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Special Issue "Advanced Photochemistry and Photobiology within Confining Chemical and Biological Hosts"

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Physical Chemistry and Chemical Physics".

Deadline for manuscript submissions: closed (30 September 2019).

Special Issue Editor

Prof. Dr. Abderrazzak Douhal
E-Mail Website
Guest Editor
Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, Campus Tecnolóogico de Toledo, Universidad de Castilla La Mancha (UCLM), Avenida Carlos III, S.N., 45071 Toledo, Spain
Interests: femtochemistry; femtobiology; fhemical and biological confinement effects; nanophotonics; drugs delivery; DSSCs; perovskite solar cells; LEDs; silica-based material composites photochemitry; MOFs; COFs and HOFs photochemistry; single molecule and crystal photoevents; proton transfer; electron transfer energy transfer

Special Issue Information

Dear Colleagues,

Trapped molecules (dye, drugs, and nanoparticles, for example) within chemical and biological pores and cavities show behaviors different from those found in pure solutions. The formed structures or composites are within the field of guest–host complexes. While the observed behavior of the formed structure is relevant to the response and function of many chemical and biological systems, it reflects the degree of confinement of the trapped guests while providing information about the nature of the available nanospace provided by the host. The detected signal gives information on their mutual interactions at the intimate space and time regime. The recent development of laser-based spectroscopy and microscopy techniques, together with those of computational tools, has produced new developments in their molecular science, obtaining deep information on their structure and function in sub-nm femtosecond regimes. Thus, in this Special Issue, we aim to collect contributions from selected players in the field to address the latest advances in terms of where we are and where we can go in “Advanced Photochemistry and Photobiology within Confining Chemical and Biological Hosts”. 

The invited papers will describe the (photo)behavior of selected systems, ranging from dyes to drugs and nanoparticles, encapsulated within hosts, spanning from micelles/liposomes, cycldextrins, proteins/peptides, and silica-based materials, to MOFs. The science of the contributions will focus on the structure and stability of the formed guest–host entities, their spectroscopy and dynamics (form short to long time scale), and these factors’ relevance to their functions and responses to external stimulae. Last but not least, we hope that most of the contributions will address potential scientific and technological applications of their findings, in (but not limited to) chemistry, energy, photonics, sensing, the environment, biology, and drug delivery.

The accepted papers, after a peer reviewing process, will be posted immediately on the website of the International Journal of Molecular Science (IJMS).

Prof. Dr. Abderrazzak Douhal
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. International Journal of Molecular Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. There is an Article Processing Charge (APC) for publication in this open access journal. For details about the APC please see here. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Confinement
  • Guest–host systems
  • Cyclodextrins
  • Micelles
  • Zeolites
  • Mesoporous materials
  • Silica
  • MOFs
  • Nanocavity
  • Nanochannel
  • Photochemistry
  • Spectroscopy
  • Dynamics

Published Papers (5 papers)

