TY  - CONF
AU  - Gligorijević, Nikola
AU  - Stanić-Vučinić, Dragana
AU  - Mutić, Tamara
AU  - Lujić, Tamara
AU  - Ćirković Veličković, Tanja
PY  - 2023
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/6524
AB  - Microplastic represents one of the major types of pollutants in modern era. Over several years of research in the field of microplastic, there are still many unknown gaps, including the effects and mechanisms of action of these particles on human health. Studies in this field conducted experiments on cells and human tissues or animals like rats and mice. While these studies suggest the toxic effects of microplastic, it is not clear if concentrations used for exposure are relevant for humans. Also, most of the studies used spherical polystyrene, which does not reflect well the diversity of microplastic particles found in nature. Another gap is lack of studies describing direct interactions of microplastics and proteins. While it is generally known that proteins form corona around microplastic particles, affinity studies and consequences on protein structure are usually missing. The aim of this work was to analyze interaction of a major egg white protein and allergen, ovalbumin to several to microplastic particles, including polystyrene (PS) of 120 and 500 μm in size and polyethylene terephthalate (PET) of 120 μm in size. Binding affinity was determined at both acidic, pH 3 and neutral, pH 7 conditions, at the room temperature, by measuring bulk ovalbumin concentration in supernatants at the equilibrium time. Several binding models, including Langmuir,
Freundlich, Redlich–Peterson and Guggenheim-Anderson-de Boer (GAB), were used to determine binding parameters. The formation of soft and hard corona was analyzed according to the published protocol [1]. Structural analysis was performed using near and far-UV CD spectrometry.
Obtained results showed that ovalbumin binds to both PS and PET. All binding models indicated that ovalbumin binds with higher affinity to tested microplastics on pH 3, compared to pH 7, with the highest affinity being calculated for PS 120 μm. Further analysis showed that ovalbumin forms both soft and hard corona onto the surface of all three microplastics. Structural alterations of ovalbumin as a consequence of its interaction with microplastic was shown to be both pH and
microplastic type dependent. Also, more pronounced effect on its tertiary structure was observed, compared to secondary. At pH3, tertiary structure of bulk ovalbumin becomes destabilized, especially in the presence of PET 120 μm and PS 500 μm, while at pH 7, structural stabilization is observed, especially in the presence of PS 120 μm. Considering that the microplastic was discovered in eggs [2], obtained results suggest that direct interactions of native ovalbumin with microplastic particles could have influence on its structure and thus affect its techno-functional properties.
PB  - Belgrade : Serbian Chemical Society
C3  - Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023
T1  - Binding and corona formation of ovalbumin to polystyrene and polyethylene terephthalate microplastics under neutral and acidic conditions
SP  - 137
EP  - 137
UR  - https://hdl.handle.net/21.15107/rcub_cer_6524
ER  - 

