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Lai Y, Jiang G, Liang T, Huang X, Jiang W, Xu W, Sun R, Dai Z, Li C. Rapid analysis of Bacillus cereus spore biomarkers based on porous channel cuttlebone SERS substrate. Anal Chim Acta 2024; 1320:343034. [PMID: 39142776 DOI: 10.1016/j.aca.2024.343034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 07/13/2024] [Accepted: 07/26/2024] [Indexed: 08/16/2024]
Abstract
BACKGROUND Bacillus cereus (B. cereus) is a widespread conditional pathogen that affects food safety and human health. Conventional methods such as bacteria culture and polymerase chain reaction (PCR) are difficult to use for rapid identification of bacterial spores because of the relatively long analysis times. From a human health perspective, there is an urgent need to develop an ultrasensitive, rapid, and accurate method for the detection of B. cereus spores. RESULTS The study proposed a new method for rapidly and sensitively detecting the biomarkers of bacterial spores via surface-enhanced Raman spectroscopy (SERS) combined with electrochemical enrichment. The 2,6-Pyridinedicarboxylic acid (DPA) was used as the model analyte to acts as a biomarker of B. cereus spores. The SERS substrate was developed via the in-situ generation of Ag nanoparticles (AgNPs) in a cuttlebone-derived organic matrix (CDOM). Because of the depletion of chitin reduction sites on the CDOM, the pores of the porous channels expanded. The pores diameter of the AgNPs/CDOM porous channel was found to be in the range of 0.7-1.3 nm through molecular diffusion experiments. Based on the porosity of AgNPs/CDOM substrates and the high sensitivity of SERS substrates, the sensor can rapidly and accurately electronically enrich DPA in 40 s with the limit of detection (LOD) of 0.3 nM. SIGNIFICANCE The results demonstrate that electrochemically assisted SERS substrates can be served as a high sensitivity electrochemical-enrichment device for the rapid and sensitive detection of bacterial spores with minimal interference from potentially coexisting species in biological samples. In this study, it opens up a platform to explore the application of porous channels in natural bio-derived materials in the field of food safety.
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Affiliation(s)
- Yuping Lai
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China
| | - Guangzheng Jiang
- Guangxi Engineering Research Center of Processing & Storage of Characteristic and Advantage Aquatic Products, Guangxi Academy of Fishery Sciences, Nanning, 530021, China
| | - Tianhang Liang
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China
| | - Xiaoxin Huang
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China
| | - Wanjun Jiang
- The North China Sea Area & Island Center, Ministry of Natural Resources, Qingdao, 266061, China.
| | - Wenhui Xu
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China
| | - Ruikun Sun
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China; Shenzhen Institute of Guangdong Ocean University, Shenzhen, 518108, China
| | - Zhenqing Dai
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China; Shenzhen Institute of Guangdong Ocean University, Shenzhen, 518108, China.
| | - Chengyong Li
- School of Chemistry and Environment, Guangdong Ocean University, Analytical and Testing Center of Guangdong Ocean University, Guangdong Provincial Key Laboratory of Intelligent Equipment for South China Sea Marine Ranching, Zhanjiang, 524088, China; Shenzhen Institute of Guangdong Ocean University, Shenzhen, 518108, China.
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Cetinkaya YN, Bulut O, Oktem HA, Yilmaz MD. Fluorescent silica nanoparticles as nano-chemosensors for the sequential detection of Pb 2+ ions and bacterial-spore biomarker dipicolinic acid (DPA) in aqueous solution. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2023; 303:123222. [PMID: 37542871 DOI: 10.1016/j.saa.2023.123222] [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: 04/28/2023] [Revised: 07/07/2023] [Accepted: 07/30/2023] [Indexed: 08/07/2023]
Abstract
Herein, we report fluorescein-labelled silica nanoparticles (FSNP) which serve as fluorescent nano-chemosensors for sequential detection of Pb2+ (which is a toxic heavy metal) and dipicolinic acid (DPA) (which is a distinctive indicator biomarker of bacterial spores) with high sensitivity and selectivity. The fluorescence of FSNP is quenched because of the complex formation between Pb2+ ions and surface amide groups, however, the fluorescence is recovered in contact with DPA, resulting from the association of DPA with surface bound Pb2+ ions. FSNP-Pb2+ complexes show high sensitivity towards DPA with a low detection limit of 850 nM which is approximately seventy times lower than the infectious dosage of bacterial spores (60 μM). Lateral flow test platform was further developed to show the applicability and practicability of our system.
