Suzuki Synthesized Polymer Dot Hydrogel with Thermoreversible Fluorescence

The Suzuki linking polymerization method was used to create a sequence of conjugated polymers (CPs) that exhibit red, green, and blue (RGB) fluorescence as per the latest research in the journal Polymers.

Study: Fluorescence Modulation of Conjugated Polymer Nanoparticles Embedded in Poly(N-Isopropylacrylamide) Hydrogel. Image Credit Denis Larkin/

The reprecipitation process was used to make polymer dots (Pdots) from matching CPs, with the Pdot surface-functionalized with an allyl moiety.

As the CP structures were founded on the phenylene group, the Pdots had equal ultraviolet-visible attenuation at 350 nm, suggesting that the same excitation wavelength could be employed.

Pdots were chemically incorporated in poly(N-isopropylacrylamide) (PNIPAM) hydrogel before being used as a thermoresponsive component in the polymer hydrogel. The polymer hydrogel might provide thermally reversible fluorescence changes with RGB emissions hues.

Importance of Conjugated Polymer Nanoparticles

Owing to their distinctive photonic capabilities, conjugated polymer nanoparticles (CPNs) have been effectively synthesized and employed in the biomedical sector in recent years. CPNs' quick growth is mostly due to their simple synthesis techniques and facile separation stages. CPNs have several benefits, including great brightness, outstanding photostability, minimal toxicity, excellent quantum efficiency, and variable surface functionalization.

Environmental Change Detection

The monitoring of environmental factors has received much attention. Polymeric hydrogels that cope with environmental stimuli are gaining popularity due to their beneficial uses in the delivery of drugs, biochemical and biosensors, adsorption, shape control, and color tweaking. Illumination, physical strain, pH, and heat may all change the physical and chemical characteristics of these sensitive polymer hydrogels.

(a) UV-vis and (b) fluorescence spectra of Pdots in water. Excitation wavelength 350 nm.

(a) UV-vis and (b) fluorescence spectra of Pdots in water. Excitation wavelength 350 nm. Image Credit: Namgung, H., Jo, S. & Lee, T. S. 

Advantages of Poly(N-isopropylacrylamide) Hydrogels

Poly(N-isopropylacrylamide) (PNIPAM) is widely recognized amongst hydrogels for its outstanding thermal sensitivity. PNIPAM exhibits a lower critical solution temperature (LCST) of roughly 32 degrees in an aqueous media. Because its polymer chains are completely stretched with random helix shape, the polymer is water-soluble below LCST.

At temperatures over the LCST, PNIPAM shrinks because of the hydrophobic interaction. This property qualifies PNIPAM-based hydrogels for application in drug-delivery systems.

The current research describes thermoresponsive fluorescence tuning of Pdots in a PNIPAM-based hydrogel. Thermally sensitive fluorescence tweaking in the hydrogel with several fluorophores was found achieved different emission colors. To accomplish temperature-dependent fluorescence adjustment, graphene oxide was utilized as a fluorescent quencher.

Polymerization of PNIPAM on the surface of Pdots@AA via emulsion polymerization. Image Credit: Namgung, H., Jo, S. & Lee, T. S. 

Research Findings

Monomers with dibromo units (M1, M2, and M3) were synthesized using techniques described in the literature. Abundant organic solutions, such as CHCl3, dissolved the CPs. GCP had UV-vis absorbing frequencies of 350 nm and fluorescent frequencies of 415 and 490 nm. The solid-state of CP produced findings that were extremely comparable to those obtained in the solutions. BCP, GCP, and RCP fluoresced blue, green, and red at 415, 475, and 633 nm, correspondingly, with an equal wavelength range of 350 nm.

Changes in the (a) hydrodynamic diameters and (b) relative fluorescence intensities (Ix/Ii) of BPdots@PNIPAM (), GPdots@PNAIPAM (), and RPdots@PNAIPAM () in aqueous solution over repeated heating (45 °C) and cooling (25 °C) cycles. di and dx correspond to hydrodynamic diameters at 25 °C and at elevated temperatures, respectively. Ii and Ix correspond to fluorescent intensities (at 415 nm for BPdots@PNAIPAM; 475 nm for GPdots@PNAIPAM; 625 nm for RPdots@PNAIPAM) at 25 °C and at elevated temperature, respectively. Image Credit: Namgung, H., Jo, S. & Lee, T. S. 

The reprecipitation process was used to produce Pdots. Carboxylic acid groups might be formed during Pdot synthesis. The Pdots were disseminated evenly in an aqueous solution without agglomeration, although their UV-vis and emission spectra matched those of their solid states. The zeta capabilities were discovered to be unfavorably attributed to the prevalence of the carboxylic acid group on the Pdot surface.

The hydrodynamic radii of Pdots@PNIPAM decreased with the increase in temperature, regardless of the type of Pdot, with a sharp reduction at around 34 degrees, which is the LCST of PNIPAM, caused by PNIPAM shrinkage.

The fluorescent strength of three Pdots@PNIPAM progressively reduced as temperature increased. The fluorescence intensity of Pdots@PNIPAM over LCST was thought to be disrupted by the shrinking of PNIPAM chains. The contraction of the polymeric chains caused the clustering of Pdots@PNIAPM, resulting in a murky solution.

In summary, BCP, GCP, and RCP were manufactured into Pdots with RGB fluorescent hues after emitting three primary colors via the Suzuki coupling procedure. PSMA was used to surface-functionalize the Pdots with the carboxylic acid group. Over numerous heating/cooling phases, the contraction and fluorescence reduction were bidirectional, demonstrating that Pdots@PNIPAM possessed thermo-responsibility.

Continue reading: Shedding Light on Perovskite Nanocrystal Properties.


Namgung, H., Jo, S. & Lee, T. S., (2021) Fluorescence Modulation of Conjugated Polymer Nanoparticles Embedded in Poly(N-Isopropylacrylamide) Hydrogel. Polymers, 13(24). 4315. Available at:

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Ibtisam Abbasi

Written by

Ibtisam Abbasi

Ibtisam graduated from the Institute of Space Technology, Islamabad with a B.S. in Aerospace Engineering. During his academic career, he has worked on several research projects and has successfully managed several co-curricular events such as the International World Space Week and the International Conference on Aerospace Engineering. Having won an English prose competition during his undergraduate degree, Ibtisam has always been keenly interested in research, writing, and editing. Soon after his graduation, he joined AzoNetwork as a freelancer to sharpen his skills. Ibtisam loves to travel, especially visiting the countryside. He has always been a sports fan and loves to watch tennis, soccer, and cricket. Born in Pakistan, Ibtisam one day hopes to travel all over the world.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Abbasi, Ibtisam. (2021, December 14). Suzuki Synthesized Polymer Dot Hydrogel with Thermoreversible Fluorescence. AZoNano. Retrieved on July 14, 2024 from

  • MLA

    Abbasi, Ibtisam. "Suzuki Synthesized Polymer Dot Hydrogel with Thermoreversible Fluorescence". AZoNano. 14 July 2024. <>.

  • Chicago

    Abbasi, Ibtisam. "Suzuki Synthesized Polymer Dot Hydrogel with Thermoreversible Fluorescence". AZoNano. (accessed July 14, 2024).

  • Harvard

    Abbasi, Ibtisam. 2021. Suzuki Synthesized Polymer Dot Hydrogel with Thermoreversible Fluorescence. AZoNano, viewed 14 July 2024,

Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.