@article{liu_rong_liu_lindsey_2021, title={Single-Fluorophore Single-Chain Nanoparticle Undergoes Fluorophore-Driven Assembly with Fluorescence Features Retained in Physiological Milieu}, volume={3}, ISSN={["2637-6105"]}, DOI={10.1021/acsapm.0c01313}, abstractNote={To address the longstanding problem of solubilization of hydrophobic fluorophores in aqueous solution, a recent design employed a single fluorophore attached to the terminus of a heterotelechelic, amphiphilic polymer that contained poly(ethylene glycol) (PEG), dodecyl, and sulfonate pendant groups (1:1:5 ratio). The resulting single-polymer–single-fluorophore construct folded in aqueous solution containing 1 M NaCl but is shown here to comprise a mixture of folded (i.e., unimer) and unfolded species in low ionic strength media (e.g., phosphate-buffered saline, PBS) characteristic of physiological milieu. To identify molecular designs that engender unimer formation in PBS solution, heterotelechelic amphiphilic polymers containing cyclododecyl (rather than PEG and dodecyl) and sulfonate pendant groups were synthesized via reversible addition-fragmentation chain-transfer polymerization with variation in (1) degree of polymerization (weight average molecular weight 10–34 kDa) and (2) ratios of pendant groups. A perylene-monoimide or chlorin was used as the hydrophobic fluorophore and attached to the polymer via a maleimide group. Unimer formation occurred quantitatively in PBS solution with polymers of ≥28 kDa, a ratio of cyclododecyl/sulfonate groups of 1:4 to 1:6, and an attached hydrophobic fluorophore. The hydrophobic fluorophore promoted folding of the attached polymer, thereby driving its own encapsulation even in low ionic strength media. The resulting single-chain nanoparticles bearing a single fluorophore in PBS solution retain a fluorescence quantum yield that is at least 70% of that of the hydrophobic fluorophore benchmark alone in a nonpolar solvent. The molecular designs presented herein appear well suited for aqueous solubilization of hydrophobic fluorophores in life science applications.}, number={4}, journal={ACS APPLIED POLYMER MATERIALS}, author={Liu, Sijia and Rong, Jie and Liu, Rui and Lindsey, Jonathan S.}, year={2021}, month={Apr}, pages={1767–1776} }
@article{liu_vairaprakash_lindsey_2019, title={Self-assembly with fluorescence readout in a free base dipyrrin-polymer triggered by metal ion binding in aqueous solution}, volume={43}, ISSN={["1369-9261"]}, DOI={10.1039/c9nj01787a}, abstractNote={Profound morphological and fluorogenic changes ensue upon binding of a zinc ion by two polymers, each of which bears a single dipyrrin at one terminus, forming the bis(dipyrrinato)Zn(ii) complex.}, number={24}, journal={NEW JOURNAL OF CHEMISTRY}, author={Liu, Rui and Vairaprakash, Pothiappan and Lindsey, Jonathan S.}, year={2019}, month={Jun}, pages={9711–9724} }
@article{liu_lindsey_2019, title={Single-Polymer-Single-Cargo Strategy Packages Hydrophobic Fluorophores in Aqueous Solution with Retention of Inherent Brightness}, volume={8}, ISSN={["2161-1653"]}, DOI={10.1021/acsmacrolett.8b00907}, abstractNote={A strategy for encapsulating hydrophobic organic entities in aqueous solution has been developed through use of a self-assembling heterotelechelic amphiphilic random copolymer. The polymer (∼40 kDa), prepared by living radical polymerization, contains orthogonally reactive terminal groups and pendant hydrophobic (dodecyl), nonionic hydrophilic (PEG9), and ionic hydrophilic (sulfonate-terminated) groups. Covalent conjugation of a hydrophobic entity to the polymer terminus has been demonstrated for 8 classes of organic fluorophores. The resulting "pod-fluorophore" architecture is unimeric (∼15 nm in diameter) in aqueous solution with spectral features and fluorescence brightness resembling those of the benchmark fluorophore in organic solution. This strategy separates the functional design of the packaged molecular entity ("cargo") from the often vexing challenge of water solubilization and in so doing creates a unitary (one-pod-one-cargo) platform architecture for potential applications in cytometry, biomedical imaging, environmental sensing, and supramolecular chemistry.}, number={1}, journal={ACS MACRO LETTERS}, author={Liu, Rui and Lindsey, Jonathan S.}, year={2019}, month={Jan}, pages={79–83} }
