement of the blockage currents that occur when particles pass through the nanopore. However, typical nanopipette sensors fabricated using a conventional needle-pulling method have a typical pore-diameter limitation of around 100 nm. Herein, we report a novel conductive hydrogel-composited nanopipette sensor with a tunable inner-pore diameter. This is made by electrodepositing poly(3,4-ethylenedioxythiophene) polystyrene sulfonate onto the surface of a nanopipette with a prefabricated sacrificial copper layer. Because of the presence of copper ions, the conductive polymer can stably adhere to the tip of the nanopipette to form a nanopore; when nanoparticles pass through the conductive nanopore, more distinct blocking events are observed. The size of the nanopore can be changed simply by adjusting the electrodeposition time. In this way, suitable nanopores can be obtained for highly sensitive screening of a series of particles with diameters of the order of tens of nanometers.
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Affiliation(s)
- Lin Li
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Feng Zhou
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
| | - Qiannan Xue
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China
- College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China
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Bhatti H, Jawed R, Ali I, Iqbal K, Han Y, Lu Z, Liu Q. Recent advances in biological nanopores for nanopore sequencing, sensing and comparison of functional variations in MspA mutants. RSC Adv 2021; 11:28996-29014. [PMID: 35478559 PMCID: PMC9038099 DOI: 10.1039/d1ra02364k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 08/09/2021] [Indexed: 12/14/2022] Open
Abstract
Biological nanopores are revolutionizing human health by the great myriad of detection and diagnostic skills. Their nano-confined area and ingenious shape are suitable to investigate a diverse range of molecules that were difficult to identify with the previous techniques. Additionally, high throughput and label-free detection of target analytes instigated the exploration of new bacterial channel proteins such as Fragaceatoxin C (FraC), Cytolysin A (ClyA), Ferric hydroxamate uptake component A (FhuA) and Curli specific gene G (CsgG) along with the former ones, like α-hemolysin (αHL), Mycobacterium smegmatis porin A (MspA), aerolysin, bacteriophage phi 29 and Outer membrane porin G (OmpG). Herein, we discuss some well-known biological nanopores but emphasize on MspA and compare the effects of site-directed mutagenesis on the detection ability of its mutants in view of the surface charge distribution, voltage threshold and pore-analyte interaction. We also discuss illustrious and latest advances in biological nanopores for past 2-3 years due to limited space. Last but not the least, we elucidate our perspective for selecting a biological nanopore and propose some future directions to design a customized nanopore that would be suitable for DNA sequencing and sensing of other nontrivial molecules in question.
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Affiliation(s)
- Huma Bhatti
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China +86-25-83793283 +86-25-83793283
| | - Rohil Jawed
- School of Life Science and Technology, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China
| | - Irshad Ali
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China +86-25-83793283 +86-25-83793283
| | - Khurshid Iqbal
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China +86-25-83793283 +86-25-83793283
| | - Yan Han
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China +86-25-83793283 +86-25-83793283
| | - Zuhong Lu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China +86-25-83793283 +86-25-83793283
| | - Quanjun Liu
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University No. 2 Sipailou Nanjing 210096 People's Republic of China +86-25-83793283 +86-25-83793283
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Sen P, Hoi H, Gupta M. Low Noise Hybrid Nanopore with Engineered OmpG and Bilayer MoS 2. ACS APPLIED BIO MATERIALS 2021; 4:5416-5424. [DOI: 10.1021/acsabm.1c00095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Payel Sen
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton Alberta, Canada
| | - Hiofan Hoi
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton Alberta, Canada
| | - Manisha Gupta
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton Alberta, Canada
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