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Rudnizky S, Murray PJ, Wolfe CH, Ha T. Single-Macromolecule Studies of Eukaryotic Genomic Maintenance. Annu Rev Phys Chem 2024; 75:209-230. [PMID: 38382570 DOI: 10.1146/annurev-physchem-090722-010601] [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] [Indexed: 02/23/2024]
Abstract
Genomes are self-organized and self-maintained as long, complex macromolecules of chromatin. The inherent heterogeneity, stochasticity, phase separation, and chromatin dynamics of genome operation make it challenging to study genomes using ensemble methods. Various single-molecule force-, fluorescent-, and sequencing-based techniques rooted in different disciplines have been developed to fill critical gaps in the capabilities of bulk measurements, each providing unique, otherwise inaccessible, insights into the structure and maintenance of the genome. Capable of capturing molecular-level details about the organization, conformational changes, and packaging of genetic material, as well as processive and stochastic movements of maintenance factors, a single-molecule toolbox provides an excellent opportunity for collaborative research to understand how genetic material functions in health and malfunctions in disease. In this review, we discuss novel insights brought to genomic sciences by single-molecule techniques and their potential to continue to revolutionize the field-one molecule at a time.
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Affiliation(s)
- Sergei Rudnizky
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Peter J Murray
- Department of Biology, Johns Hopkins University, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
| | - Clara H Wolfe
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Taekjip Ha
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA;
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, USA
- Howard Hughes Medical Institute, Boston Children's Hospital, Boston, Massachusetts, USA
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Kuroda K, Ishii Y, Takasu S, Kijima A, Matsushita K, Masumura KI, Nohmi T, Umemura T. Possible contribution of 8-hydroxydeoxyguanosine to gene mutations in the kidney DNA of gpt delta rats following potassium bromate treatment. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2024; 894:503729. [PMID: 38432777 DOI: 10.1016/j.mrgentox.2024.503729] [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: 12/05/2023] [Revised: 01/15/2024] [Accepted: 01/18/2024] [Indexed: 03/05/2024]
Abstract
8-Hydroxydeoxyguanosine (8-OHdG) is well known not only as an effective biomarker of oxidative stress but also as a mutagenic DNA modification. Incorporation of dAMP at the opposite site of 8-OHdG induces G>T or A>C transversions. However, in vivo analyses of gene mutations caused by potassium bromate (KBrO3), which can induce 8-OHdG at carcinogenic target sites, showed that G>T was prominent in the small intestines of mice, but not in the kidneys of rats. Because KBrO3 was a much clearer carcinogen in the kidneys of rats, detailed analyses of gene mutations in the kidney DNA of rats treated with KBrO3 could improve our understanding of oxidative stress-mediated carcinogenesis. In the current study, site-specific reporter gene mutation assays were performed in the kidneys of gpt delta rats treated with KBrO3. Groups of 5 gpt delta rats were treated with KBrO3 at concentrations of 0, 125, 250, or 500 ppm in the drinking water for 9 weeks. At necropsy, the kidneys were macroscopically divided into the cortex and medulla. 8-OHdG levels in DNA extracted from the cortex were dramatically elevated at concentrations of 250 ppm and higher compared with those from the medulla. Cortex-specific increases in mutant frequencies in gpt and red/gam genes were found at 500 ppm. Mutation spectrum and sequence analyses of their mutants demonstrated significant elevations in A>T transversions in the gpt gene and single base deletions at guanine or adenine in the gpt or red/gam genes. While A>T transversions and single base deletions of adenine may result from the oxidized modification of adenine, the contribution of 8-OHdG to gene mutations was limited despite possible participation of the 8-OHdG repair process in guanine deletion.