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Affiliation(s)
- Yagmur Nur Cetinkaya
- Department of Materials Science and Nanotechnology, Graduate School of Natural and Applied Sciences, Konya Food and Agriculture University, 42080 Konya, Turkey
| | - Onur Bulut
- Department of Bioengineering, Faculty of Engineering and Architecture, Konya Food and Agriculture University, 42080 Konya, Turkey
| | - Huseyin Avni Oktem
- Department of Biological Sciences, Middle East Technical University, 06800 Ankara, Turkey; Nanobiz Technology Inc., Gallium Block No: 27 / 218, METU Technopolis, Ankara, Turkey
| | - M Deniz Yilmaz
- Department of Basic Sciences, Faculty of Engineering, Necmettin Erbakan University, 42140 Konya, Turkey; BITAM-Science and Technology Research and Application Center, Necmettin Erbakan University, 42140 Konya, Turkey.
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Koo TM, Ko MJ, Park BC, Kim MS, Kim YK. Fluorescent detection of dipicolinic acid as a biomarker in bacterial spores employing terbium ion-coordinated magnetite nanoparticles. JOURNAL OF HAZARDOUS MATERIALS 2021; 408:124870. [PMID: 33387720 DOI: 10.1016/j.jhazmat.2020.124870] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 12/04/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
Anthrax is a bioterror agent because of its toxicity and the tolerance of its bacterial spores. Thus, researchers have attempted to develop various nanomaterials to detect dipicolinic acid (DPA), a biomarker of bacterial spores. Nanomaterials containing lanthanide ions have received considerable attention, owing to their potential to exhibit high sensitivity and selectivity in the detection of DPA via chelation with molecules. However, the fluorescent signals of the lanthanide complex are quenchable because the nanomaterials simultaneously absorb the excitation and emission light. For the precise detection of DPA, pure signals have to be obtained from the complex by alleviating the quenching effect of the nanomaterials. In this study, we develop a structure with terbium ion (Tb3+)-coordinated magnetite (Fe3O4) nanoparticle to detect DPA. Tb3+ can be detached from the magnetite during chelation with the DPA, and the complex can emit the unencumbered signals with improved detection limit through the application of a magnetic field. The detection system exhibits a significantly lower detection limit (5.4 nM) than the infectious dosage of anthrax (60 μM) with high selectivity and chemical stability. This study informs the improvement of detection limits via the separation of nanomaterials and lanthanide complex.
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Affiliation(s)
- Thomas Myeongseok Koo
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Min Jun Ko
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Bum Chul Park
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea; Brain Korea Center for Smart Materials and Devices, Korea University, Seoul 02841, Republic of Korea
| | - Myeong Soo Kim
- Institute for High Technology Materials and Devices, Korea University, Seoul 02841, Republic of Korea
| | - Young Keun Kim
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea; Brain Korea Center for Smart Materials and Devices, Korea University, Seoul 02841, Republic of Korea; Institute for High Technology Materials and Devices, Korea University, Seoul 02841, Republic of Korea.
