A panchromatic supramolecular fullerene-based donor-acceptor assembly derived from a peripherally substituted bodipy-zinc phthalocyanine dyad.

A panchromatic 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene-zinc phthalocyanine conjugate (Bodipy-ZnPc) 1 was synthesized starting from phthalocyanine aldehyde 4, via dipyrromethane 3 and dipyrromethene 2. Conjugate 1 represents the first example in which a Bodipy unit is tethered to the peripheral position of a phthalocyanine core. Electrochemical and optical measurements provided evidence for strong electronic interactions between the Bodipy and ZnPc constituents in the ground state of 1. When conjugate 1 is subjected to photoexcitation in the spectral region corresponding to the Bodipy absorption, the strong fluorescence characteristic of the latter subunit is effectively quenched (i.e., > or = 97%). Excitation spectral analysis confirmed that the photoexcited Bodipy and the tethered ZnPc subunits interact and that intraconjugate singlet energy transfer occurs with an efficiency of ca. 25%. Treatment of conjugate 1 with N-pyridylfulleropyrrolidine (8), an electron-acceptor system containing a nitrogen ligand, gives rise to the novel electron donor-acceptor hybrid 1<-->8 through ligation to the ZnPc center. Irradiation of the resulting supramolecular ensemble within the visible range leads to a charge-separated Bodipy-ZnPc(*+)-C(60)(*-) radical-ion-pair state, through a sequence of excited-state and charge transfers, characterized by a remarkably long lifetime of 39.9 ns in toluene.

Synthesis and photophysical properties of a hydrogen-bonded phthalocyanine-perylenediimide assembly.

A supramolecular phthalocyanine-perylenediimide donor-acceptor array has been assembled by using a melamine/perylenediimide motif. Photoexcitation of the perylenediimide component affords transduction of singlet excited state energy to the energetically lower lying phthalocyanine.

A squaraine-phthalocyanine ensemble: towards molecular panchromatic sensitizers in solar cells.

A supramolecular phthalocyanine-squaraine ensemble which exhibits a large coverage of the solar spectrum from 850 to 250 nm has been prepared and characterized both photophysically and in bulk heterojunction solar cells.

A bisfullerene-bis(dipyrrinato)zinc complex: electronic coupling and charge separation in an easy-to-assemble synthetic system.

Getting connected: The use of a bis(dipyrrinato)zinc(II)) linker allows the facile tethering of two C(60) subunits and gives rise to an electronically coupled system that allows effective charge separation following photoexcitation (see figure).

Concepts for critical organ dosimetry in three-dimensional image-based breast brachytherapy.

PURPOSE: To investigate dose-volume histogram (DVH) parameters for organs at risk (OARs) in sectional three-dimensional image-based accelerated partial breast irradiation. METHODS AND MATERIALS: Skin, lung, and ribs were defined as OARs and the heart was discussed. Two different skin-contouring methods were tested on phantom before applying to the patient cohort. First, an inside skin wall contour was delineated with three different wall thicknesses to demonstrate the influence of contouring on DVH parameter. Second a structure was defined, delineated outside of the phantom surface, such that a three-dimensional skin volume was extended like a virtual bolus contour. Point dose values and DVH parameters were reported for 25 patient cases. RESULTS: The DVH parameters D0.1 cc = 65+/-21, D1 cc = 45+/-8, and D10 cc = 30+/-4 cGy/pulse for the outside skin structure around the breast corresponded to skin surface areas of 1+/-1, 6+/-3, and 6+/-11cm2. Lung volume receiving 20 Gyalphabeta3 was 8.3+/-11cm3. D0.1 cc and D2 cc in the most exposed rib were 0.7+/-0.3 and 0.4+/-0.2 Gy/pulse, respectively. CONCLUSION: In accelerated partial breast irradiation treatment planning, dose to OAR can be reported in a more sophisticated way with DVH parameters than using points only. The suggested method of skin delineation using the defined outside structure allows calculating reliable and reproducible DVH parameters.

Electron transfer in Me-blocked heterodimeric alpha,gamma-peptide nanotubular donor-acceptor hybrids.

Bio-inspired cyclopeptidic heterodimers built on beta-sheet-like hydrogen-bonding networks and bearing photoactive and electroactive chromophores on the outer surface have been prepared. Different cross-strand pairwise relationships between the side chains of the cyclic alpha,gamma-peptides afford the heterodimers as three nonequivalent dimeric species. Steady-state and time-resolved spectroscopies clearly show an electron transfer process from pi-extended tetrathiafulvalene, covalently attached to one of the cyclopeptides, to photoexcited [60]fullerene, located on the complementary cyclopeptide. The charge-separated state was stabilized for up to 1 micros before recombining and repopulating the ground state. Our current example shows that cyclopeptidic templates can be successfully used to form light-harvesting/light-converting hybrid ensembles with a distinctive organization of donor and acceptor units able to act as efficient artificial photosystems.

Photophysical characterization of a cytidine-guanosine tethered phthalocyanine-fullerene dyad.

A new non-covalent electron transfer model system, based on the use of cytidine-guanosine hydrogen bonding interactions, is described that incorporates a phthalocyanine photodonor and a C60 fullerene acceptor.

Broadly tunable dual-wavelength light source for coherent anti-Stokes Raman scattering microscopy.