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Affiliation(s)
- Ken Kuroda
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Yuji Ishii
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Shinji Takasu
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Aki Kijima
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Kohei Matsushita
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Ken-Ichi Masumura
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Takehiko Nohmi
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan
| | - Takashi Umemura
- Division of Pathology, National Institute of Health Sciences, 3-25-26 Tonomachi, Kawasaki-ku, Kawasaki-shi, Kanagawa, 210-9501, Japan; Faculty of Animal Health Technology, Yamzaki University of Animal Health Technology, 4-7-2 Minamiosawa, Hachioji-shi, Tokyo, Japan.
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Bakman AS, Boichenko SS, Kuznetsova AA, Ishchenko AA, Saparbaev M, Kuznetsov NA. Coordination between human DNA polymerase β and apurinic/apyrimidinic endonuclease 1 in the course of DNA repair. Biochimie 2024; 216:126-136. [PMID: 37806619 DOI: 10.1016/j.biochi.2023.10.007] [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: 07/13/2023] [Revised: 09/08/2023] [Accepted: 10/06/2023] [Indexed: 10/10/2023]
Abstract
Coordination of enzymatic activities in the course of base excision repair (BER) is essential to ensure complete repair of damaged bases. Two major mechanisms underlying the coordination of BER are known today: the "passing the baton" model and a model of preassembled stable multiprotein repair complexes called "repairosomes." In this work, we aimed to elucidate the coordination between human apurinic/apyrimidinic (AP) endonuclease APE1 and DNA polymerase Polβ in BER through studying an impact of APE1 on Polβ-catalyzed nucleotide incorporation into different model substrates that mimic different single-strand break (SSB) intermediates arising along the BER pathway. It was found that APE1's impact on separate stages of Polβ's catalysis depends on the nature of a DNA substrate. In this complex, APE1 removed 3' blocking groups and corrected Polβ-catalyzed DNA synthesis in a coordinated manner. Our findings support the hypothesis that Polβ not only can displace APE1 from damaged DNA within the "passing the baton" model but also performs the gap-filling reaction in the ternary complex with APE1 according to the "repairosome" model. Taken together, our results provide new insights into coordination between APE1 and Polβ during the BER process.
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Affiliation(s)
- Artemiy S Bakman
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad, Lavrentyeva, Novosibirsk, 630090, Russia
| | - Stanislav S Boichenko
- Department of Natural Sciences, Novosibirsk State University, 2 Pirogova Str., Novosibirsk, 630090, Russia
| | - Aleksandra A Kuznetsova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad, Lavrentyeva, Novosibirsk, 630090, Russia
| | - Alexander A Ishchenko
- Group «Mechanisms of DNA Repair and Carcinogenesis», Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805, Villejuif, France
| | - Murat Saparbaev
- Group «Mechanisms of DNA Repair and Carcinogenesis», Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805, Villejuif, France
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad, Lavrentyeva, Novosibirsk, 630090, Russia; Department of Natural Sciences, Novosibirsk State University, 2 Pirogova Str., Novosibirsk, 630090, Russia.
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Fairlamb MS, Spies M, Washington MT, Freudenthal BD. Visualizing the coordination of apurinic/apyrimidinic endonuclease (APE1) and DNA polymerase β during base excision repair. J Biol Chem 2023; 299:104636. [PMID: 36963489 PMCID: PMC10148159 DOI: 10.1016/j.jbc.2023.104636] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/05/2023] [Accepted: 03/10/2023] [Indexed: 03/26/2023] Open
Abstract
Base excision repair (BER) is carried out by a series of proteins that function in a step-by-step process to identify, remove, and replace DNA damage. During BER, the DNA transitions through various intermediate states as it is processed by each DNA repair enzyme. Left unrepaired, these BER intermediates can transition into double-stranded DNA breaks and promote genome instability. Previous studies have proposed a short-lived complex consisting of the BER intermediate, the incoming enzyme, and the outgoing enzyme at each step of the BER pathway to protect the BER intermediate. The transfer of BER intermediates between enzymes, known as BER coordination or substrate channeling, remains poorly understood. Here, we utilize single-molecule total internal reflection fluorescence microscopy to investigate the mechanism of BER coordination between apurinic/apyrimidinic endonuclease 1 (APE1) and DNA polymerase β (Pol β). When preformed complexes of APE1 and the incised abasic site product (APE1 product and Pol β substrate) were subsequently bound by Pol β, the Pol β enzyme dissociated shortly after binding in most of the observations. In the events where Pol β binding was followed by APE1 dissociation during substrate channeling, Pol β remained bound for a longer period of time to allow disassociation of APE1. Our results indicate that transfer of the BER intermediate from APE1 to Pol β during BER is dependent on the dissociation kinetics of APE1 and the duration of the ternary complex on the incised abasic site.
