Indrajit Srivastava1, Santosh K Misra1, Sushant Bangru2,3, Kingsley A Boateng4, Julio A N T Soares5, Aaron S Schwartz-Duval1, Auinash Kalsotra4,2,3, Dipanjan Pan1,6,7. 1. Departments of Bioengineering, Materials Science and Engineering and Beckman Institute, Mills Breast Cancer Institute, and Carle Foundation Hospital, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States. 2. Department of Biochemistry, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, United States. 3. Cancer Center at Illinois, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, United States. 4. Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States. 5. Frederick Seitz Materials Research Laboratories Central Facilities, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States. 6. Departments of Diagnostic Radiology and Nuclear Medicine and Pediatrics, University of Maryland Baltimore, Health Sciences Facility III, 670 W Baltimore Street, Baltimore, Maryland 21201, United States. 7. Department of Chemical, Biochemical, and Environmental Engineering, Interdisciplinary Health Sciences Facility, University of Maryland Baltimore, 1000 Hilltop Circle, Baltimore, Maryland, 21250, United States.
Abstract
By using complementary DNA sequences as surface ligands, we selectively allow two individual diffusing "dual-color" carbon dots to interact in situ and in vitro. Spontaneous nanoscale oxidation of surface-abundant nitroso-/nitro-functionalities leads to two distinctly colored carbon dots (CD) which are isolated by polarity driven chromatographic separation. Green- and red-emitting carbon dots (gCD and rCD) were decorated by complementary single-stranded DNAs which produce a marked increase in the fluorescence emission of the respective carbon dots. Mutual colloidal interactions are achieved through hybridization of complementary DNA base pairs attached to the respective particles, resulting in quenching of their photoluminescence. The observed post-hybridization quenching is presumably due to a combined effect from an aggregation of CDs post duplex DNA formation and close proximity of multicolored CDs, having overlapped spectral regions leading to a nonradiative energy transfer process possibly released as heat. This strategy may contribute to the rational design of mutually interacting carbon dots for a better control over the resulting assembly structure for studying different biological phenomenon including molecular cytogenetics. One of the newly synthesized CDs was successfully used to image intracellular location of GAPDH mRNA using an event of change in fluorescence intensity (FI) of CDs. This selectivity was introduced by conjugating an oligonucleotide harboring complementary sequence to GAPDH mRNA. FI of this conjugated carbon dot, rCD-GAPDH, was also found to decrease in the presence of Ca2+, varied in relation to H+ concentrations, and could serve as a tool to quantify the intracellular concentrations of Ca2+ and pH value (H+) which can give important information about cell survival. Therefore, CD-oligonucleotide conjugates could serve as efficient probes for cellular events and interventions.
By using complementary DNA sequences as surface ligann class="Chemical">ds, we selectively allow two individual diffusing "dual-color" carbon dots to interact in situ and in vitro. Spontaneous nanoscale oxidation of surface-abundant nitroso-/nitro-functionalities leads to two distinctly colored carbon dots (CD) which are isolated by polarity driven chromatographic separation. Green- and red-emitting carbon dots (gCD and rCD) were decorated by complementary single-stranded DNAs which produce a marked increase in the fluorescence emission of the respective carbon dots. Mutual colloidal interactions are achieved through hybridization of complementary DNA base pairs attached to the respective particles, resulting in quenching of their photoluminescence. The observed post-hybridization quenching is presumably due to a combined effect from an aggregation of CDs post duplex DNA formation and close proximity of multicolored CDs, having overlapped spectral regions leading to a nonradiative energy transfer process possibly released as heat. This strategy may contribute to the rational design of mutually interacting carbon dots for a better control over the resulting assembly structure for studying different biological phenomenon including molecular cytogenetics. One of the newly synthesized CDs was successfully used to image intracellular location of GAPDH mRNA using an event of change in fluorescence intensity (FI) of CDs. This selectivity was introduced by conjugating an oligonucleotide harboring complementary sequence to GAPDH mRNA. FI of this conjugated carbon dot, rCD-GAPDH, was also found to decrease in the presence of Ca2+, varied in relation to H+ concentrations, and could serve as a tool to quantify the intracellular concentrations of Ca2+ and pH value (H+) which can give important information about cell survival. Therefore, CD-oligonucleotide conjugates could serve as efficient probes for cellular events and interventions.
Authors: Santosh K Misra; Indrajit Srivastava; John S Khamo; Vishnu V Krishnamurthy; Dinabandhu Sar; Aaron S Schwartz-Duval; Julio A N T Soares; Kai Zhang; Dipanjan Pan Journal: Nanoscale Date: 2018-08-23 Impact factor: 7.790
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