@article{liu_liu_hood_chen_macnevin_holten_lindsey_2018, title={Chlorophyll-inspired red-region fluorophores: Building block synthesis and studies in aqueous media}, volume={23}, number={1}, journal={Molecules}, author={Liu, R. and Liu, M. R. and Hood, D. and Chen, C. Y. and MacNevin, C. J. and Holten, D. and Lindsey, J. S.}, year={2018} }
@article{taniguchi_hu_liu_du_lindsey_2018, title={Red and near-infrared fluorophores inspired by chlorophylls. Consideration of practical brightness in multicolor flow cytometry and biomedical sciences}, volume={10508}, ISSN={["1996-756X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85047458937&partnerID=MN8TOARS}, DOI={10.1117/12.2302709}, abstractNote={Demands in flow cytometry for increased multiplexing (for detection of multiple antigens) and brightness (for detection of rare entities) require new fluorophores (i.e., "colors") with spectrally distinct fluorescence outside the relatively congested visible spectral region. Flow cytometry fluorophores typically must function in aqueous solution upon bioconjugation and ideally should exhibit a host of photophysical features: (i) strong absorption, (ii) sizable Stokes shift, (iii) modest if not strong fluorescence, and (iv) narrow fluorescence band. Tandem dyes have long been pursued to achieve a large effective Stokes shift, increased brightness, and better control over the excitation and emission wavelengths. Here, the attractive photophysical features of chlorophylls and bacteriochlorophylls – Nature's chosen photoactive pigments for photosynthesis – are described with regards to use in flow cytometry. A chlorophyll (or bacteriochlorophyll) constitutes an intrinsic tandem dye given the red (or near-infrared) fluorescence upon excitation in the higher energy ultraviolet (UV) or visible absorption bands (due to rapid internal conversion to the lowest energy state). Synthetic (bacterio)chlorins are available with strong absorption (near-UV molar absorption coefficient ε(λexc) ~105 M-1cm-1), modest fluorescence quantum yield (Φf = 0.05–0.30), and narrow fluorescence band (10–25 nm) tunable from 600–900 nm depending on synthetic design. The "relative practical brightness" is given by intrinsic brightness [ε(λexc) x Φf] times ηf, the fraction of the fluorescence band that is captured by an emission filter in a multicolor experiment. The spectroscopic features of (bacterio)chlorins are evaluated quantitatively to illustrate practical brightness for this novel class of fluorophores in a prospective 8-color panel.}, journal={REPORTERS, MARKERS, DYES, NANOPARTICLES, AND MOLECULAR PROBES FOR BIOMEDICAL APPLICATIONS X}, publisher={SPIE}, author={Taniguchi, Masahiko and Hu, Gongfang and Liu, Rui and Du, Hai and Lindsey, Jonathan S.}, editor={Achilefu, Samuel and Raghavachari, RameshEditors}, year={2018} }
@article{hu_liu_alexy_mandal_bocian_holten_lindsey_2016, title={Panchromatic chromophore–tetrapyrrole light-harvesting arrays constructed from Bodipy, perylene, terrylene, porphyrin, chlorin, and bacteriochlorin building blocks}, volume={40}, ISSN={1144-0546 1369-9261}, url={http://dx.doi.org/10.1039/C6NJ01782G}, DOI={10.1039/c6nj01782g}, abstractNote={Five new chromophore–tetrapyrrole arrays bearing an ethynyl linker have been synthesized to explore the effects of chromophore nature and tetrapyrrole attachment site on panchromatic spectral properties.}, number={9}, journal={New Journal of Chemistry}, publisher={Royal Society of Chemistry (RSC)}, author={Hu, Gongfang and Liu, Rui and Alexy, Eric J. and Mandal, Amit Kumar and Bocian, David F. and Holten, Dewey and Lindsey, Jonathan S.}, year={2016}, pages={8032–8052} }