The signal and idler beams from a picosecond, synchronously pumped optical parametric oscillator (OPO) provide the two colors necessary for coherent anti-Stokes Raman scattering (CARS) microscopy. The OPO provides a continuously tunable frequency difference between the two beams over a broad range of Raman shifts (100-3700 cm(-1)) by varying the temperature of a single nonlinear crystal. The near-infrared output (900-1300 nm) allows for deep penetration into thick samples and reduced nonlinear photodamage. Applications of this light source to in vivo cell and ex vivo tissue imaging are demonstrated.

Continuum generation in a novel photonic crystal fiber for ultrahigh resolution optical coherence tomography at 800 nm and 1300 nm.

Ultrahigh resolution optical coherence tomography (OCT) is demonstrated at 800 nm and 1300 nm using continuum generation in a single photonic crystal fiber with a parabolic dispersion profile and two closely spaced zero dispersion wavelengths. Both wavelengths are generated simultaneously by pumping the fiber with ~78 mW average power at 1064 nm in a 52 MHz, 85 fs pulse train from a compact Nd:Glass oscillator. Continuum processes result in a double peak spectrum with > 110 nm and 30 mW average power at 800 nm and > 150 nm and 48 mW at 1300 nm. OCT imaging with < 5 mum resolution in tissue at 1300 nm and < 3 mum resolution at 800 nm is demonstrated. Numerical modeling of propagation was used to predict the spectrum and can be used for further optimization to generate smooth, broad spectra for OCT applications.

Quasi-synchronous pumping of modelocked few-cycle Titanium Sapphire lasers.

We investigate the modelocking dynamics of quasi-synchronously pumped, dispersion managed Kerr-lens modelocked Titanium-Sapphire lasers. For the first time, self-starting few-cycle laser pulses with 6 fs pulse duration and ultrabroadband optical spectra are demonstrated without using any intracavity elements like saturable absorbers.

Locally recurrent breast cancer: pulse dose rate brachytherapy for repeat irradiation following lumpectomy-- a second chance to preserve the breast.

PURPOSE: To perform and assess the effectiveness of local excision of recurrent tumor followed by postoperative pulse dose rate (PDR) brachytherapy. MATERIALS AND METHODS: From 1994 to 2000, 17 patients who had small recurrent breast carcinomas after initially undergoing breast-conserving therapy (BCT), which included postoperative radiation therapy, were treated with local tumor excision and PDR brachytherapy. Recurrences occurred at a median time of 50 months (range, 11-208 months) after primary treatment. Eight patients underwent a combination of PDR brachytherapy (total dose range, 12.5-28.0 Gy) and external-beam radiation therapy (EBT) (total dose range, 12-30 Gy). Nine patients underwent radiation therapy with 40.2-50.0-Gy PDR brachytherapy only. The prescribed radiation dose was 0.5-1.0 Gy per pulse. Patients were examined for local tumor control and treatment-related side effects. RESULTS: Twelve of 17 patients had no local tumor at a median follow-up time of 59 months (range, 20-84 months); two of these patients showed signs of having distant disease. One patient died after a cerebral stroke without evidence of tumor. Four women treated with combined EBT and brachytherapy had secondary local tumor recurrences 4, 8, 8, and 11 months after therapy and had to undergo mastectomy. Despite having undergone radiation therapy previously, patients had side effects limited to moderate (grade 1-2) fibrosis. CONCLUSION: Local tumor excision combined with PDR brachytherapy for small local-regional tumor recurrences after primary BCT is feasible and well tolerated and might obviate mastectomy. Preliminary experiences are encouraging. Further studies are required for appropriate patient selection.

Long-term results (10 years) of intensive breast conserving therapy including a high-dose and large-volume interstitial brachytherapy boost (LDR/HDR) for T1/T2 breast cancer.

BACKGROUND AND PURPOSE: During the past 15 years many retrospective studies and prospective randomized trials have been published supporting the use of breast conserving treatment (BCT) including surgery and radiotherapy. However, there are still many controversies on the necessary amount of resection, the width of the resection margins and the optimal radiation technique, dose and volume, in particular of the boost. In this retrospective study a large cohort of 410 women with early breast cancer treated with BCT including an interstitial brachytherapy (BT) boost is evaluated after a long follow-up period. MATERIAL AND METHODS: In order to clarify the impact of the different treatment-related factors on local control, these were carefully discriminated, based on widely accepted classification and reporting systems for surgery as well as for radiotherapy. The surgical approach was classified according to EORTC criteria and a high rate of quadrantectomies (60%) was found. Dose and volume of interstitial BT is reported according to recommendations of ICRU 58, and reveals a significant radiation dose and volume: minimum target dose, mean central dose (MCD) and '85% of MCD' for low-dose rate (LDR) BT was mean 20, 28 and 24 Gy, for high-dose rate (HDR) BT it was mean '10, 15 and 13 Gy, respectively; the treated volume was 104 cc for LDR BT and 83 cc for HDR BT. RESULTS: The actuarial rates for overall survival, disease-free survival and disease-specific survival were 97, 90 and 98% at 5 years and 85, 79 and 92% at 10 years. There have been only 16 breast recurrences in 410 treated patients resulting in a 5- and 10-year actuarial local recurrence rate of 2 and 3.9%, respectively; six recurrences (1.5%) were in the original quadrant. Except age and menopausal status, all tumour- and patient-related risk factors had no significant impact on local control. CONCLUSIONS: Our data confirm that intensive BCT leads to excellent long-term results in terms of local control, masking classical risk factors. This high-dose and large-volume interstitial BT seems to be superior to classical BCT without BT.