Background/Objectives: Covalent conjugation of an antibiotic vancomycin (VCM) moiety and a photosensitizing mesochlorin (mChlPd) unit into one molecular entity may present the potential to produce the combinatorial effect of both antibacterial photodynamic therapeutic (aPDT) and antibiotic activities. Our recent study indicated that a short linkage of <4 (C-C/or C-N) bond distances between these two moieties resulted in significant steric hindrance due to the bulky VCM, which greatly reduces the accessibility of the agent to the cell surface of methicillin-resistant Staphylococcus aureus (MRSA). The observed aPDT efficacy was found to be minimal. Here, we report that the revision of this linkage, via an EG10 unit using identical synthetic procedures, was able to resolve the issue. Methods: Accordingly, the corresponding combinatorial aPDT-antibiotic compound, consisting of two covalently bonded quaternary ammonium pentacationic arms on the mesochlorin chromophore core, designated as VCMe-mChlPd-N10+ (LC40e+), was prepared for applications in antibacterial photodynamic inactivation (aPDI) activity. It was selected to investigate its enhanced binding and targeting ability to the surface of Gram-positive MRSA cells. Subsequent antibacterial photodynamic therapeutic (aPDT) activity to inactivate MRSA was investigated to substantiate the corresponding cell-surface binding effect on the efficacy of aPDT. Results: We found that the covalent combination of 10 positive charges and an MRSA-targeting vancomycin (VCM) moiety in a conjugated structure, functioning as an antibiotic-decacationic photosensitizing agent (Abx-dcPS), was capable of largely improving the MRSA cell-targeting efficiency. Importantly, variation in the chain length of the oligo(ethylene glycol) linker of VCMe-mChlPd-N10+, which was sufficiently long enough to properly separate the photoactive mesochlorin ring moiety from the VCM moiety within the molecular structure, resulted in significantly enhanced aPDT activity. The new conjugate provided nearly complete eradication (>6.5-log10 colony-forming units (CFU) reduction) of MRSA cells in vitro. The aPDT efficacy followed the order Abx-dcPS (combinatorial decacationic) > dcPS (decacationic) >> nPS (nonionic). This order was also verified by the relative physical binding trend of these PSs using either nPS-, dcPS-, or Abx-dcPS-pretreated and pre-fixed MRSA cells in investigations of fluorescent confocal microscopy, UV-vis fluorescence spectroscopy, and transmission electron microscopy (TEM). Conclusions: Furthermore, the molecular conjugate of Abx-dcPS may provide covalent co-delivery of two drug components concurrently, which might also serve as an effective antibiotic agent after aPDT and potentially prevent the reoccurrence of MRSA-induced infection.

Based on the reactive force-field (ReaxFF) molecular dynamics, the thermostability of cross-linked and non-cross-linked phenolic was compared to study the effect of cross-linked and branched structures on the pyrolysis mechanism. The results show that during the pyrolysis process, phenolic tends to break into low-boiling molecules with less than 4 carbon atoms and polymerizes into macromolecules with more than 1500 carbon atoms. The results of residual carbon rate and products distribution confirm that carbon skeleton of phenolic resin with high degree of crosslinking and branching is better preserved and has better thermostability. The reaction kinetics path of phenolic pyrolysis was reasonably summarized, revealing the generation mechanism of low-boiling molecules with less than 4 carbon atoms and large carbon clusters, which is in good agreement with the experimental results of activation energy and chemical bond energy. The reaction kinetics data obtained in this work provide a reliable basis for multi-scale reaction simulation.(c) 2023 Elsevier Ltd. All rights reserved.

Utilization of [60]fullerosome monolayer grafting approach on both sides of graphene nanosheets giving the corresponding sandwiched nanostructures was demonstrated as a key intermediate for the con...

Selective separation of 1-C4H8 and 2-C4H8 isomers is of great importance and daunting challenge in petrochemical industries due to that these isomers differ only by the position of the double bond....

3D-configurated donor-acceptor stereoisomers cis-cup-tris[C 60 >(DPAF-C 9 )] were found to exhibit photoswitchable dielectric amplification phenomena using white LED light excitation at GHz frequency. The observation was correlated to the photoactivation of the Au-layer resulting in plasmonic energy to enhance photoinduced intramolecular e - -transfer from DPAF to a C 60 > moiety. Accumulated plasmonic resonance energy at the near-field surface was effective to distribute negative charges along the outer (C 60 >)-derived fullerosome shell layer of the trilayered NPs.