@conference{
author = "Gligorijević, Nikola and Stanić-Vučinić, Dragana and Mutić, Tamara and Lujić, Tamara and Ćirković Veličković, Tanja",
year = "2023",
abstract = "Microplastic represents one of the major types of pollutants in modern era. Over several years of research in the field of microplastic, there are still many unknown gaps, including the effects and mechanisms of action of these particles on human health. Studies in this field conducted experiments on cells and human tissues or animals like rats and mice. While these studies suggest the toxic effects of microplastic, it is not clear if concentrations used for exposure are relevant for humans. Also, most of the studies used spherical polystyrene, which does not reflect well the diversity of microplastic particles found in nature. Another gap is lack of studies describing direct interactions of microplastics and proteins. While it is generally known that proteins form corona around microplastic particles, affinity studies and consequences on protein structure are usually missing. The aim of this work was to analyze interaction of a major egg white protein and allergen, ovalbumin to several to microplastic particles, including polystyrene (PS) of 120 and 500 μm in size and polyethylene terephthalate (PET) of 120 μm in size. Binding affinity was determined at both acidic, pH 3 and neutral, pH 7 conditions, at the room temperature, by measuring bulk ovalbumin concentration in supernatants at the equilibrium time. Several binding models, including Langmuir,
Freundlich, Redlich–Peterson and Guggenheim-Anderson-de Boer (GAB), were used to determine binding parameters. The formation of soft and hard corona was analyzed according to the published protocol [1]. Structural analysis was performed using near and far-UV CD spectrometry.
Obtained results showed that ovalbumin binds to both PS and PET. All binding models indicated that ovalbumin binds with higher affinity to tested microplastics on pH 3, compared to pH 7, with the highest affinity being calculated for PS 120 μm. Further analysis showed that ovalbumin forms both soft and hard corona onto the surface of all three microplastics. Structural alterations of ovalbumin as a consequence of its interaction with microplastic was shown to be both pH and
microplastic type dependent. Also, more pronounced effect on its tertiary structure was observed, compared to secondary. At pH3, tertiary structure of bulk ovalbumin becomes destabilized, especially in the presence of PET 120 μm and PS 500 μm, while at pH 7, structural stabilization is observed, especially in the presence of PS 120 μm. Considering that the microplastic was discovered in eggs [2], obtained results suggest that direct interactions of native ovalbumin with microplastic particles could have influence on its structure and thus affect its techno-functional properties.",
publisher = "Belgrade : Serbian Chemical Society",
journal = "Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023",
title = "Binding and corona formation of ovalbumin to polystyrene and polyethylene terephthalate microplastics under neutral and acidic conditions",
pages = "137-137",
url = "https://hdl.handle.net/21.15107/rcub_cer_6524"
}

Gligorijević, N., Stanić-Vučinić, D., Mutić, T., Lujić, T.,& Ćirković Veličković, T.. (2023). Binding and corona formation of ovalbumin to polystyrene and polyethylene terephthalate microplastics under neutral and acidic conditions. in Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023
Belgrade : Serbian Chemical Society., 137-137.
https://hdl.handle.net/21.15107/rcub_cer_6524

Gligorijević N, Stanić-Vučinić D, Mutić T, Lujić T, Ćirković Veličković T. Binding and corona formation of ovalbumin to polystyrene and polyethylene terephthalate microplastics under neutral and acidic conditions. in Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023. 2023;:137-137.
https://hdl.handle.net/21.15107/rcub_cer_6524 .

Gligorijević, Nikola, Stanić-Vučinić, Dragana, Mutić, Tamara, Lujić, Tamara, Ćirković Veličković, Tanja, "Binding and corona formation of ovalbumin to polystyrene and polyethylene terephthalate microplastics under neutral and acidic conditions" in Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023 (2023):137-137,
https://hdl.handle.net/21.15107/rcub_cer_6524 .