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Research

Open AccessArticle
Absorption and Emission Spectroscopic Investigation of the Thermal Dynamics of the Archaerhodopsin 3 Based Fluorescent Voltage Sensor QuasAr1
Int. J. Mol. Sci. 2019, 20(17), 4086; https://doi.org/10.3390/ijms20174086 - 21 Aug 2019
Abstract
QuasAr1 is a fluorescent voltage sensor derived from Archaerhodopsin 3 (Arch) of Halorubrum sodomense by directed evolution. Here we report absorption and emission spectroscopic studies of QuasAr1 in Tris buffer at pH 8. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and [...] Read more.
QuasAr1 is a fluorescent voltage sensor derived from Archaerhodopsin 3 (Arch) of Halorubrum sodomense by directed evolution. Here we report absorption and emission spectroscopic studies of QuasAr1 in Tris buffer at pH 8. Absorption cross-section spectra, fluorescence quantum distributions, fluorescence quantum yields, and fluorescence excitation spectra were determined. The thermal stability of QuasAr1 was studied by long-time attenuation coefficient measurements at room temperature (23 ± 2 °C) and at 2.5 ± 0.5 °C. The apparent melting temperature was determined by stepwise sample heating up and cooling down (obtained apparent melting temperature: 65 ± 3 °C). In the protein melting process the originally present protonated retinal Schiff base (PRSB) with absorption maximum at 580 nm converted to de-protonated retinal Schiff base (RSB) with absorption maximum at 380 nm. Long-time storage of QuasAr1 at temperatures around 2.5 °C and around 23 °C caused gradual protonated retinal Schiff base isomer changes to other isomer conformations, de-protonation to retinal Schiff base isomers, and apoprotein structure changes showing up in ultraviolet absorption increase. Reaction coordinate schemes are presented for the thermal protonated retinal Schiff base isomerizations and deprotonations in parallel with the dynamic apoprotein restructurings. Full article
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Open AccessArticle
Contact Lenses Delivering Nitric Oxide under Daylight for Reduction of Bacterial Contamination
Int. J. Mol. Sci. 2019, 20(15), 3735; https://doi.org/10.3390/ijms20153735 - 31 Jul 2019
Abstract
Ocular infection due to microbial contamination is one of the main risks associated with the wearing of contact lens, which demands novel straightforward strategies to find reliable solutions. This contribution reports the preparation, characterization and biological evaluation of soft contact lenses (CL) releasing [...] Read more.
Ocular infection due to microbial contamination is one of the main risks associated with the wearing of contact lens, which demands novel straightforward strategies to find reliable solutions. This contribution reports the preparation, characterization and biological evaluation of soft contact lenses (CL) releasing nitric oxide (NO), as an unconventional antibacterial agent, under daylight exposure. A tailored NO photodonor (NOPD) was embedded into commercial CL leading to doped CL with an excellent optical transparency (transmittance = 100%) at λ ≥ 450 nm. The NOPD results homogeneously distributed in the CL matrix where it fully preserves the photobehavior exhibited in solution. In particular, NO release from the CL and its diffusion in the supernatant physiological solution is observed upon visible light illumination. The presence of a blue fluorescent reporting functionality into the molecular skeleton of the NOPD, which activates concomitantly to the NO photorelease, allows the easy monitoring of the NO delivery in real-time and confirms that the doped CL work under daylight exposure. The NO photoreleasing CL are well-tolerated in both dark and light conditions by corneal cells while being able to induce good growth inhibition of Staphylococcus aureus under visible light irradiation. These results may pave the way to further engineering of the CL with NOPD as innovative ocular devices activatable by sunlight. Full article
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Open AccessArticle
Protein Engineering of Dual-Cys Cyanobacteriochrome AM1_1186g2 for Biliverdin Incorporation and Far-Red/Blue Reversible Photoconversion
Int. J. Mol. Sci. 2019, 20(12), 2935; https://doi.org/10.3390/ijms20122935 - 15 Jun 2019
Abstract
Cyanobacteria have cyanobacteriochromes (CBCRs), which are photoreceptors that bind to a linear tetrapyrrole chromophore and sense UV-to-visible light. A recent study revealed that the dual-Cys CBCR AM1_1186g2 covalently attaches to phycocyanobilin and exhibits unique photoconversion between a Pr form (red-absorbing dark state, λ [...] Read more.