New 3D conformers were synthesized to show a nanomolecular configuration with geometrically branched 2-diphenylaminofluorene (DPAF-C2M) chromophores using a symmetrical 1,3,5-triaminobenzene ring as the center core for the connection of three fused DPAF-C2M moieties. The design led to a class of cis-cup-tris[(DPAF-C2M)-C60(>DPAF-C9)] 3D conformers with three bisadduct-analogous cages per nanomolecule facing at the same side of the geometrical molecular cis-cup-shape structure. A sequential synthetic route was described to afford this 3D configurated conformer in a high yield with various spectroscopic characterizations. In principle, a nanostructure with a non-coplanar 3D configuration in design should minimize the direct contact or π-stacking of fluorene rings with each other during molecular packing to the formation of fullerosome array. It may also prevent the self-quenching effect of its photoexcited states in solids. Photophysical properties of this cis-cup-conformer were also investigated.

It is known that multiple cationic charges are required to produce broad-spectrum antimicrobial photo-sensitizers (PS) for photodynamic inactivation (aPDI) or photodynamic therapy of bacteria and fungi. In the present study we describe the synthesis and aPDI testing of a set of derivatives prepared from the parent pheophytin molecule with different numbers of attached side arms (1–3) each consisting of five quaternized cationic groups (pentacationic), producing the corresponding [Zn 2+ ]pheophorbide- a -N (C 2 N + C 1 C 3 ) 5 (Zn-Phe-N 5 + , 5 charges), [Zn 2+ ]chlorin e 6 -[N(C 2 N + C 1 C 3 ) 5 ] 2 (Zn-Chl-N 10 + , 10 charges) and [Zn 2+ ]mesochlorin e 6 -[N(C 2 N + C 1 C 3 ) 5 ] 3 (Zn- m Chl-N 15 + , 15 charges). Moreover, a conjugate between Zn-Phe-N 5 + and the antibiotic vancomycin called Van-[Zn 2+ ]- m -pheophorbide-N(C 2 N + C 1 C 3 ) 5 (Van-Zn- m Phe-N 5 + ) was also prepared. The aPDI activities of all compounds were based on Type-II photochemistry ( 1 O 2 generation). We tested these compounds against Gram-positive methicillin-resistant Staphylococcus aureus (MRSA), Gram-negative Escherichia coli , and the fungal yeast Candida albicans. All three compounds were highly active against MRSA, giving eradication (≥6 logs of killing) with <1.0 µM and 10 J cm −2 of 415 nm light. The order of activity was Zn-Phe-N 5 + > Zn-Chl-N 10 + > Zn- m Chl-N 15 + . In the case of E coli the activity was much lower (eradication was only possible with 50 µM Zn- m Chl-N 15 + and 20 J cm −2 ). The order of activity was the reverse of that found with MRSA (Zn- m Chl-N 15 + > Zn-Chl-N 10 + > Zn-Phe-N 5 + ). Activity against C. albicans was similar to E. coli with Zn- m Chl-N 15 + giving eradication. The activity of Van-Zn- m Phe-N 5 + was generally lower than that of Zn-Phe-N 5 + (except for E. coli ). Red (660 nm) light was also effective as might be expected from the absorption spectra. An initial finding that Van-Zn- m Phe-N 5 + might have higher activity against vancomycin resistant Enterococcus fecium (VRE) strains (compared to vancomycin sensitive strains) was disproved when it was found that VRE strains were also more sensitive to aPDI with Zn-Phe-N 5 + . The minimum inhibitory concentrations of Van-Zn -m Phe-N 5 + were higher than those of Van alone, showing that the antibiotic properties of the Van moiety were lessened in the conjugate. In conclusion, Zn-Phe-N 5 + is a highly active PS against Gram-positive species and deserves further testing. Increasing the number of cationic charges increased aPDI efficacy on C. albicans and Gram-negative E. coli .

