Water-Soluble Conjugated Polyelectrolytes with Molecular Bumper for Efficient FRET Biosensor
- PDF / 325,595 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 2 Downloads / 161 Views
0965-S10-08
Water-Soluble Conjugated Polyelectrolytes with Molecular Bumper for Efficient FRET Biosensor Han Young Woo1,2, Doojin Vak2, and Guillermo C. Bazan2 1 Nanomaterials Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan, 609-735, Korea, Republic of 2 Chemistry, Institute for Polymers and Organic Solids, UCSB, Santa Barbara, CA, 93106
ABSTRACT We report the design, synthesis and photophysical properties of two new water-soluble conjugated polyelectrolytes, poly(9,9’-bis(6-N,N,N-trimethylammoniumhexyl)fluorene-alt-1,4(2,5-bis(6-N,N,N-trimethylammoniumhexyloxy))phenylene) tetrabromide (P1i) and poly((10,10’-bis(6-N,N,N-trimethylammoniumhexyl)-10H-spiro(anthracene-9,9’-fluorene))-alt1,4-(2,5-bis(6-N,N,N-trimethylammoniumhexyloxy))phenylene) tetrabromide (P2i). They have same electronic conjugation but the main structural difference is the presence of the anthracenyl substituent orthogonal to the polymer main backbone in P2i. Fluorescence resonance energy transfer (FRET) from the two polymers as FRET donors to fluorescein-labeled single stranded DNA (ssDNA-Fl) was studied. It is observed the emission from ssDNA-Fl via FRET by excitation of P2i with a FRET efficiency of ~60%. Fluorescein is not emissive within the ssDNA-Fl/P1i complex. We also observed clear PL quenching (Φ = 0.8 Φ = 0.27) of fluorescein for P2i after electrostatic complexation with ssDNA-Fl. It suggests a quenching pathway of Fl emission through photo-induced charge transfer (PCT) in the electrostatic complex. Both P1i and P2i have same HOMO-LUMO electronic structures and a similar thermodynamic driving force for either FRET or PCT. It appears that PCT operates to a larger extent with P1i, proposing that the presence of the “molecular bumper” in P2i increases Fl emission by increasing the donor-acceptor distance, which decreases more acutely PCT quenching, relative to FRET. INTRODUCTION There has been substantial and growing attention for recent studies using water-soluble conjugated polyelectrolytes as the optical platform in fluorescence-based sensor applications [1,2]. Sensitive and selective sequence-specific DNA detection schemes are urgently needed for immediate infections diagnosis. Various kinds of biosensors using optical and electrochemical transduction schemes have been proposed. Among them, DNA recognition through hybridization are well established, especially homogeneous DNA hybridization assays based on fluorescence resonance energy transfer (FRET) are attractive and constitute one of the most essential detection schemes. One successful DNA sensing method involves the use of cationic conjugated polyelectrolytes (CCPs) and the hybridization between fluorophore-labeled peptide nucleic acids (PNA) and complementary (or non-complementary) target DNA [3]. Electrostatic interactions between CCPs and negatively charged DNA can be coordinated to give rise to efficient FRET and to design sequence-specific DNA assays.
Although there have been made successful demonstrations of FRET-based singlestranded and double-
Data Loading...
