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Photodynamic therapy (PDT) is a promising non-invasive treatment modality for cancer and can be potentiated by combination with chemotherapy. Here, we combined PDT of novel porphyrin-based photosensitizers with low dose doxorubicin (Dox) to get maximum outcome. Dox potentiated and showed synergism with PDT under in vitro conditions on CT26.WT cells. The current colon cancer treatment strategies assure partial or even complete tumour regression but loco-regional relapse or distant metastasis is the major cause of death despite combination therapy. The spared cells after the treatment contribute to relapse and it is important to study their behaviour in host environment. Hence, we developed relapse models for PDT, Dox and combination treatments by transplanting respectively treated equal number of live cells to mice (n = 5) for tumour formation. Most of the treated cells lost tumour forming ability, but some treatment resistant cells developed tumours in few mice. These tumours served as relapse models and Western blot analysis of tumour samples provided clinically relevant information to delineate resistance strategies of individual as well as combination therapies at molecular level. Our results showed that low dose Dox helped in increasing the tumour inhibiting effect of PDT in combination therapy, but still there are indeed possibilities of relapse at later stages due to chemoresistance and immune suppression that may occur post-treatment. We observed that the combination therapy may also lead to the development of multidrug resistant (MDR) phenotype during relapse. Thus, this study provided clinically relevant information to further strengthen and improve PDT-drug combination therapy in order to avoid relapse and to treat cancer more effectively.

In early studies on organic solar cells with high conductivity PEDOT:PSS, the contact between ITO and PEDOT:PSS was considered ohmic. However, because low-conductivity PEDOT:PSS (such as AI4083) is mainly utilized in contemporary solar cells, the contact between ITO and PEDOT:PSS is not ohmic anymore. Despite the high possibility that there are serious interface problems, little attention has been paid to the interface between PEDOT:PSS and ITO. Most of the previous studies of interfaces in organic solar cells have focused on the interface between the active and charge transport layers. In this work, we have employed a conjugated polyelectrolyte that uses potassium poly[9,9-bis(3′-sulfonatopropyl)fluorene-alt-(9-(2,7-diethylheptyl)-carboazole)] (WPFSCz-) between ITO and low-conductivity PEDOT:PSS to overcome complicated organic–inorganic interfacial problems. The insertion of the WPFSCz- layer provides substantial advantages in the operation of polymer solar cells. First, the inserted WPFSCz- layer modifies the work-function of ITO, thereby forming an effective cascading energy alignment, which is favorable for good hole transport. Second, the introduction of the WPFSCz- layer eliminates interfacial trap sites. The reduction in traps reduces recombination losses at the interface, resulting in an improvement in the fill factor. These effects result in a significant increase in the efficiency of non-fullerene solar cells based on PM6 and Y6, from 15.86 to 17.34%. In addition, we have found that the problem of the interface in contact with ITO occurs not only in PEDOT:PSS, but also in oxide-based charge transport layers. We have confirmed that the insertion of the WPFSCz- layer between ITO and an MoO3 (or ZnO) charge transport layer shows the same positive results.

While hole extraction is crucial for the external quantum efficiency of conventional n-i-p colloidal quantum dot (CQD) solar cells (CQDSCs), sulfur-passivated p-type CQDs (pCQDs) have been the best...

Stimuli responsive π-conjugated macrocyclic systems has shown significant attention in organic electronics, however, amongst them, porphyrins and phthalocyanines unveiled remarkable growth towards materials and biological applications. Herein, we report bulk electrolysis of Zn-phthalocyanine system (ZnPc-OMe) under potential difference of 1.5 V in chloroform results anion binding mechanism directs the formation of self-assembled nanospheres by diffusion controlled approach. Electrochemical and UV–Vis absorption studies of ZnPc-OMe suggest that anion (Cl−) binding ability towards ‘Zn‘ whilst applied potential leads to the formation of H+[(Cl)ZnPc-OMe]- promote the enhanced current and charge generation. Microscopic analysis revealed that ZnPc-OMe and H+[(Cl)ZnPc-OMe]- exhibit the nanosheets and spheres with an average diameter of 0.5–1 μm and 300–500 nm, respectively. Powder X-ray diffraction analysis and raman spectra revealed the changes in crystalline phase transitions via ion-dipole and π-π stacking interactions. Thus, these unique features are atypical for phthalocyanine derivative hitherto unknown.

In this paper, we present results from the detailed investigations on the synthesis, optical, emission, electrochemical, and ultrafast nonlinear optical (NLO) properties along with the excited stat...

Although the power conversion efficiency (PCE) of inorganic perovskite-based solar cells (PSCs) has been considerably less than that of organic-inorganic hybrid PSCs due to their wider bandgap, inorganic perovskites are great candidates for the front cell in tandem devices. Herein, we demonstrate the great potential of low-temperature solution-processed two-terminal hybrid tandem solar cell devices based on spectrally matched inorganic perovskite and organic bulk heterojunction for the front and back cells, respectively. By matching optical properties of front and back cells in the hybrid tandem device by using CsPbI2Br and PTB7-Th:IEICO-4F BHJ as the active materials, we achieved a remarkably enhanced PCE in the hybrid tandem (18.04%) as compared to that of the single-junction device (12.46% for CsPbI2Br and 11.02% for PTB7- Th:IEICO-4F). Notably, the PCE of our hybrid tandem device is thus far the highest PCE among the reported tandem devices based on perovskite and organic material. Moreover, the long-term stability of inorganic perovskite devices under stress of humidity was improved in the hybrid tandem device due to the hydrophobicity of the PTB7-Th:IEICO-4F back cell. In addition, the potential promise of this type of hybrid tandem device was calculated, where a PCE of as much as 2 ~28% is possible by improving the external quantum efficiency and reducing energy loss in the sub-cells.