A new nanomaterial design was made by the construction of a tetralayered core-shell configuration, containing a magnetic core of nanospherical gamma-FeOx particle (NP) encapsulated by one plasmonic gold subshell, one middle layer of electron -polarizable C-60(>DPAF-C-n)(x)-derived fullerosome membrane, and an outer shell of organic electron donors. This class of multilayered core shell nanospherical materials was recently reported to be excellent microwave absorbers. We found that this analogous of multilayered NPs was capable of inducing photoswitchable dielectric property (permittivity) amplification at the microwave frequency range of 1.0-4.0 GHz. The enhanced phenomena were further investigated by the use of six variable organic molecular electron donors and two conducting conjugated polymers, serving as the supply of photoinduced transferrable electrons at the outer shell layer, for comparison. The design largely increased the number of polarizable charges, leading to a maximum of 387% amplification of the relative dielectric constant (epsilon(r)') value or a 159% additional increase from that of the parent trilayered precursor NPs without organic donors. The latter percentage increase of Er was contributed from the application of electron-donating hexamethylenetetraselenafulvalene molecules. Good recyclability of relative complex dielectric properties (epsilon(r)' and the derivative epsilon(r)'') back to their original values during each photoactivation cycle of light-on and light-off manipulations may allow the potential nanomaterial uses as photoswitchable dielectrics in the modulation of microwave reflection signals.

We report a novel class of highly water-soluble decacationic methano[60]fullerene decaiodides C60[>M(C3N6+C3)2]-(I−)10 [1-(I−)10] capable of co-producing singlet oxygen (Type-II) and highly reactive hydroxyl radicals, formed from superoxide radicals in Type-I photosensitizing reactions, upon illumination at both UVA and white light wavelengths. The O2‒·-production efficiency of 1-(I−)10 was confirmed by using a O2‒·-reactive bis(2,4-dinitrobenzenesulfonyl)tetrafluorofluorescein probe and correlated to the photoinduced electron-transfer event going from iodide anions to 3C60*[>M(C3N6+C3)2] leading to C60‒·[>M(C3N6+C3)2]. Incorporation of a defined number (ten) of quaternary ammonium cationic charges per C60 in 1 was aimed to enhance its ability to target pathogenic Gram-positive and Gram-negative bacterial cells. We used the well-characterized malonato[60]fullerene diester monoadduct C60[>M(t-Bu)2] as the starting fullerene derivative to provide a better synthetic route to C60[>M(C3N6+C3)2] via transesterification reaction under trifluoroacetic acid catalyzed conditions. These compounds may be used as effective photosensitizers and nano-PDT drugs for photoinactivation of pathogens.

Novel 3D-configurated stereoisomers cis-cup-tris[C60>(DPAF-C9)] and trans-chair-tris[C60>(DPAF-C9)] were designed and synthesized in good yields. The former, with three C60> cages per molecule facing at the same side of the geometrical molecular cup-shape, was proposed to provide excellent binding interaction forces at the gold surface of core-shell γ-FeOx@AuNP nanoparticles and to direct the subsequent formation of a fullerene cage array (defined as fullerosome). Upon photoactivation of the Au-layer and cis-cup-tris[C60>(DPAF-C9)] itself, the degree of photoinduced intramolecular e−-transfer from DPAF to a C60> moiety was found to be largely enhanced by the accumulated plasmonic resonance energy at the near-field surface. Distribution of resulting negative charges along the outer (C60>)-derived fullerosome shell layer of the trilayered NPs was correlated with the detected photoswitchable dielectric amplification phenomena using white LED light at 1.0 GHz.

Highly fluorescent trans- and cis-tris(fluorenylphenylamino)benzene stereo-isomeric derivatives, trans- and cis-tris(DPAF-C9), respectively, were designed and synthesized to minimize facile planar fluorene ring stacking in the solid state during thin-film device fabrications. Resulting tris-cup cis- and tris-chair trans-conformers were hypothesized to be capable of reducing direct packing contact of light-harvesting fluorene moieties from each other that should reduce the aggregation-related self-quenching effect derived from the π–π stacking packing arrangement. By the fact of closely matching photophysical characteristics of them to those of poly(N-vinylcarbazole) (PVK), we applied the former conformer as the secondary blue hole-transporting material in the study of its electroluminescence properties, using a tricomponent system of PVK‒cis-tris(DPAF-C9)‒tris(2-phenylpyridine)iridium (III) [Ir(ppy)3], as an example. Accordingly, several prototype single-layered or multilayered devices were fabricated with their electroluminescence and external quantum efficiency demonstrated. These analogous 3D-stereoconformers can also be used in other fluorescence-related thin-film applications.

