Profluorescent PPV-Based Micellar System as a Versatile Probe for Bioimaging and Drug Delivery

Linear and Nonlinear Optical Properties of All-cis and All-trans Poly(p-phenylenevinylene)

Poly(p-phenylenevinylene) (PPV) is a staple of the family of conjugated polymers with desirable optoelectronic properties for applications including light-emitting diodes (LEDs) and photovoltaic devices. Although the significant impact of olefin geometry on the steady-state optical properties of PPVs has been extensively studied, PPVs with precise stereochemistry have yet to be investigated using nonlinear optical spectroscopy for quantum sensing, as well as light harvesting for biological applications. Herein, we report our investigation of the influence of olefin stereochemistry on both linear and nonlinear optical properties through the synthesis of all-cis and all-trans PPV copolymers. We performed two-photon absorption (TPA) using a classical and entangled light source and compared both classical TPA and entangled two-photon absorption (ETPA) cross sections of these stereodefined PPVs. Whereas the TPA cross section of the all-trans PPV was expectedly higher than that of all-cis PPV, presumably because of the larger transition dipole moment, the opposite trend was measured via ETPA, with the all-cis PPV exhibiting the highest ETPA cross section. DFT calculations suggest that this difference might stem from the interaction of entangled photons with lower-lying electronic states in the all-cis PPV variant. Additionally, we explored the photoinduced processes for both cis and trans PPVs through time-resolved fluorescence upconversion and femtosecond transient absorption techniques. This study revealed that the sensitivity of PPVs in two-photon absorption varies with classical versus quantum light and can be modulated through the control of the geometry of the repeating alkenes, which is a key stepping stone toward their use in quantum sensing, bioimaging, and the design of polymer-based light-harvesting systems.

Synthesis and Ring-Opening Metathesis Polymerization of o-Dialkoxy Paracyclophanedienes

The highly strained ortho-diethylhexyloxy [2.2]paracyclophane-1,9-diene (M1) can be synthesized by ring contraction of a dithia[3.3]paracyclophane using a benzyne-induced Stevens rearrangement. This paracyclophanediene undergoes ring-opening metathesis polymerization to give well-defined 2,3-dialkoxyphenylenevinylene polymers with an alternating cis/trans alkene stereochemistry and controllable molecular weight. Fully conjugated block copolymers with electron-rich and electron-deficient phenylene vinylene polymer segments can be prepared by sequential monomer additions. These polymers can be readily isomerized to the all-trans stereochemistry polymer. The optical and electrochemical properties of these polymers were investigated by theory and experiment.

Direct synthesis of light-emitting triblock copolymers from RAFT polymerization

We introduce a straightforward and clean method to synthesize semiconducting triblockcopolymers (tri-BCPs) using RAFT polymerization.

Flash-synthesis of low dispersity PPV via anionic polymerization in continuous flow reactors and block copolymer synthesis

Low dispersity poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)]-1,4-phenylenevinylene (MDMO-PPV) with well-defined end-groups is made available by performing the anionic polymerization in a continuous tubular reactor under flash chemistry conditions.

π-Conjugated nanostructured materials: preparation, properties and photonic applications

This article reviews recent advances in π-conjugated nanostructures based on conjugated oligomers and polymers, focusing on their preparation, energy transfer abilities, optoelectronic and laser applications, and photophysical properties including light harvesting. This is a rapidly evolving field as these materials are expected to have many important applications in areas such as light-emitting diodes, solid-state lighting, photovoltaics, solid-state lasers, biophotonics, sensing, imaging, photocatalysis, and photodynamic therapy. Other advantages of these materials are their versatility, and consequently, their adaptability to diverse fields.

Synthesis and self-seeding behavior of oligo(p-phenylene vinylene)-b-poly(N-(2-hydroxypropyl)methacrylamide)

This article reports the preparation of uniform fiber- and ribbon-like nanostructures via the self-seeding of OPV₅-b-PHPMA diblock copolymers.

Thioalkyl- and sulfone-substituted poly(p-phenylene vinylene)s

Poly(p-phenylene vinylene)s (PPVs) have been studied for decades, but new applications like in bioimaging keep emerging and even simple structural variations are still waiting to be explored, as we highlight by this work.

Organic Bioelectronics: Materials and Biocompatibility

Organic electronic materials have been considered for a wide-range of technological applications. More recently these organic (semi)conductors (encompassing both conducting and semi-conducting organic electronic materials) have received increasing attention as materials for bioelectronic applications. Biological tissues typically comprise soft, elastic, carbon-based macromolecules and polymers, and communication in these biological systems is usually mediated via mixed electronic and ionic conduction. In contrast to hard inorganic semiconductors, whose primary charge carriers are electrons and holes, organic (semi)conductors uniquely match the mechanical and conduction properties of biotic tissue. Here, we review the biocompatibility of organic electronic materials and their implementation in bioelectronic applications.

π-Conjugated Chromophore Incorporated Polystyrene Nanobeads as Single Optical Agent for Three-Channel Fluorescent Probe in Bioimaging Application

Fluorescent polystyrene (PS) nanobeads in the size range ∼70-120 nm incorporating perylene bisimide (PBI-PS) and/or oligo(p-phenylenevinylene) (OPV-PS) was developed by miniemulsion polymerization technique. A dye loading content (DLC) of <3% was sufficient to impart high fluorescence emission capability to the PS beads. OPV-PS exhibited emission in the range 400-550 nm with peak emission at 450 nm (λ_ex = 350 nm; ϕ_FL = 26%); PBI-PS showed emission from 520-650 nm with peak emission at 545 nm (λ_ex = 490 nm; ϕ_FL = 9.7%) in 1× PBS buffer, whereas OPV(PBI)-PS nanobeads incorporating both the fluorophores exhibited multicolor emission capabilities (λ_ex from 350 to 490 nm). The nanoparticles were characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS) for size and zeta potential for surface charge. For bioimaging applications, the PS nanoparticles were incubated with HeLa cells. Cell viability analysis involving HeLa cells showed more than 90% cell viability confirming the biocompatibility of the PS beads. The cellular uptake of the nanoparticles was confirmed by flow cytometry analysis and confocal laser scanning microscopy (CLSM) images. The subcellular localization of the nanoparticles in the cytoplasm could be precisely established by their simultaneous multicolor emission. The PS-based single optical agent presented here that can function as three-channel fluorescent probe to meet the requirements for multicolor bioimaging is advantageous.

Mechanistic investigation of the ring opening metathesis polymerisation of alkoxy and alkyl substituted paracyclophanedienes

This paper discusses the living nature of the ring opening metathesis polymerisation (ROMP) of alkoxy and alkyl substituted [2.2] paracyclophane-1,9-dienes (M1 and M2), initiated with Grubbs’ second and third generation catalysts (G2 and G3).