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Conjugated polymer nanoparticles have shown great promise in biological imaging due to their stable optical properties and inert composition but are usually polydispersed. By encapsulating conjugated polymer CN-PPV with a thin silica shell, it is possible to generate photo-stable, nearly monodispersed hollow nanoparticles with tuneable emission.

Conjugated polymers are organic semiconductors that can be used for fluorescence microscopy of living specimens. Here, we report the encapsulation of the bright-red-emitting conjugated polymer, poly[{9,9-dihexyl-2,7-bis(1-cyanovinylene)fluorenylene}-alt-co-{2,5-bis(N,N′-diphenylamino)-1,4-phenylene}] (CN-FO-DPD), and superparamagnetic iron oxide nanoparticles (SPIONs) within poly(styrene-co-maleic anhydride) (PSMA) micelles. The resulting particles exhibited an emission peak at 657 nm, a fluorescence quantum yield of 21%, an average diameter of 65 nm, and a ζ potential of -30 mV. They are taken up by cells, and we describe their use in fluorescence microscopy of living Hela cells and zebrafish embryos and their associated cytotoxicity in HEK, HeLa, and HCE cells.

Conjugated polymer nanoparticles (CPNs) based on a common solar cell material (PTB7) have been prepared, and their potential in theranostic applications based on bioimaging and photosensitizing capabilities has been evaluated. The main absorption and emission bands of the prepared CPNs both fell within the NIR-I (650-950 nm) transparency window, allowing facile and efficient implementation of our CPNs as bioimaging agents, as demonstrated in this work for A549 human lung cancer cell cultures. The prepared CPN samples were also shown to produce reactive oxygen species (ROS) upon photoexcitation in the near-infrared or ultraviolet spectral regions, both in aqueous solutions and in HaCaT keratinocyte cell cultures. Importantly, we show that the photosensitizing ability of our CPNs was largely determined by the nature of the stabilizing shell: coating the CPNs with a Pluronic F-127 copolymer led to an improvement of photoinitiated ROS production, while using poly[styrene-co-maleic anhydride] instead completely quenched said process. This work therefore demonstrates that the photosensitizing capability of CPNs can be modulated via an appropriate selection of stabilizing material and highlights the significance of this parameter for the on-demand design of theranostic probes based on CPNs.

Recent advances in genome engineering have expanded our capabilities to study proteins in their natural states. In particular, the ease and scalability of knocking-in small peptide tags has enabled high throughput tagging and analysis of endogenous proteins. To improve enrichment capacities and expand the functionality of knock-ins using short tags, we developed the tag-assisted split enzyme complementation (TASEC) approach, which uses two orthogonal small peptide tags and their cognate binders to conditionally drive complementation of a split enzyme upon labeled protein expression. Using this approach, we have engineered and optimized the tag-assisted split HaloTag complementation system (TA-splitHalo) and demonstrated its versatile applications in improving the efficiency of knock-in cell enrichment, detection of protein-protein interaction, and isolation of biallelic gene edited cells through multiplexing.

Recent advances in genome engineering have expanded our capabilities to study proteins in their natural states. In particular, the ease and scalability of knocking-in small peptide tags has enabled high throughput tagging and analysis of endogenous proteins. To improve enrichment capacities and expand the functionality of knock-ins using short tags, we developed the tag-assisted split enzyme complementation (TASEC) approach, which uses two orthogonal small peptide tags and their cognate binders to conditionally drive complementation of a split enzyme upon labeled protein expression. Using this approach, we have engineered and optimized the tag-assisted split HaloTag complementation system (TA-splitHalo) and demonstrated its versatile applications in improving the efficiency of knock-in cell enrichment, detection of protein-protein interaction, and isolation of biallelic gene edited cells through multiplexing.

The synthesis of colloidal semiconductor nanocrystals (NCs) from single-source precursors offers simplified manufacturing processes at the cost of reduced atom efficiency. Self-capping routes have the potential to maximise this efficiency although investigation has so far been limited to organic solvents. Here we present the synthesis of copper sulfide NCs via the decomposition of a copper dithiocarbamate complex in water. Nanocrystalline covellite particles were prepared without the need for additional capping ligand and exhibited a hollow nanosphere morphology. Mass spectrometry of the water-stable NCs indicated the presence of a number of surface ligands, including a small amine fragment of the single-source precursor (SSP) complex. A broad plasmon resonance in the near-infrared (NIR) at 990 nm was also observed and the photothermal effect of this demonstrated. Cytotoxicity experiments indicated cell viability remained above 95% for NC concentrations up to 1 mg mL−1, indicating high biocompatibility.