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Donmez M, Yilmaz MD, Kilbas B. Fluorescent detection of dipicolinic acid as a biomarker of bacterial spores using lanthanide-chelated gold nanoparticles. JOURNAL OF HAZARDOUS MATERIALS 2017; 324:593-598. [PMID: 27852519 DOI: 10.1016/j.jhazmat.2016.11.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 10/05/2016] [Accepted: 11/09/2016] [Indexed: 06/06/2023]
Abstract
Gold nanoparticles (GNPs) functionalized with ethylenediamine-lanthanide complexes (Eu-GNPs and Tb-GNPs) were used for the selective fluorescent detection of dipicolinic acid (DPA), a unique biomarker of bacterial spores, in water. Particles were characterized by transmission electron microscopy and zeta potential measurements. The coordination of DPA to the lanthanides resulted in the enhancement of the fluorescence. A selective response to DPA was observed over the nonselective binding of aromatic ligands. The ligand displacement strategy were also employed for the ratiometric fluorescent detection of DPA. 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedion (TFNB) was chosen as an antenna to synthesize ternary complexes. The addition of DPA on EuGNP:TFNB ternary complex quenched the initial emission of the complex at 615nm and increased the TFNB emission at 450nm when excited at 350nm. The results demonstrated that the ratiometric fluorescent detection of DPA was achieved by ligand displacement strategy.
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Affiliation(s)
- Mert Donmez
- Department of Chemistry, Faculty of Art and Sciences, Duzce University, Duzce 81620, Turkey
| | - M Deniz Yilmaz
- Department of Bioengineering, Faculty of Engineering and Architecture, Konya Food and Agriculture University, Konya 42080, Turkey.
| | - Benan Kilbas
- Department of Chemistry, Faculty of Art and Sciences, Duzce University, Duzce 81620, Turkey.
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Nanomechanical Characterization of Bacillus anthracis Spores by Atomic Force Microscopy. Appl Environ Microbiol 2016; 82:2988-2999. [PMID: 26969703 DOI: 10.1128/aem.00431-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 03/04/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The study of structures and properties of bacterial spores is important to understanding spore formation and biological responses to environmental stresses. While significant progress has been made over the years in elucidating the multilayer architecture of spores, the mechanical properties of the spore interior are not known. Here, we present a thermal atomic force microscopy (AFM) study of the nanomechanical properties of internal structures of Bacillus anthracis spores. We developed a nanosurgical sectioning method in which a stiff diamond AFM tip was used to cut an individual spore, exposing its internal structure, and a soft AFM tip was used to image and characterize the spore interior on the nanometer scale. We observed that the elastic modulus and adhesion force, including their thermal responses at elevated temperatures, varied significantly in different regions of the spore section. Our AFM images indicated that the peptidoglycan (PG) cortex of Bacillus anthracis spores consisted of rod-like nanometer-sized structures that are oriented in the direction perpendicular to the spore surface. Our findings may shed light on the spore architecture and properties. IMPORTANCE A nanosurgical AFM method was developed that can be used to probe the structure and properties of the spore interior. The previously unknown ultrastructure of the PG cortex of Bacillus anthracis spores was observed to consist of nanometer-sized rod-like structures that are oriented in the direction perpendicular to the spore surface. The variations in the nanomechanical properties of the spore section were largely correlated with its chemical composition. Different components of the spore materials showed different thermal responses at elevated temperatures.
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Abstract
Differential scanning calorimetry (DSC) measurements of dormant bacterial spores is traditionally associated with an endothermic transition at around 50 degrees C. This endothermic transition was described as an indicator for two main physico-chemical states in spores. These were a glassy state in the dormant spore core as a model for spore dormancy and a heat-activated state that generally facilitates spore resuscitation. The idea of a glassy state in dormant spores is based on the observation that a similar transition as in dormant spores was observed in low moisture biopolymers that are in a glassy state. Thermal properties of spores of Bacillus subtilis and B. cereus in a dormant and germinated, resuscitated state and of an outer and an inner coatless spore mutant of B. subtilis were investigated. Biopolymers with low moisture (<15%) and high moisture (>30%) contents such as maize starch, pectin, RNA and DNA were further studied. Critical evaluation of results revealed that the low temperature transition in dormant spores has some similarities to those observed in glassy biopolymers, but also to those of fully hydrated proteins and therefore does not necessarily indicate a glassy low moisture state. Its origin can also be attributed to the outer spore coats and it occurred at a lower temperature and for a shorter duration to be of significance for thermal heat activation of spores.