We are particularly interested in mediating broad-spectrum killing of pathogenic Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria targets. Systematic evaluation was taken to evaluate a structure–function relationship of fullerene-(light harvesting antenna) conjugative diads and triads on the influence of their biological activity, aiming to achieve the optimized photodynamic inactivation (PDI) efficiency against multiantibiotics-resistant bacteria. Accordingly, we found a rational design of effective fullerene-based nano-photosensitizers by chemical modification of the carbon cage with two cell-targeting moieties each with a well-defined high number of cationic charges that allowed us to demonstrate the feasibility of these compounds giving cytotoxicity toward both Gram-positive and Gram-negative species. We also uncovered the large enhancement of PDI efficiency in photokilling of infectious bacteria by replacing the C60 cage with a C70 leading to novel type-I eicosacationic [70]fullerenes as potential nano-PDI agents.

We fabricated highly magnetic γ -FeO x @AuNP core-shell nanoparticles with deposition of fullerosome array of C 60 (>DPAF-C 9 ) at the outer shell. It formed a configuration of three-layered core-shell ( γ -FeO x @AuNP)@[C 60 (>DPAF-C 9 )] n 1 . These surface-stabilized soluble NPs were found to be capable of photoinducing surface plasmonic resonance (SPR) effect in the inner Au layer by white LED light and subsequently transfer the accumulated PR energy at the interface to the outer, partially bilayered 1 -derived fullerosome membrane layer in a near-field (~1.5 nm). The phenomena led to large amplification of dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like ( i.e . electric polarization) behavior at the frequency range of 0.5‒4.0 GHz. The effect may be suitable for designing photoresponsive dielectric-switchable nanomaterial toward applications of GHz frequency devices.

We applied a novel molecular wrapping approach to fullerenyl hybrid triads to minimize solid aggregation in coating thin-film applications. Several C60-(antenna)x and C70-(antenna)x analogous compounds having branched hybrid triads C60(>DPAF-C18)(>CPAF-C2M) and C70(>DPAF-C2)(>CPAF-C2M) nanostructures, for example, were applied in the study. The structural design was intended to facilitate the ultrafast fs intramolecular energy-transfer from photoexcited antenna to the C60> cage moiety upon two-photon pumping at either 780 or 980 nm, respectively, for broadband nonlinear optical applications. 2PA characteristics at multiple NIR wavelengths provided support for their suitability in uses that includes the 2PA ability of two antenna, DPAF (700‒850 nm) and CPAF (850‒1100 nm), and the fullerene cage at shorter wavelengths (600‒700 nm). The phenomena can be enhanced by the helical polymer wrapping technique.

Three C-60-DPAF conjugates were synthesized with one as a linear monoadduct and two as branched or starburst multiadducts in structure for the investigation of chromophore antenna number-dependent tunability of RF-responses GHz. The effect was photoinduced by the generation of surface plasmonic resonance (SPR) at the surface of trilayered nanoparticles (NPs) consisting of a highly magnetic gamma-FeO-(x)@AuNP core and an e(-)-polarizable C-60-DPAF adduct-derived partially bilayered fullerosome outer shell. Observed large dielectric (permittivity) amplification phenomena, with the maximization on the starburst multiadduct-derived nanoparticles, were correlated to the photoactivation efficiency at the gold nanolayer. We hypothesized that the prolong accumulation (or trapping) of photogenerated SPR energy in the intermediate gold layer, sandwiched between the C-60(>DPAF-C-9)(x)-derived fullerosome membrane and the highly magnetic gamma-FeOx NP core, was effectively released at the light-off stage to induce the intramolecular polarization of C-60-DPAF adducts. Resulting charged transient states were regarded as the origin of observed high permittivity-photoswitching effect. Similar tunability capabilities in subsequent measurements of distant monostatic and angle-dependent bistatic reflective SAR images might provide insights to RF-signal modulation in coating applications and the potential use of these nanomaterials as permittivity-photoswitching agents in RF-frequency devices.

We synthesized four C60-(light-harvesting antenna) dyads C60 (>CPAF-Cn) (n = 4, 9, 12, or 18) 1-Cn for the investigation of their broadband nonlinear absorption effect. Since we have previously demonstrated their high function as two-photon absorption (2PA) materials at 1000 nm, a different 2PA wavelength of 780 nm was applied in the study. The combined data taken at two different wavelength ranges substantiated the broadband characteristics of 1-Cn. We proposed that the observed broadband absorptions may be attributed by a partial π-conjugation between the C60 > cage and CPAF-Cn moieties, via endinitrile tautomeric resonance, giving a resonance state with enhanced molecular conjugation. This transient state could increase its 2PA and excited-state absorption at 800 nm. In addition, a trend of concentration-dependent 2PA cross-section (σ2 ) and excited-state absorption magnitude was detected showing a higher σ value at a lower concentration that was correlated to increasing molecular separation with less aggregation for dyads C60(>CPAF-C18) and C60(>CPAF-C9), as better 2PA and excited-state absorbers.