TY  - CONF
AU  - Lujić, Tamara
AU  - Gligorijević, Nikola
AU  - Stanić-Vučinić, Dragana
AU  - Ćirković Veličković, Tanja
PY  - 2023
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/6525
AB  - Ovalbumin (OVA) is the most abundant protein in chicken egg white. It is one of the major allergens in eggs. Micro- and nanoplatic particles (MNPs) are a widespread contaminant and have been found in food and water. It is still unclear how MNPs might affect human health. However, due to their large surface area they have been found to bind various biopolymers,
including proteins. These biopolymers can be bound more strongly or loosely, and are referred to as hard and soft corona, respectfully [1]. MPs have been found in eggs, in the size range of 50-100 μm [2]. It is shown that these particles can interact with proteins and induce structural changes, but there is still not enough information on this topic [3]. These structural changes could lead to a decreased digestibility in the gastrointestinal tract, which could increase the immune
response to known allergens. The aim of this study was to determine whether there are structural changes present in the OVA after incubation with two types of MPs – 120 μm polyethylene terephthalate (PET) and 120 μm polystyrene (PS) and whether they could influence
digestion of OVA with gastrointestinal enzymes. 20 mg of MPs were incubated with 1.3 mg/mL ovalbumin for 4 h at room temperature in a 20 mM phosphate buffer at pH 7. Bulk ovalbumin was separated from the MPs by centrifugation and by filtration through a 0.22 μm PVDF filter. Soft corona was obtained by washing the MPs with water, and the MPs were later removed as described with bulk ovalbumin. Formation of amyloids was monitored with a Thioflavin T (ThT) assay at room temperature and after thermal treatment, and additional structural analysis was performed by circular dichroism (CD) spectrometry in the far-UV region. Thermal stability was also determined by spectrofluorimetry. Digestion with two proteases (pepsin and trypsin) was performed to determine whether there is a change in the gastrointestinal digestibility of OVA.
Results from the ThT assay show that at room temperature there is no significant difference between the fluorescence emission obtained for all samples, with bulk OVA from both MPs showing a slight decrease. However, there is an increase of fluorescence after thermal treatment in all OVA samples, where OVA from the soft corona emits significantly less fluorescence
than control and bulk samples for both types of MPs. Additionally, soft coronas have been shown to have more β-sheet content than other samples, which is more pronounced for OVA incubated with PET. For the heated samples there is a sharp change from α-helix to β-sheets in all the samples, but it is the most dramatic in the soft coronas. This could impose rigidity to the tertiary structure, which would explain why the ThT molecule does not bind as strongly. Despite differences in both the secondary and tertiary structure, the thermal stability is almost the same in all samples. Digestion of the samples shows that the soft corona incubated with PS tends to be more resistant to trypsin than other samples after 2 min, but it is not significant. For digestion with pepsin there is no difference between the samples. In conjunction with the previous results, which indicates a structural stabilisation of the soft corona at pH 7, it is not surprising that there is an increased resistance to trypsin, compared to pepsin which is a gastric enzyme and for which digestion is performed at an acidic pH. In conclusion, there is a structural change present in samples upon contact with MPs, particularly in the soft corona, of which the most pronounced is a decrease of α-helix content and increase in β-sheet content as determined by far-UV CD.
This leads to a structural stabilization which could further impact the digestibility of the OVA protein and impact its allergenicity. However, this must be confirmed with further experiments.
PB  - Belgrade : Serbian Chemical Society
C3  - Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023
T1  - Investigation of structural changes in ovalbumin induced by two types of MPs and its impact on protein digestibility
SP  - 153
EP  - 153
UR  - https://hdl.handle.net/21.15107/rcub_cer_6525
ER  - 

@conference{
author = "Lujić, Tamara and Gligorijević, Nikola and Stanić-Vučinić, Dragana and Ćirković Veličković, Tanja",
year = "2023",
abstract = "Ovalbumin (OVA) is the most abundant protein in chicken egg white. It is one of the major allergens in eggs. Micro- and nanoplatic particles (MNPs) are a widespread contaminant and have been found in food and water. It is still unclear how MNPs might affect human health. However, due to their large surface area they have been found to bind various biopolymers,
including proteins. These biopolymers can be bound more strongly or loosely, and are referred to as hard and soft corona, respectfully [1]. MPs have been found in eggs, in the size range of 50-100 μm [2]. It is shown that these particles can interact with proteins and induce structural changes, but there is still not enough information on this topic [3]. These structural changes could lead to a decreased digestibility in the gastrointestinal tract, which could increase the immune
response to known allergens. The aim of this study was to determine whether there are structural changes present in the OVA after incubation with two types of MPs – 120 μm polyethylene terephthalate (PET) and 120 μm polystyrene (PS) and whether they could influence
digestion of OVA with gastrointestinal enzymes. 20 mg of MPs were incubated with 1.3 mg/mL ovalbumin for 4 h at room temperature in a 20 mM phosphate buffer at pH 7. Bulk ovalbumin was separated from the MPs by centrifugation and by filtration through a 0.22 μm PVDF filter. Soft corona was obtained by washing the MPs with water, and the MPs were later removed as described with bulk ovalbumin. Formation of amyloids was monitored with a Thioflavin T (ThT) assay at room temperature and after thermal treatment, and additional structural analysis was performed by circular dichroism (CD) spectrometry in the far-UV region. Thermal stability was also determined by spectrofluorimetry. Digestion with two proteases (pepsin and trypsin) was performed to determine whether there is a change in the gastrointestinal digestibility of OVA.
Results from the ThT assay show that at room temperature there is no significant difference between the fluorescence emission obtained for all samples, with bulk OVA from both MPs showing a slight decrease. However, there is an increase of fluorescence after thermal treatment in all OVA samples, where OVA from the soft corona emits significantly less fluorescence
than control and bulk samples for both types of MPs. Additionally, soft coronas have been shown to have more β-sheet content than other samples, which is more pronounced for OVA incubated with PET. For the heated samples there is a sharp change from α-helix to β-sheets in all the samples, but it is the most dramatic in the soft coronas. This could impose rigidity to the tertiary structure, which would explain why the ThT molecule does not bind as strongly. Despite differences in both the secondary and tertiary structure, the thermal stability is almost the same in all samples. Digestion of the samples shows that the soft corona incubated with PS tends to be more resistant to trypsin than other samples after 2 min, but it is not significant. For digestion with pepsin there is no difference between the samples. In conjunction with the previous results, which indicates a structural stabilisation of the soft corona at pH 7, it is not surprising that there is an increased resistance to trypsin, compared to pepsin which is a gastric enzyme and for which digestion is performed at an acidic pH. In conclusion, there is a structural change present in samples upon contact with MPs, particularly in the soft corona, of which the most pronounced is a decrease of α-helix content and increase in β-sheet content as determined by far-UV CD.
This leads to a structural stabilization which could further impact the digestibility of the OVA protein and impact its allergenicity. However, this must be confirmed with further experiments.",
publisher = "Belgrade : Serbian Chemical Society",
journal = "Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023",
title = "Investigation of structural changes in ovalbumin induced by two types of MPs and its impact on protein digestibility",
pages = "153-153",
url = "https://hdl.handle.net/21.15107/rcub_cer_6525"
}

