Study of Water Adsorption in Poly(<i>N</i>-isopropylacrylamide) Thin Films Using Fluorescence Emission of 3-Hydroxyflavone Probes

Morris, Cheryl; Szczupak, Bogusław; Klymchenko, Andrey S.; Ryder, Alan G.

doi:10.1021/ma102152j

Cited by 23 publications

(30 citation statements)

References 51 publications

(173 reference statements)

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“…For instance, a 10 μm thick PNIPAm film in an environment with a relative humidity of 90 %RH, was measured to have absorbed 26.5 % by weight of water below the LCST (at 25 C). Above the LCST (at 37 C) the amount of adsorbed/absorbed water was still a very significant 6.1 % by weight [61]. While the water absorption can be described as a purely physical effect, it has consequences for the chemical properties of the polymer because it affects the integral hydrogen bonding within the polymer.…”

Section: Water Sorptionmentioning

confidence: 99%

“…Another very significant environmental factor to consider when dealing with bulk or thin films of thermoresponsive polymers is the issue of water uptake. Many thermoresponsive polymers like PNIPAm are appreciably hydrophilic because of the presence of polar amide groups and will absorb water from the atmosphere [61]. Thus in many cases where one wishes to study the behavior of thermoresponsive polymer thin films one will need to control, or account for the presence of water in the thin films [62].…”

Section: Polymer Characterisation By Fluorescencementioning

confidence: 99%

“…Fluorescent 3-hydroxyflavone (3-HF) derivatives have been used to monitor the infiltration of water in PNIPAm thin films [61]. 3-HF emission is governed by an excited-state intramolecular proton transfer (ESIPT) process and these probes demonstrate very strong solvatochromism and electrochromism [72][73][74].…”

Section: Water Sorptionmentioning

confidence: 99%

“…Analysis of the fluorescence data indicated that water adsorption in the PNIPAm films followed a two-step process: First, at low relative humidity the incoming water molecules disrupted the specific polymer-fluorophore H-bond interaction giving rise to small changes in log(I N* /I T* ) ratios and the overall fluorescence intensity. Then at higher relative humidity (>50 %), as the amount of adsorbed water increases, these intensity parameters change dramatically indicating a larger change in the local polarity of the probe environment [61].…”

Section: Water Sorptionmentioning

confidence: 99%

“…For example, we know that many of the common thermoresponsive polymers are appreciably hygroscopic and will absorb appreciable amounts of water below and above the LCST thus influencing polarity within thin films [61]. The most widely based methods for assessing polarity is based on solvatochromism, and there is an extensive literature on solvent systems.…”

Section: Physicochemical Parameters By Solvatochromismmentioning

confidence: 99%

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Fluorescence Analysis of Thermoresponsive Polymers

Morris

Ryder

2015

Reviews in Fluorescence

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The use of microscale thin polymer films is widespread in biomedical science and engineering, with applications in areas such as tissue engineering, drug delivery, microfluidic devices, bio-adhesion mediators, and bio-actuators. Much attention is devoted to the use of functional polymers that display stimuliresponsive behavior with the intention of providing "smart" coatings. One potential example is the use of thin thermoresponsive polymer films as drug eluting coatings on medical devices, where not only does the polymer function as a drug reservoir but it also acts as a biocompatibility modulator to improve device performance.Often these thin polymer coatings have to be applied to complex geometries, which can cause problems for in-situ analysis. Another important consideration is the fact that these films have large surface area to mass ratios and thus water uptake can be significant. This is serious because coating stability, device efficacy, and long-term storage are influenced by the physiochemical properties of the polymer which are modulated by water content. Thus, there is a need for a rapid, non-contact, non-destructive, analytical method capable of analyzing thermoresponsive polymers in solution, and in-situ of the solid-state on medical devices. Fluorescence spectroscopy based methods can deal with both sample types and provide additional benefits in terms of high sensitivity and low probe concentrations, which provide for minimal sample disruption. This article gives a brief overview of the application of various fluorescence methods for the physicochemical characterization of thermoresponsive polymers such as poly (N-isopropylacrylamide), PNIPAm.

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Section: Water Sorptionmentioning

confidence: 99%

Section: Polymer Characterisation By Fluorescencementioning

confidence: 99%

Section: Water Sorptionmentioning

confidence: 99%

Section: Water Sorptionmentioning

confidence: 99%

Section: Physicochemical Parameters By Solvatochromismmentioning

confidence: 99%

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Fluorescence Analysis of Thermoresponsive Polymers

Morris

Ryder

2015

Reviews in Fluorescence

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Fluorescent Probes Based on Charge and Proton Transfer for Probing Biomolecular Environment

Pivovarenko,

Klymchenko

2023

The Chemical Record

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Fluorescent probes for sensing fundamental properties of biomolecular environment, such as polarity and hydration, help to study assembly of lipids into biomembranes, sensing interactions of biomolecules and imaging physiological state of the cells. Here, we summarize major efforts in the development of probes based on two photophysical mechanisms: (i) an excited‐state intramolecular charge transfer (ICT), which is represented by fluorescent solvatochromic dyes that shift their emission band maximum as a function of environment polarity and hydration; (ii) excited‐state intramolecular proton transfer (ESIPT), with particular focus on 5‐membered cyclic systems, represented by 3‐hydroxyflavones, because they exhibit dual emission sensitive to the environment. For both ICT and ESIPT dyes, the design of the probes and their biological applications are summarized. Thus, dyes bearing amphiphilic anchors target lipid membranes and report their lipid organization, while targeting ligands direct them to specific organelles for sensing their local environment. The labels, amino acid and nucleic acid analogues inserted into biomolecules enable monitoring their interactions with membranes, proteins and nucleic acids. While ICT probes are relatively simple and robust environment‐sensitive probes, ESIPT probes feature high information content due their dual emission. They constitute a powerful toolbox for addressing multitude of biological questions.

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