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Affiliation(s)
- Max S Fairlamb
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Maria Spies
- Department of Biochemistry and Molecular Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - M Todd Washington
- Department of Biochemistry and Molecular Biology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Bret D Freudenthal
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas, USA; Department of Cancer Biology, University of Kansas Medical Center, Kansas City, Kansas, USA; University of Kansas Cancer Center, Kansas City, Kansas, USA.
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Bakman AS, Kuznetsova AA, Yanshole LV, Ishchenko AA, Saparbaev M, Fedorova OS, Kuznetsov NA. Fluorescently labeled human apurinic/apyrimidinic endonuclease APE1 reveals effects of DNA polymerase β on the APE1-DNA interaction. DNA Repair (Amst) 2023; 123:103450. [PMID: 36689867 DOI: 10.1016/j.dnarep.2023.103450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 12/26/2022] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
The base excision repair (BER) pathway involves sequential action of DNA glycosylases and apurinic/apyrimidinic (AP) endonucleases to incise damaged DNA and prepare DNA termini for incorporation of a correct nucleotide by DNA polymerases. It has been suggested that the enzymatic steps in BER include recognition of a product-enzyme complex by the next enzyme in the pathway, resulting in the "passing-the-baton" model of transfer of DNA intermediates between enzymes. To verify this model, in this work, we aimed to create a suitable experimental system. We prepared APE1 site-specifically labeled with a fluorescent reporter that is sensitive to stages of APE1-DNA binding, of formation of the catalytic complex, and of subsequent dissociation of the enzyme-product complex. Interactions of the labeled APE1 with various model DNA substrates (containing an abasic site) of varied lengths revealed that the enzyme remains mostly in complex with the DNA product. By means of the fluorescently labeled APE1 in combination with a stopped-flow fluorescence assay, it was found that Polβ stimulates both i) APE1 binding to an abasic-site-containing DNA duplex with the formation of a catalytically competent complex and ii) the dissociation of APE1 from its product. These findings confirm DNA-mediated coordination of APE1 and Polβ activities and suggest that Polβ is the key trigger of the DNA transfer between the enzymes participating in initial steps of BER.
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Affiliation(s)
- Artemiy S Bakman
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Aleksandra A Kuznetsova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Lyudmila V Yanshole
- International Tomography Center SB RAS, 3a Institutskaya Str., Novosibirsk 630090, Russia
| | - Alexander A Ishchenko
- Group "Mechanisms of DNA Repair and Carcinogenesis", Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805 Villejuif, France
| | - Murat Saparbaev
- Group "Mechanisms of DNA Repair and Carcinogenesis", Gustave Roussy Cancer Campus, CNRS UMR9019, Université Paris-Saclay, 94805 Villejuif, France; NCJSC "Al-Farabi Kazakh National University" Almaty, Kazakhstan
| | - Olga S Fedorova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of Russian Academy of Sciences (SB RAS), 8 Prospekt Akad. Lavrentyeva, Novosibirsk 630090, Russia; Department of Natural Sciences, Novosibirsk State University, 2 Pirogova Str., Novosibirsk 630090, Russia.