Ultrafast excited state molecular relaxation process in a ethynylthiophene functionalized D--A porphyrin (LG5) molecule sensitizer in solution and thin film form has been studied using femtosecond transient absorption techniques upon pumping with 400 nm.

Porphyrins are well-known anticancer agents because of their high binding affinity for G-quadruplex DNA and excellent photophysical properties. Several studies carried out using TMPyP4 established it as an efficient chemotherapeutic and a photodynamic therapeutic (PDT) agent, but its use as a lead molecule has been restricted because of its high level of binding to double-stranded DNA (dsDNA), which may have side effects on normal cells and tissues. To minimize its interaction with dsDNA and to enhance internalization into cells, an analogue of TMPyP4 (5Me) was synthesized. Its selectivity for G-quadruplex DNA over dsDNA was evaluated by spectroscopic methods, and its role in stabilizing G-quadruplex DNA was assessed by fluorescence lifetime and thermal melting experiments. Biophysical studies indicated that 5Me interacts well with G-quadruplex DNA. In vitro cytotoxicity experiments with tumor cell lines (PANC-1, B16F10, and MDA MB 231) have revealed that 5Me can inhibit the growth of cancer cells comparable to TMPyP4. MTT and apoptotic assays demonstrated the ability of 5Me to specifically affect cancer cells over normal cells. Cell cycle analysis showed that 5Me, like TMPyP4, induces G2/M phase cell cycle arrest. In addition, 5Me is more effectively taken up by both cancer and normal cells than TMPyP4. In addition, we have noticed that 5Me is more efficient than TMPyP4 in inhibiting the growth of the cancer cells after irradiation with light (600-720 nm, 20 J/cm

Origin of mixed valence states from π-conjugated photoresponsive systems offers self-assembled nanostructures facilitating excellent optoelectronic properties. Despite various electron-rich moieties, tethered linear π-conjugated systems generate charged ions however limited to standard redox-active materials until now, which further extended to macrocyclic systems. Herein, we report three carbazole and triphenylamine-assisted phthalocyanine derivatives (1, 2, and 3) and discussed the nature of photobleaching/photoionization by illumination with an excitation wavelength of 350 nm. Detailed UV–visible absorption and cyclic voltammetry studies revealed that three derivatives are bleached during irradiation; however, 3 exhibits mixed valence species in CHCl3 when compared to 1 and 2. Microscopic analysis suggested that ionized 3 forms nanospheres with an average diameter of 100–400 nm upon methanol vapor diffusion approach. Thus, photoresponsive mixed valence systems facilitated well-defined nanostructures, t...

Due to their fabulous performance, porphyrins are considered to be emerging materials for dye-sensitized solar cell applications (DSSCs). Herein, we have designed and synthesised four novel porphyrin sensitizers tethered with a triphenylimidazole group as the donor, a porphyrin macrocycle as the π-spacer and 4-ethynyl phenyl (LG15), 5-ethynylthiophene (LG16), 2,1,3-benzothiadiazole (BTD)-phenyl (LG17), and BTD-thiophene (LG18) as auxiliary acceptors and either a carboxylic acid or cyanoacrylic acid anchoring group, which resembles the structure of a donor–π-bridge–acceptor (D–π–A). The absorption spectra of LG17 and LG18 are red-shifted, when compared to LG15 and LG16, due to the presence of extended π-conjugation of the BDT group in its molecular structure. The red-shifted absorption spectra of LG17 and LG18 result in highest efficiency of 10.11% and 10.51%, respectively. Optical and electrochemical properties, and Density Functional Theory calculations of LG15–LG18, suggested that LG18 exhibits strong absorption and optimized lowest unoccupied molecular orbital (LUMO) aids the injection of electrons very effectively from the excited state of the dye into the TiO2 conduction band. Both LG17 and LG18 exhibit broad incident to photon conversion efficiency (IPCE) and the onset extends up to 950 nm, with >80% at 700 nm. Current density–voltage (J–V) curves of LG15–LG18 revealed that LG17 and LG18 exhibit highest short-circuit current density of 20.64 and 21.43 mA cm−2 resulting in power conversion efficiency (PCE) of 10.11% and 10.51%, respectively, in a liquid I−/I3− redox couple electrolyte. Bulky donor groups, π-spacer length and anchoring groups have significantly contributed to achieving high efficiency in a liquid redox shuttle that can be helpful to make efficient DSSCs for future generations. We have adopted intensity modulated photovoltage spectroscopy and nanosecond laser flash photolysis spectroscopy to explain the PCE and molecular structure relationship of the LG15–LG18 sensitizers.

In this study, a novel visible-light-driven photocatalyst was designed based on unsymmetrical zinc–phthalocyanine photosensitizer on hierarchical porous TiO2 (HPT) semiconductor. The HPT material has been prepared by a simple self-formation route. The present work successfully uses zinc phthalocyanine with spectral response extended to 700 nm triggers light harvesting center and HPT semiconductors for high photocatalytic H2 production. This novel unsymmetrical zinc–phthalocyanine (PCH001) containing three tert-butyl and two carboxylic acid groups that act as “push” and “pull” electron transfer properties from the excited dye to the TiO2 conduction band. The carboxylic group in the sensitizer serves as an anchoring group on to the surface of TiO2 and to provide intimate electronic coupling between its excited-state wave function and the conduction-band manifold of the semiconductor. The excellent photophysical properties was governed further by choosing three tert-butyl groups which tuned the LUMO level of...