Amino Acid Groups Enable Electrosynthesized Polyfluorenes to Specifically Recognize Cr₂O₇^2–

Abstract

The unique “molecular wire effect” property of conjugated polymers (CPs) enables them to own signal amplification. Therefore, they are good candidates for constructing fluorescent sensors with high sensitivity. In this work, two water-soluble polyfluorene derivatives P­(Fmoc-Arg-OH) and P­(Fmoc-Glu-OH) were synthesized using electrochemical polymerization in boron trifluoride diethyl etherate–trifluoroacetic systems. Absorption and emission spectra showed that the two polymers were blue emitters. In order to specifically target dichromate ions (Cr2O7 2–), we introduced amino acid groups in the side chain of the two polymers. A series of selective and competitive experiments in a pH = 7.00 PBS solution showed that both polymers had high selectivity toward Cr2O7 2–. Thanks to their signal amplification effect, the limits of detection of P­(Fmoc-Arg-OH) and P­(Fmoc-Glu-OH) could reach 16.67 pM and 3.33 μM, respectively. All results showed that CPs are a good platform for designing fluorescent sensors with high selectivity and sensitivity.

High-Quality Conjugated Polymers Achieving Ultra-Trace Detection of Cr2O72− in Agricultural Products

“…As shown in Figure 2, as the number of scan cycles increased, the current density of a pair of reversible redox peaks in cyclic voltammograms (CVs) increased, indicating that monomers Fmoc-Ala-OH and Fmoc-Thr-OH can be electropolymerized in BFEE. By analysing the 1 H NMR spectra (Figures S1 and S2), it was found that two molecules were polymerized at the position 2,7, which was the same as other fluorene derivatives [13][14][15]31]. From GPC results, polymers P(Fmoc-Ala-OH) and P(Fmoc-Thr-OH) contained 72 and 41 repeat units, respectively.…”

“…In other words, the two polymers have high polymerization degrees. Combined with other polyfluorene reported by our groups [12][13][14][15], the shorter side chain groups will reduce the polymerization hindrance of fluorene. Importantly, high polymerization degrees are beneficial to the detection sensitivity in application.…”

“…Chromium (Cr) is one necessary element in industry, but the impact of hexavalent chromium (Cr(VI)) on human health should not be underestimated [10][11][12]. Once its Molecules 2022, 27, 4294 2 of 8 content exceeds the standard in water (existing in the form of Cr 2 O 7 2− ), it will be enriched in the crops and passed to the human body through the food chain, which will cause various diseases [13][14][15][16][17][18][19]. Up to now, Cr 2 O 7 2− detection materials mainly contain inorganic materials (quantum dots [20][21][22] and carbon dots [23][24][25]), organic materials (organic molecules [26,27] and CPs [28]), and organic-inorganic hybrid materials (metal-organic frameworks [29,30] and nanoclusters).…”

“…Unfortunately, few efforts have been devoted to the development of this kind of sensor based on CPs, which may be the difficulties of design and preparation. Our group have been committed to the design and development of new CPs and apply them in fluorescent sensing fields [12][13][14][15]. Indeed, CPs exhibit supersensitivity in detecting targets.…”

A water-soluble conjugated polyelectrolyte for selective and sensitive detection of carcinogenic chromium(vi)

“…49 Recently they have been explored in the Cr(VI) detection. 13,50 Yet detailed optical sensing mechanistic insights and affordable sensing platforms like paper test strips remain quite challenging. Herein, we report the synthesis of a water-soluble conjugated polyelectrolyte PPMI and its application as a fluorescence sensor for the detection of carcinogenic Cr(VI) in aqueous media and on a solid support.…”