Organic Nanocrystals for Nanomedicine and Biophotonics

Baba, Koichi; Kasai, Hitoshi; Nishida, Kohji; Nakanishi, Hachiro

doi:10.5772/10090

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…During the last few decades, extensive efforts have been made in search for suitable semiconductor materials for applications in optoelectronics, solar cell devices, organic light-emitting diodes, field-effect transistors (FETs), gas sensors, wave guides, and many others. − While inorganic materials are in extensive use for these applications, − several important considerations, for example, low cost, ease of syntheses, and excellent optical properties, bring extra advantages in favor of organic semiconductor materials for applications in these devices. ,− In spite of limitations in thermodynamic stability of organic nanomaterials because of weaker binding energy, crystals of polyarenes (polycyclic aromatic hydrocarbons) and their derivatives, known to be good organic semiconductors, have excellent optical and electronic properties. ,− …”

Section: Introductionmentioning

confidence: 99%

Exciton Dynamics in Pyrene and Perylene Nanoaggregates

Manna

Palit

2020

J. Phys. Chem. C

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Photophysical and diffusion properties of excitons generated in perylene and pyrene nanoaggregates have been investigated using steady state as well as time-resolved absorption and emission spectroscopic techniques. The average sizes and heights of the nanoaggregates prepared by the reprecipitation method have been estimated as 120 ± 20 and 60 ± 10 nm, respectively. X-ray diffraction spectra reveal that molecular packing in these nanoaggregates is very similar to that in the α-form (face-to-face pair or dimeric structure) of the crystals, but with possibilities of a large number of disordered regions consisting of monomer molecules. Therefore, following photoexcitation of nanoaggregates, both monomeric and dimeric exciton states are populated. This work, for the first time, could reveal the dynamics of interactions between these two kinds of exciton states, because of which the photophysical and diffusion properties of the excitons are significantly different from those in single crystals. Population yield of the dimeric self-trapped exciton or E state, which is the lowest energy exciton state, is negligibly small via self-trapping of dimeric excitons (dimeric channel) in the <200 ps time domain because of efficient energy transfer from dimeric excitons to monomers. However, the monomeric excitons, which are populated either independently through direct photoexcitation or by energy transfer from the dimeric excitons, contribute to an additional (monomeric) channel populating the E state via energy transfer processes occurring in the nanosecond (ns) time domain. Diffusion coefficients and diffusion lengths of the monomeric excitons estimated in both these nanoaggregates are comparable to those in the β-form of the crystals but much larger than those values reported for the α-form and hence ensure a better or comparable efficiency of energy migration in nanoaggregates as compared to that of single crystals.

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Section: Introductionmentioning

confidence: 99%

Exciton Dynamics in Pyrene and Perylene Nanoaggregates

Manna

Palit

2020

J. Phys. Chem. C

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“…In this context, with the ever increasing importance of polymeric nanocrystals in a variety of domains, accurate prediction of size-dependent melting temperature and enthalpy is of paramount importance. 11,12 We and others have been interested in accessing such thermal transitions by a variety of simulation techniques. [13][14][15][16][17] However, to our knowledge, the atomistic prediction of the melting transition of a polymer crystal is still in its infancy.…”

Section: Introductionmentioning

confidence: 99%

Melting of polymernanocrystals: a comparison between experiments and simulation

Metatla

Palato

Commarieu³

et al. 2012

Soft Matter

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“…Coupling to specifi c biomolecules Not reported Possible [53] Relatively easy bio-conjugation [34,54,55] Cell penetration Easy a) [21] Easy [56] More diffi cult without biomolecule [54] Toxicity Dependent on amount of surfactant and material a) [21] Dependent on amount of surfactant and fl uorophore [57] Very low [58,59] Nonlinear optical properties Not reported σ TPA ≈ 100-2000 GM [53,60] σ TPA ≈ 217-1200 GM [61] …”

Section: Structurementioning

confidence: 99%

Two‐Photon Imaging of a Cellular Line Using Organic Fluorescent Nanoparticles Synthesized by Laser Ablation

Aparicio-Ixta

Alba-Rosales

Ramos‐Ortíz

et al. 2016

Part & Part Syst Charact

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A comparative study of the optical properties of organic fl uorescent nanoparticles fabricated by laser ablation (NPs-LA), reprecipitation (NPs-RP), and microemulsion (NPs-ME) methods is presented. These nanoparticles contain a fl uorene-based p-conjugated molecule (BT2). Distinctive electronic transitions are observed in samples due to the specifi c way in which the molecule BT2 is assembled in each type of nanoparticles; for instance, transitions involved in absorption and emission spectra of NPs-LA result in blueshifting with respect to the molecular solution of BT2, whereas redshifting is observed in NPs-RP and NPs-ME. Further, the results show that under infrared excitation, the aqueous suspensions of NPs-LA exhibit the highest fl uorescence induced by two-photon absorption (≈790 GM at 740 nm), as well as the best photostability, compared with aqueous suspensions of NPs-RP and NPs-ME. The nanoparticles synthetized by the three aforementioned methods are employed as exogenous agents for the visualization of human cervical cancer cell line (HeLa) using confocal and two-photon microscopy. Under similar experimental conditions, it is found that microscopy images of the best quality are obtained with NPs-LA. These results show that laser ablation is a suitable technique for the fabrication of organic fl uorescent nanoparticles used as contrast agents for in vitro fl uorescence microscopy.O-NPs have been successfully exploited as contrast agents (fl uorescent markers) for in vitro and in vivo studies in cellular lines and organisms, [ 5 ] medical imaging, [ 6 ] diagnostic purposes, [ 7 ] and positive confi rmation of the site-specifi c delivery of a drug with the goal of obtaining effective treatment of diseases. [ 8,9 ] Some advantages obtained by using organic nanostructures are: i) stability of fl uorescent organic materials in aqueous suspensions, ii) reduced toxicity, iii) decreased degradation, and iv) selectivity toward specifi c targets.Simple and versatile strategies of fabrication have been used to obtain O-NPs with different morphologies and optical properties in aqueous media. Reprecipitation (RP), [ 10 ] self-assembly, [ 11 ] ion-association, [ 12 ] condensation, [ 13 ] microemulsion (ME), [ 14 ] and laser ablation (LA) [ 15 ] are some methods used to fabricate O-NPs. For the preparation of O-NPs comprising luminescent properties, the most commonly employed methods are RP and ME. [ 16,17 ] LA has also been used to obtain fl uorescent O-NPs, [18][19][20] and some basic characterization of their optical properties has been performed, but to the best of our knowledge, demonstration of their use in the context of biophotonic applications, i.e., imaging of biological samples, has

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Organic Nanocrystals for Nanomedicine and Biophotonics

Cited by 4 publications

References 22 publications

Exciton Dynamics in Pyrene and Perylene Nanoaggregates

Exciton Dynamics in Pyrene and Perylene Nanoaggregates

Melting of polymernanocrystals: a comparison between experiments and simulation

Two‐Photon Imaging of a Cellular Line Using Organic Fluorescent Nanoparticles Synthesized by Laser Ablation

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