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Mechanistic Investigation of the Androgen Receptor DNA-Binding Domain and Modulation via Direct Interactions with DNA Abasic Sites: Understanding the Mechanisms Involved in Castration-Resistant Prostate Cancer. Int J Mol Sci 2023; 24:ijms24021270. [PMID: 36674785 PMCID: PMC9864221 DOI: 10.3390/ijms24021270] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/28/2022] [Accepted: 12/30/2022] [Indexed: 01/11/2023] Open
Abstract
The androgen receptor (AR) is an important drug target in prostate cancer and a driver of castration-resistant prostate cancer (CRPC). A significant challenge in designing effective drugs lies in targeting constitutively active AR variants and, most importantly, nearly all AR variants lacking the ligand-binding domain (LBD). Recent findings show that an AR's constitutive activity may occur in the presence of somatic DNA mutations within non-coding regions, but the role of these mutations remains elusive. The discovery of new drugs targeting CRPC is hampered by the limited molecular understanding of how AR binds mutated DNA sequences, frequently observed in prostate cancer, and how mutations within the protein and DNA regulate AR-DNA interactions. Using atomistic molecular dynamics (MD) simulations and quantum mechanical calculations, we focused our efforts on (i) rationalising the role of several activating DBD mutations linked to prostate cancer, and (ii) DBD interactions in the presence of abasic DNA lesions, which frequently occur in CRPC. Our results elucidate the role of mutations within DBD through their modulation of the intrinsic dynamics of the DBD-DNA ternary complex. Furthermore, our results indicate that the DNA apurinic lesions occurring in the androgen-responsive element (ARE) enhance direct AR-DNA interactions and stabilise the DBD homodimerisation interface. Moreover, our results strongly suggest that those abasic lesions may form reversible covalent crosslinks between DNA and lysine residues of an AR via a Schiff base. In addition to providing an atomistic model explaining how protein mutations within the AR DNA-binding domain affect AR dimerisation and AR-DNA interactions, our findings provide insight into how somatic mutations occurring in DNA non-coding regions may activate ARs. These mutations are frequently observed in prostate cancer and may contribute to disease progression by enhancing direct AR-DNA interactions.
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Yu Y, Li A, Li S, Zheng B, Ma J, Liu Y, Kou X, Xue Z. Mechanism of biochanin A alleviating PM 2.5-induced oxidative damage based on an XRCC1 knockout BEAS-2B cell model. Food Funct 2022; 13:5102-5114. [PMID: 35415734 DOI: 10.1039/d1fo04312a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PM2.5 induces oxidative/antioxidant system imbalance and excessive release of reactive oxygen species (ROS) and produces toxic effects and irreversible damage to the genetic material including chromosomes and DNA. Biochanin A (BCA), an isoflavone with strong antioxidant activity, effectively intervenes against PM2.5-induced oxidative damage. The X-ray repair cross-complementary protein 1 (XRCC1)/BER pathway involves DNA damage repair caused by oxidative stress. This paper aims to explore the mechanism of BCA alleviating oxidative DNA damage caused by PM2.5 by establishing the in vitro cell model based on CRISPR/Cas9 technology and combining it with mechanism pathway research. The results showed that PM2.5 exposure inhibited the expression of BER and NER pathway proteins and induced the overexpression of ERCC1. BCA showed an effective intervention in the toxicity of PM2.5 in normal cells, rather than XRCC1 knock-out cells. This laid a foundation for further exploring the key role of XRCC1 in PM2.5-caused oxidative damage and the BER/DNA damage repair pathway.
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Affiliation(s)
- Yue Yu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Ang Li
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Shihao Li
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Bowen Zheng
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Juan Ma
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Yazhou Liu
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Xiaohong Kou
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
| | - Zhaohui Xue
- School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300350, China.
