Synthesis, characterization, and energy transfer studies of dye-labeled poly(butyl methacrylate) latex particles prepared by miniemulsion polymerization

Design, synthesis, and spectroscopic profiling of novel coumarin dyes: Investigating solvent sensitivity and photophysical properties

Coumarin dyes are highly versatile and widely employed as fluorescent chemosensors in a variety of fields, including molecular imaging, bioorganic chemistry, analytical chemistry, materials chemistry, biology, and medical science. Thanks to their outstanding photostability and high quantum yield, they represent an ideal choice for developing sensitive and selective sensing platforms. In this study, we successfully designed and synthesized four new dyes based on the coumarin dye molecular skeleton, investigating their solvent sensitivity and spectroscopic properties. Our novel coumarin dyes were synthesized by a straightforward approach, reacting coumarin-3-carboxylic acid succinimidyl ester derivatives with corresponding amines in 1,4-dioxane as a solvent. We carefully monitored the completion of the reactions using thin-layer chromatography (TLC) and characterized these dyes using spectral and elemental analyses. We further investigated the UV, fluorescence, time-correlated single photon counting (TCSPC) technique and time-resolved spectroscopy (TRES) of these dyes in different solvents and on polymer film poly(methyl methacrylate) (PMMA). The quantum yield of the synthesized dyes was determined, with values observed to range between 0.55 and 0.94. Most of the dye-solvent and dye-polymer combinations exhibited single exponential decay, with lifetimes ranging from 2.3 to 3 ns. Minor deviations from single exponential behavior were observed for most of the dyes in toluene, while significant deviations were observed for coumarin dyes with piperazine moiety. We have provided a rationalization of these results in terms of the chemical functionalities of the various dyes. Furthermore, we investigated the effect of interactions between 7-methoxy-2-oxo-N-(2-(piperazin-1-yl)ethyl)-2H-chromene-3-carboxamide and silica nanoparticles (Ludox) on the spectroscopic properties of these dyes, with charge transfer being one possible mechanism contributing to the behavior of the dyes. Additionally, we explored the effect of trifluoroacetic acid (TFA) on the dyes' emission intensity and fluorescence decay. Based on our UV and fluorescence measurements of the dyes in different solvents, we have concluded that these dyes can create excellent donor-acceptor pairs for our upcoming fluorescence resonance energy transfer (FRET) experiments.

Thiol-Functional Polymer Nanoparticles via Aerosol Photopolymerization

Spherical, individual polymer nanoparticles with functional -SH groups were synthesized via aerosol photopolymerization (APP) employing radically initiated thiol-ene chemistry. A series of various thiol and alkene monomer combinations were investigated based on di-, tri-, and tetrafunctional thiols with difunctional allyl and vinyl ethers, and di- and trifunctional acrylates. Only thiol and alkene monomer combinations able to build cross-linked poly(thio-ether) networks were compatible with APP, which requires fast polymerization of the generated droplet aerosol during the photoreactor passage within a residence time of half-minute. Higher monomer functionalities and equal overall stoichiometry of functional groups resulted in the best nanoparticles being spherical and individual, proven by scanning electron microscopy (SEM). The presence of reactive -SH groups in the synthesized nanoparticles as a basis for post-polymerization modifications was verified by Ellman's test.

Light and latex: advances in the photochemistry of polymer colloids

Unparalleled temporal and spatial control of colloidal chemical processes introduces immense potential for the manufacturing, modification, and manipulation of latex particles.

Natural biodegradable polymers based nano-formulations for drug delivery: A review

Nanomedicines are now considered as the new-generation medication in the current era mainly because of their features related to nano size. The efficacy of many drugs in their micro/macro formulations is shown to have poor bioavailability and pharmacokinetics after oral administration. To overcome this predicament, use of natural/synthetic biodegradable polymeric nanoparticles (NPs) have gained prominence in the field of nanomedicine for targeted drug delivery to improve biocompatibility, bioavailability, safety, enhanced permeability, better retention time and lower toxicity. For drug delivery, it is essential to have biodegradable nanoparticle formulations for safe and efficient transport and release of drug at the intended site. Moreover, depending on the target organ, a suitable biodegradable polymer can be selected as the drug-carrier for target specific as well as for sustained drug delivery. The aim of this review is to present the current status and scope of natural biodegradable polymers as well as some emerging polymers with special characteristics as suitable carriers for drug delivery applications. The most widely preferred preparation methods are discussed along with their characterization using different analytical techniques. Further, the review highlights significant features of methods developed using natural polymers for drug entrapment and release studies.

Streptavidin conjugation and quantification-a method evaluation for nanoparticles

Aiming at the development of validated protocols for protein conjugation of nanomaterials and the determination of protein labeling densities, we systematically assessed the conjugation of the model protein streptavidin (SAv) to 100-, 500-, and 1000-nm-sized polystyrene and silica nanoparticles and dye-encoded polymer particles with two established conjugation chemistries, based upon achievable coupling efficiencies and labeling densities. Bioconjugation reactions compared included EDC/sulfo NHS ester chemistry for direct binding of the SAv to carboxyl groups at the particle surface and maleimide-thiol chemistry in conjunction with heterobifunctional PEG linkers and aminated nanoparticles (NPs). Quantification of the total and functional amounts of SAv on these nanomaterials and unreacted SAv in solution was performed with the BCA assay and the biotin-FITC (BF) titration, relying on different signal generation principles, which are thus prone to different interferences. Our results revealed a clear influence of the conjugation chemistry on the amount of NP crosslinking, yet under optimized reaction conditions, EDC/sulfo NHS ester chemistry and the attachment via heterobifunctional PEG linkers led to comparably efficient SAv coupling and good labeling densities. Particle size can obviously affect protein labeling densities and particularly protein functionality, especially for larger particles. For unstained nanoparticles, direct bioconjugation seems to be the most efficient strategy, whereas for dye-encoded nanoparticles, PEG linkers are to be favored for the prevention of dye-protein interactions which can affect protein functionality specifically in the case of direct SAv binding. Moreover, an influence of particle size on achievable protein labeling densities and protein functionality could be demonstrated.

Preparation and properties of a novel polymerizable amphiphilic anthraquinone derivative and its cationic colored copolymer latexes

Polymerizable amphiphilic dye was synthesized and used to prepare colored copolymer latexes. The amphiphilic structure overcomes the solubility limitation, dye conversion and color depth. The covalently colored film has enhanced light fastness.

The Effect of Multidentate Biopolymer Based on Polyacrylamide Grafted onto Kappa-Carrageenan on the Spectrofluorometric Properties of Water-Soluble CdS Quantum Dots

A new fluorescent composite based on CdS quantum dots immobilized on the multidentate biopolymer matrix is prepared through the graft copolymerization of the acrylamide onto kappa-Carrageenan. A variety of techniques like thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) was used to confirm the structure of the obtained samples. To investigate the spectrofluorometric properties, fluorescence spectroscopy of the obtained quantum dots was studied.