Self-assembling conjugated polymer nanoparticles containing PVKand PLGA-PEG as a matrix polymer were doped with both a luminescentrare-earth complex and magnetic nanoparticles (SPIONs),giving rise to materials that are both luminescent and magnetic.Nanoparticle sizes ranged from 80–110 nm without SPIONs andshowed an increase in size (200–1000 nm) with additional SPIONcontent (11–54%). Quantum yields (QYs) of 24% and 18% weremeasured for systems without and with 11% SPIONs, respectively.Optical properties were stable and suitable for biological imagingapplications.

New materials that exhibit tuneable optical properties, notable emission across the visible spectrum, are of immense interest to biologists as they present a broad palette of colours from a single imaging agent that can be utilised in biological detection. Such a flexible system, when combined with the advantages of using conjugated polymer nanoparticles in cell imaging results in a widely useful medical diagnostic system. Here, we describe tuneable emission observed through oxidation of a conjugated polymer followed by the formation of nanoparticles and their subsequent use in cell imaging.

Red emitting materials are desirable in biology due to the transparency of certain biological tissues at these wavelengths. Here, we report the synthesis of aqueous dispersions of amphiphilic protein (hydrophobin) capped red-emitting cyano-substituted poly(p- phenylenevinylene) conjugated polymer nanoparticles (CPNs) and their use in labeling live mammalian (HeLa) cells.

Post-polymerization modification of the donor–acceptor polymer, poly(9,9-dioctylfluorene-alt-benzothiadiazole), PF8-BT, by electrophilic C–H borylation is a simple method to introduce controllable quantities of near-infrared (near-IR) emitting chromophore units into the backbone of a conjugated polymer. The highly stable borylated unit possesses a significantly lower LUMO energy than the pristine polymer resulting in a reduction in the band gap of the polymer by up to 0.63 eV and a red shift in emission of more than 150 nm. Extensively borylated polymers absorb strongly in the deep red/near-IR and are highly emissive in the near-IR region of the spectrum in solution and solid state. Photoluminescence quantum yield (PLQY) values are extremely high in the solid state for materials with emission maxima ≥ 700 nm with PLQY values of 44% at 700 nm and 11% at 757 nm for PF8-BT with different borylation levels. This high brightness enables efficient solution processed near-IR emitting OLEDs to be fabricated and highly emissive borylated polymer loaded conjugated polymer nanoparticles (CPNPs) to be prepared. The latter are bright, photostable, low toxicity bioimaging agents that in phantom mouse studies show higher signal to background ratios for emission at 820 nm than the ubiquitous near-IR emissive bioimaging agent indocyanine green. This methodology represents a general approach for the post-polymerization functionalization of donor–acceptor polymers to reduce the band gap as confirmed by the C–H borylation of poly((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthien-5-yl)-2,1,3-benzothiadiazole]-2c,2cc-diyl) (PF8TBT) resulting in a red shift in emission of >150 nm, thereby shifting the emission maximum to 810 nm.

Colorectal and prostate cancers are major causes of cancer-related death, with early detection key to increased survival. However, as symptoms occur during advanced stages and current diagnostic methods have limitations, there is a need for new fluorescent probes that remain bright, are biocompatible and can be targeted. Conjugated polymer nanoparticles have shown great promise in biological imaging due to their unique optical properties. We have synthesised small, bright, photo-stable CN-PPV, nanoparticles encapsulated with poloxamer polymer and a thin silica shell. By incubating the CN-PPV silica shelled cross-linked (SSCL) nanoparticles in mammalian (HeLa) cells; we were able to show that cellular uptake occurred. Uptake was also shown by incubating the nanoparticles in RWPE1, WPE1-NB26 and WPE1- NA22 prostate cancer cell lines. Finally, HEK cells were used to show the particles had limited cytotoxicity.