We unexpectedly observed a large amplification of the dielectric properties associated with the photoswitching effect and the new unusual phenomenon of delayed photoinduced capacitor-like (i.e. electric polarization) behavior at the interface on samples of three-layered core-shell (γ-FeOx@AuNP)@[C60(>DPAF-C9)](n)2 nanoparticles (NPs) in frequencies of 0.5-4.0 GHz. The detected relative dielectric constant amplification was initiated upon switching off the light followed by relaxation to give an excellent recyclability. These NPs having e(-)-polarizable fullerosomic structures located at the outer layer were fabricated from highly magnetic core-shell γ-FeOx@AuNPs. Surface-stabilized 2 in a core-shell structure was found to be capable of photoinducing the surface plasmonic resonance (SPR) effect by white LED light. The accumulated SPR energy was subsequently transferred to the partially bilayered C60(>DPAF-C9) fullerosomic membrane layer in a near-field (∼1.5 nm) region without producing radiation heat. Since the monostatic SAR signal is dielectric property-dependent, we used these measurements to provide evidence of derived reflectivity changes on a surface coated with 2 at 0.5-4.0 GHz upon illumination of LED white light. We found that a high, >99%, efficiency of response amplification in image amplitude can be achieved.

Photodynamic therapy (PDT) employs the combination of nontoxic photosensitizers (PS) and visible light that, after light absorption, can produce long-lived excited triplet states of the chromophore, that are able to carry out a sequence of photochemical reactions in the presence of oxygen to produce reactive oxygen species (ROS). These photoinduced ROS are capable of nonspecific killing of undesirable species that include cancer cells, pathogenic bacteria, fungi, and viruses. Functionalized fullerene derivatives with the preservation of an extended π-conjugation on the surface of carbon cage structure are prone to undergo photoexcitation by UV/visible light that leads to the formation of long-lived triplet states in a high quantum yield. This can facilitate photochemistry that results in the production of either reactive free radicals (Type I) or singlet oxygen (Type II) that both cause biological damage. Despite the demonstrated ability of these fullerenes to scavenge ROS as a concurrent competitive event with their production, illuminated fullerenes were found to be highly efficient in mediating PDT. Many reports have shown light-dependent in vitro killing of various cell types after incubation with functionalized fullerenes that have been chemically modified and derivatized (frequently with cationic charges) or encapsulated in drug delivery vehicles to enhance water solubility. In vivo reports of PDT with fullerenes include their use to destroy or inhibit tumors growing in mice and to increase survival in a challenging disseminated abdominal cancer model. An illuminated cationic fullerene was demonstrated to save the life of mice with wounds infected with pathogenic gram-negative bacteria. We and others have also used cationic fullerene PDT to treat mouse models of various cancers including a disseminated model of metastatic cancer in the peritoneal cavity. Multifunctional water-soluble fullerenes may have the potential to join the range of PSs that are clinically approved for use in the PDT field in the future. Accordingly, in vivo PDT with highly charged fullerene derivatives may represent a new application for disease treatment in the field of nanomedicine.

Background: Antimicrobial photodynamic inactivation with fullerenes bearing cationic charges may overcome resistant microbes. Methods & results: We synthesized C60-fullerene (LC16) bearing decaquaternary chain and deca-tertiary-amino groups that facilitates electron-transfer reactions via the photoexcited fullerene. Addition of the harmless salt, potassium iodide (10 mM) potentiated the ultraviolet A (UVA) or white light-mediated killing of Gram-negative bacteria Acinetobacter baumannii, Gram-positive methicillin-resistant Staphylococcus aureus and fungal yeast Candida albicans by 1–2+ logs. Mouse model infected with bioluminescent Acinetobacter baumannii gave increased loss of bioluminescence when iodide (10 mM) was combined with LC16 and UVA/white light. Conclusion: The mechanism may involve photoinduced electron reduction of 1(C60>)* or 3(C60>)* by iodide producing I· or I2 followed by subsequent intermolecular electron-transfer events of (C60>)–· to produce reactive radicals.