Lujić, T., Gligorijević, N., Stanić-Vučinić, D.,& Ćirković Veličković, T.. (2023). Investigation of structural changes in ovalbumin induced by two types of MPs and its impact on protein digestibility. in Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023
Belgrade : Serbian Chemical Society., 153-153.
https://hdl.handle.net/21.15107/rcub_cer_6525

Lujić T, Gligorijević N, Stanić-Vučinić D, Ćirković Veličković T. Investigation of structural changes in ovalbumin induced by two types of MPs and its impact on protein digestibility. in Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023. 2023;:153-153.
https://hdl.handle.net/21.15107/rcub_cer_6525 .

Lujić, Tamara, Gligorijević, Nikola, Stanić-Vučinić, Dragana, Ćirković Veličković, Tanja, "Investigation of structural changes in ovalbumin induced by two types of MPs and its impact on protein digestibility" in Book of Abstracts of the XXII EuroFoodChem Congress, Belgrade, Serbia, 14-16 June 2023 (2023):153-153,
https://hdl.handle.net/21.15107/rcub_cer_6525 .

TY  - CONF
AU  - Radomirović, Mirjana
AU  - Gligorijević, Nikola
AU  - Rajković, Andreja
AU  - Ćirković Veličković, Tanja
PY  - 2022
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/6799
AB  - Tropomyosin (TPM) is considered a major allergen among different shellfish species.
Developing sensitive, specific, and reliable methods for quantifying TPM in food products
is crucial for persons allergic to shellfish. We have previously developed a highly sensitive
sandwich ELISA method for quantifying shrimp TPM. Despite high amino acid sequence
homology between shrimp and mussels TPM, the method has not been reliable for
quantifying TPM from mussels, underestimating its concentration up to three orders of
magnitude. Therefore, this work aimed to develop alternative immunological methods for
mussel TPM quantification. Western blot, dot blot, and indirect ELISA using monoclonal
anti-TPM antibody and alkaline phosphatase-labeled secondary antibody were developed
and compared in terms of their sensitivity. Tropomyosin in mussels extracts was quantified
using highly purified natural shrimp tropomyosin as standard. The linear range for TPM
quantification using dot blot was between 5 and 50 μg/mL, while Western blot has slightly
increased sensitivity, with a linear range between 1.25 and 12.5 μg/mL. Indirect ELISA
has further improved the sensitivity of TPM quantification, with a 0.04-0.4 μg/mL linear
range. Additional work will be performed to enhance the sensitivity of the presented
methods, with the final aim of reducing risks of inadvertent food contamination.
PB  - Serbian Biochemical Society
PB  - University of Belgrade - Faculty of Chemistry
C3  - Proceedings - XI Conference of Serbian Biochemical Society "Amazing Biochemistry", 22.09.2022. Novi Sad, Serbia, 2022, 2022, 141- Publisher:
T1  - Development and comparison of Western blot, dot blot and ELISA for mussel tropomyosin quantification
SP  - 125
EP  - 125
UR  - https://hdl.handle.net/21.15107/rcub_cer_6799
ER  - 