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Abstract
Base excision repair (BER) is one of the major DNA repair pathways used to fix a myriad of cellular DNA lesions. The enzymes involved in BER, including DNA polymerase β (Polβ), have been identified and characterized, but how they act together to efficiently perform BER has not been fully understood. Through gel electrophoresis, mass spectrometry, and kinetic analysis, we discovered that the two enzymatic activities of Polβ can be interlocked, rather than functioning independently from each other, when processing DNA intermediates formed in BER. The finding prompted us to hypothesize a modified BER pathway. Through conventional and time-resolved X-ray crystallography, we solved 11 high-resolution crystal structures of cross-linked Polβ complexes and proposed a detailed chemical mechanism for Polβ’s 5′-deoxyribose-5-phosphate lyase activity. Base excision repair (BER) is a major cellular pathway for DNA damage repair. During BER, DNA polymerase β (Polβ) is hypothesized to first perform gap-filling DNA synthesis by its polymerase activity and then cleave a 5′-deoxyribose-5-phosphate (dRP) moiety via its dRP lyase activity. Through gel electrophoresis and kinetic analysis of partial BER reconstitution, we demonstrated that gap-filling DNA synthesis by the polymerase activity likely occurred after Schiff base formation but before β-elimination, the two chemical reactions catalyzed by the dRP lyase activity. The Schiff base formation and β-elimination intermediates were trapped by sodium borohydride reduction and identified by mass spectrometry and X-ray crystallography. Presteady-state kinetic analysis revealed that cross-linked Polβ (i.e., reduced Schiff base) exhibited a 17-fold higher polymerase efficiency than uncross-linked Polβ. Conventional and time-resolved X-ray crystallography of cross-linked Polβ visualized important intermediates for its dRP lyase and polymerase activities, leading to a modified chemical mechanism for the dRP lyase activity. The observed interlocking enzymatic activities of Polβ allow us to propose an altered mechanism for the BER pathway, at least under the conditions employed. Plausibly, the temporally coordinated activities at the two Polβ active sites may well be the reason why Polβ has both active sites embedded in a single polypeptide chain. This proposed pathway suggests a corrected facet of BER and DNA repair, and may enable alternative chemical strategies for therapeutic intervention, as Polβ dysfunction is a key element common to several disorders.
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Mubeen M, Khalid MA, Mukhtar M, Sumreen P, Gul T, Ul Ain N, Shahrum S, Tabassum M, Ul-Hamid A, Iqbal A. Elucidating the Size-dependent FRET Efficiency in Interfacially Engineered Quantum Dots attached PBSA Sunscreen. Photochem Photobiol 2022; 98:1017-1024. [PMID: 35092012 DOI: 10.1111/php.13599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 01/24/2022] [Indexed: 11/30/2022]
Abstract
Applying sunscreen on human skin provides photoprotection against the harmful ultraviolet (UV) radiation of the sun. Sunscreen absorbs UV radiations and dissipates the absorbed energy through various radiative and non-radiative pathways. The attachment of functionalized quantum dots (QDs) to the sunscreen component is a novel idea to enhance the absorption cross-section of UV radiations. Therefore, the attachment of the sunscreen component to the ligand functionalized biocompatible QDs and the absorbed energy transfer from sunscreen to the QDs could work as a model system to overall improve the efficiency of the sunscreen. This study elucidates the mechanism of size-dependent Förster resonance energy transfer (FRET) efficiency and its rate between 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and mercaptoacetic acid (MAA) functionalized CdS QDs. In the PBSA-QDs dyad, the PBSA (donor) dissipates UV-absorbed energy to the CdS QDs (acceptor). Following excitation at 306 nm, the steady-state photoluminescence (SSPL) and time-resolved photoluminescence (TRPL) techniques measurements demonstrate that both the non-radiative energy transfer efficiency and rate are QDs size-dependent in addition to donor-acceptor distance, and suggest that bigger sized-QDs result in an increase of the FRET efficiency.
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Affiliation(s)
- Muhammad Mubeen
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | | | - Maria Mukhtar
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | - Poshmal Sumreen
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | - Tehreem Gul
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | - Noor Ul Ain
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | - Saba Shahrum
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | - Mamoona Tabassum
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
| | - Anwar Ul-Hamid
- Core Research Facilities, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi Arabia
| | - Azhar Iqbal
- Department of Chemistry, Quaid-I-Azam University Islamabad-45320, Pakistan
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