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Farkas J, Andrássy E, Formanek Z, Mészáros L. Luminometric and differential scanning calorimetry (DSC) studies on heat- and radiation inactivation of Bacillus subtilis luxAB spores. Acta Microbiol Immunol Hung 2002; 49:141-50. [PMID: 12073820 DOI: 10.1556/amicr.49.2002.1.14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A bioluminescent derivative of Bacillus subtilis containing a plasmid encoding a luxAB fusion under control of a vegetative promoter and gives bioluminescence upon addition of an exogenous long-chain aldehyde has been used as test organism. Its spore populations have been produced and their heat- and radiation survival curves established. Heat-sensitization effect of pre-irradiation of spores was proven not only by colony counting but also with differential scanning calorimetry. Under a linearly programmed temperature increase, the heat destruction of spores surviving 2.5 kGy gamma irradiation resulted in at a few centigrade lower temperature than that of untreated spores. Heat denaturation endotherms in the DSC-thermogram of irradiated spores were shifted to lower temperatures as well. Comparative turbidimetric, luminometric and phase-contrast microscopic studies of untreated, heat-treated and irradiated spore populations showed that the kinetics of germination and the light emission during germination of radiation-inactivated spores were the same as those of untreated spores, revealing that the pre-formed luciferase enzyme packaged into the spores during sporulation remained intact after an irradiation dose causing 90% decrease in number of colony forming spores. Therefore, in contrast to heat-treated spores, the initial bioluminescence reading upon germination of irradiated spores does not reflect the viable count of their population.
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Affiliation(s)
- J Farkas
- Department of Refrigeration and Livestock Products' Technology, Szent István University, Ménesi út 45, H-1118 Budapest, Hungary
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Leuschner RG, Lillford PJ. Investigation of bacterial spore structure by high resolution solid-state nuclear magnetic resonance spectroscopy and transmission electron microscopy. Int J Food Microbiol 2001; 63:35-50. [PMID: 11205952 DOI: 10.1016/s0168-1605(00)00396-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
High resolution solid-state nuclear magnetic resonance spectroscopy (NMR) in combination with transmission electron microscopy (TEM) of spores of Bacillus cereus, an outer coatless mutant B. subtilis 322, an inner coatless mutant B. subtilis 325 and of germinated spores of B. subtilis CMCC 604 were carried out. Structural differences in the coats, mainly protein of spores were reflected by NMR spectra which indicated also differences in molecular mobility of carbohydrates which was partially attributed to the cortex. Dipicolinic acid (DPA) of spores of B. cereus displayed a high degree of solid state order and may be crystalline. Heat activation was studied on spores of B. subtilis 357 lux + and revealed a structural change when analysed by TEM but this was not associated with increases in molecular mobility since no effects were measured by NMR.
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Affiliation(s)
- R G Leuschner
- Unilever Research Colworth, Sharnbrook, Bedford, UK.
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Leuschner RGK, Lillford PJ. Effects of hydration on molecular mobility in phase-bright Bacillus subtilis spores. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 1):49-55. [PMID: 10658651 DOI: 10.1099/00221287-146-1-49] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The molecular mobility of 31P and 13C in dormant Bacillus subtilis spore samples with different water concentrations was investigated by high-resolution solid-state NMR. Lowest molecular mobility was observed in freeze-dried preparations. Rehydration to a 10% weight increase resulted in increases in molecular motions and addition of excess water furthered this effect. A spore slurry which had been freeze-dried displayed after addition of excess water similar NMR spectra to native wet preparations. Dipicolinic acid (DPA), which is mainly located in the core, was detected at all hydration levels in 13C cross-polarization magic angle spinning (CPMAS) but not in single-pulse magic angle spinning (SPMAS) spectra, indicating that hydration had no effect on its mobility. The molecular mobility of 31P, present mainly in core-specific components, was strongly dependent on hydration. This result suggests reversible water migration between inner spore compartments and the environment, whereas 13C spectra of DPA indicate that it is immobilized in a water-insoluble network in the core. Scanning transmission electron microscopy revealed that freeze-dried spores were significantly longer and narrower than fully hydrated spores and had a 3% smaller volume.
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