@conference{
author = "Radomirović, Mirjana and Gligorijević, Nikola and Rajković, Andreja and Ćirković Veličković, Tanja",
year = "2022",
abstract = "Tropomyosin (TPM) is considered a major allergen among different shellfish species.
Developing sensitive, specific, and reliable methods for quantifying TPM in food products
is crucial for persons allergic to shellfish. We have previously developed a highly sensitive
sandwich ELISA method for quantifying shrimp TPM. Despite high amino acid sequence
homology between shrimp and mussels TPM, the method has not been reliable for
quantifying TPM from mussels, underestimating its concentration up to three orders of
magnitude. Therefore, this work aimed to develop alternative immunological methods for
mussel TPM quantification. Western blot, dot blot, and indirect ELISA using monoclonal
anti-TPM antibody and alkaline phosphatase-labeled secondary antibody were developed
and compared in terms of their sensitivity. Tropomyosin in mussels extracts was quantified
using highly purified natural shrimp tropomyosin as standard. The linear range for TPM
quantification using dot blot was between 5 and 50 μg/mL, while Western blot has slightly
increased sensitivity, with a linear range between 1.25 and 12.5 μg/mL. Indirect ELISA
has further improved the sensitivity of TPM quantification, with a 0.04-0.4 μg/mL linear
range. Additional work will be performed to enhance the sensitivity of the presented
methods, with the final aim of reducing risks of inadvertent food contamination.",
publisher = "Serbian Biochemical Society, University of Belgrade - Faculty of Chemistry",
journal = "Proceedings - XI Conference of Serbian Biochemical Society "Amazing Biochemistry", 22.09.2022. Novi Sad, Serbia, 2022, 2022, 141- Publisher:",
title = "Development and comparison of Western blot, dot blot and ELISA for mussel tropomyosin quantification",
pages = "125-125",
url = "https://hdl.handle.net/21.15107/rcub_cer_6799"
}

Radomirović, M., Gligorijević, N., Rajković, A.,& Ćirković Veličković, T.. (2022). Development and comparison of Western blot, dot blot and ELISA for mussel tropomyosin quantification. in Proceedings - XI Conference of Serbian Biochemical Society "Amazing Biochemistry", 22.09.2022. Novi Sad, Serbia, 2022, 2022, 141- Publisher:
Serbian Biochemical Society., 125-125.
https://hdl.handle.net/21.15107/rcub_cer_6799

Radomirović M, Gligorijević N, Rajković A, Ćirković Veličković T. Development and comparison of Western blot, dot blot and ELISA for mussel tropomyosin quantification. in Proceedings - XI Conference of Serbian Biochemical Society "Amazing Biochemistry", 22.09.2022. Novi Sad, Serbia, 2022, 2022, 141- Publisher:. 2022;:125-125.
https://hdl.handle.net/21.15107/rcub_cer_6799 .

Radomirović, Mirjana, Gligorijević, Nikola, Rajković, Andreja, Ćirković Veličković, Tanja, "Development and comparison of Western blot, dot blot and ELISA for mussel tropomyosin quantification" in Proceedings - XI Conference of Serbian Biochemical Society "Amazing Biochemistry", 22.09.2022. Novi Sad, Serbia, 2022, 2022, 141- Publisher: (2022):125-125,
https://hdl.handle.net/21.15107/rcub_cer_6799 .