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Boron Doped Carbon Dots with Unusually High Photoluminescence Quantum Yield for Ratiometric Intracellular pH Sensing
Author(s) -
Pal Ayan,
Ahmad Kafeel,
Dutta Deepanjalee,
Chattopadhyay Arun
Publication year - 2019
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201900140
Subject(s) - photoluminescence , boric acid , thiourea , luminescence , boron , quantum yield , citric acid , phosphoric acid , quantum dot , carbon fibers , materials science , nuclear chemistry , chemistry , inorganic chemistry , photochemistry , analytical chemistry (journal) , fluorescence , nanotechnology , organic chemistry , composite number , optoelectronics , physics , quantum mechanics , composite material
Herein we report that boron doping in carbon dots results in increased photoluminescence (PL) quantum yield, which could be used for ratiometric intracellular pH sensing in cancer cell lines. Using a mixture of citric acid monohydrate, thiourea, and boric acid, microwave‐assisted synthesis of boron doped blue emitting carbon dots (B‐Cdots) with an average size of 3.5±1.0 nm was achieved. For B‐Cdots, the maximum quantum yield (QY) was observed to be 25.8 % (11.1 % (w/w) H 3 BO 3 input concentration), whereas, the same was calculated to be 16.9 % and 11.4 % for Cdots (synthesized from citric acid monohydrate and thiourea only) and P‐Cdots (phosphorus doped carbon dots; synthesized using citric acid monohydrate, thiourea and phosphoric acid) (11.1 % (w/w) H 3 PO 4 input concentration), respectively. The observed luminescence efficiencies as obtained from steady state and time‐resolved photoluminescence measurements suggest an alternative emission mechanism due to boron/phosphorus doping in carbon dots. We furthermore demonstrated facile composite formation using B‐Cdots and another carbon dots with orange emission in presence of polyvinyl alcohol (PVA), resulting in white light emission (0.31, 0.32; λ ex 380 nm). The white light emitting composite enabled ratiometric pH sensing in the aqueous medium and showed favorable uptake properties by cancerous cells for intracellular pH sensing as well.