Cyanobacteria have cyanobacteriochromes (CBCRs), which are photoreceptors that bind to a linear tetrapyrrole chromophore and sense UV-to-visible light. A recent study revealed that the dual-Cys CBCR AM1_1186g2 covalently attaches to phycocyanobilin and exhibits unique photoconversion between a Pr form (red-absorbing dark state, λmax = 641 nm) and Pb form (blue-absorbing photoproduct, λmax = 416 nm). This wavelength separation is larger than those of the other CBCRs, which is advantageous for optical tools. Nowadays, bioimaging and optogenetics technologies are powerful tools for biological research. In particular, the utilization of far-red and near-infrared light sources is required for noninvasive applications to mammals because of their high potential to penetrate into deep tissues. Biliverdin (BV) is an intrinsic chromophore and absorbs the longest wavelength among natural linear tetrapyrrole chromophores. Although the BV-binding photoreceptors are promising platforms for developing optical tools, AM1_1186g2 cannot efficiently attach BV. Herein, by rationally introducing several replacements, we developed a BV-binding AM1_1186g2 variant, KCAP_QV, that exhibited reversible photoconversion between a Pfr form (far-red-absorbing dark state, λmax = 691 nm) and Pb form (λmax = 398 nm). This wavelength separation reached 293 nm, which is the largest among the known phytochrome and CBCR photoreceptors. In conclusion, the KCAP_QV molecule developed in this study can offer an alternative platform for the development of unique optical tools. Full article
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Open AccessArticle
Single Crystal FLIM Characterization of Clofazimine Loaded in Silica-Based Mesoporous Materials and Zeolites
Int. J. Mol. Sci. 2019, 20(12), 2859; https://doi.org/10.3390/ijms20122859 - 12 Jun 2019
Abstract
Clofazimine (CLZ) is an effective antibiotic used against a wide spectrum of Gram-positive bacteria and leprosy. One of its main drawbacks is its poor solubility in water. Silica based materials are used as drug delivery carriers that can increase the solubility of different [...] Read more.
Clofazimine (CLZ) is an effective antibiotic used against a wide spectrum of Gram-positive bacteria and leprosy. One of its main drawbacks is its poor solubility in water. Silica based materials are used as drug delivery carriers that can increase the solubility of different hydrophobic drugs. Here, we studied how the properties of the silica framework of the mesoporous materials SBA-15, MCM-41, Al-MCM-41, and zeolites NaX, NaY, and HY affect the loading, stability, and distribution of encapsulated CLZ. Time-correlated single-photon counting (TCSPC) and fluorescence lifetime imaging microscopy (FLIM) experiments show the presence of neutral and protonated CLZ (1.3–3.8 ns) and weakly interacting aggregates (0.4–0.9 ns), along with H- and J-type aggregates (<0.1 ns). For the mesoporous and HY zeolite composites, the relative contribution to the overall emission spectra from H-type aggregates is low (<10%), while for the J-type aggregates it becomes higher (~30%). For NaX and NaY the former increased whereas the latter decreased. Although the [email protected] composites show higher loading compared to the [email protected] ones, the behavior of CLZ is not uniform and its dynamics are more heterogeneous across different single mesoporous particles. These results may have implication in the design of silica-based drug carriers for better loading and release mechanisms of hydrophobic drugs. Full article
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Open AccessArticle
Confinement Effect of Micro- and Mesoporous Materials on the Spectroscopy and Dynamics of a Stilbene Derivative Dye
Int. J. Mol. Sci. 2019, 20(6), 1316; https://doi.org/10.3390/ijms20061316 - 15 Mar 2019
Abstract
Micro- and mesoporous silica-based materials are a class of porous supports that can encapsulate different guest molecules. The formation of these hybrid complexes can be associated with significant alteration of the physico-chemical properties of the guests. Here, we report on a photodynamical study [...] Read more.
Micro- and mesoporous silica-based materials are a class of porous supports that can encapsulate different guest molecules. The formation of these hybrid complexes can be associated with significant alteration of the physico-chemical properties of the guests. Here, we report on a photodynamical study of a push–pull molecule, trans-4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), entrapped within faujasite-type zeolites (HY, NaX, and NaY) and MCM-41 in dichloromethane suspensions. The complex formation gives rise to caged monomers and H- and J-aggregates. Steady-state experiments show that the nanoconfinement provokes net blue shifts of both the absorption and emission spectra, which arise from preferential formation of H-aggregates concomitant with a distortion and/or protonation of the DCM structure. The photodynamics of the hybrid complexes are investigated by nano- to picosecond time-resolved emission experiments. The obtained fluorescence lifetimes are 65–99 ps and 350–400 ps for H- and J-aggregates, respectively, while those of monomers are 2.46–3.87 ns. Evidences for the presence of a charge-transfer (CT) process in trapped DCM molecules (monomers and/or aggregates) are observed. The obtained results are of interest in the interpretation of electron-transfer processes, twisting motions of analogues push–pull systems in confined media and understanding photocatalytic mechanisms using this type of host materials. Full article
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