Diplatinum(II) Catecholate of Photoactive Boron-Dipyrromethene for Lysosome-Targeted Photodynamic Therapy in Red Light.

The binuclear platinum(II) boron-dipyrromethene (BODIPY) complex [{Pt(dach)}2(µ-Dcrb)] (DP), where dach is 1,2-diaminocyclohexane and H4Dcrb is a morpholine-conjugated BODIPY-linked dicatechol bridging ligand, was prepared for lysosome organelle targeting and near-IR (NIR) light (600-720 nm) induced photocytotoxic activity. The platinum complex [Pt(dach)(cat)] (CP), where H2cat is catechol, was synthesized and used as a control complex without bearing the BODIPY unit. The complex DP displayed a band at 660 nm (ε = 2.1 × 104 M-1 cm-1) in the red region of the UV-visible spectrum recorded in 10% dimethyl sulfoxide/Dulbecco's Modified Eagle's Medium (DMSO/DMEM, pH 7.2). The complex DP and the BODIPY ligand displayed emission in 10% DMSO-DMEM (pH 7.2) giving an λem value of 668 nm (λex = 650 nm) with a ΦF value of 0.02 for DP and 0.16 for H4Dcrb (ΦF, fluorescence quantum yield). Titration experiments using 1,3-diphenylisobenzofuran (DPBF) indicated that the complex DP and H4Dcrb on irradiation with near-IR light of 600-720 nm generated singlet oxygen (1O2) as the ROS (reactive oxygen species). The complex DP showed significant lysosomal localization and remarkable apoptotic photodynamic therapy (PDT) effects, giving half-maximal inhibitory concentration values (IC50) within 0.6-3.4 µM in HeLa cervical cancer, A549 lung cancer, and MDA-MB231 multidrug resistant cancer cells, while being essentially nontoxic in the dark and in the HPL1D immortalized lung epithelial normal cells. The acridine orange assay using A549 cells showed lysosomal membrane permeabilization by the complex DP under near-IR light (600-720 nm). This complex on near-IR light (600-720 nm) activation in A549 cells induced apoptotic cell death, as observed from an Annexin-V FITC assay.

Glucose-Appended Platinum(II)-BODIPY Conjugates for Targeted Photodynamic Therapy in Red Light.

Platinum(II) complexes [Pt(L1)(R-BODIPY)]Cl (1) and [Pt(L2)(R-BODIPY)]Cl (2), where R-BODIPY is 8-(4-ethynylphenyl)-distyryl-4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3, L1 is 4'-phenyl-2,2':6',2″-terpyridine, and L2 is (2,2':6',2″-terpyridin-4'-oxy)ethyl-ß-d-glucopyranoside, were synthesized and characterized, and their photocytotoxicity was studied. The phenylacetylide complex [Pt(L1)(C≡CPh)]Cl (3) was prepared and used as a control. Complexes 1 and 2 showed near-IR absorption bands at 713 nm (ε = 3.47 × 104 M-1 cm-1) and 715 nm (3.2 × 104 M-1 cm-1) in 10% dimethyl sulfoxide (DMSO)-Dulbecco's Modified Eagle's Medium (DMEM) (pH 7.2). The BODIPY complexes are emissive in 10% DMSO-DMEM at pH 7.2 with λem (λex, Φf) = 822 nm (710 nm, 0.022) for complex 1 and λem (λex, Φf) = 825 nm (710 nm, 0.026) for complex 2. They generated singlet oxygen (1O2) in red light as evidenced from 1,3-diphenylisobenzofuran (DPBF) titration experiments. The singlet oxygen quantum yield (ΦΔ) values for 1 and 2 were ∼0.6 signifying their photosensitizing ability. They were remarkably photodynamic therapy (PDT) active in red light showing significant red light-induced cytotoxicity in cervical HeLa, lung cancer A549, and breast cancer MCF-7 cells (IC50: 2.3-24.7 µM in light) with negligible dark toxicity (IC50 > 100 µM). A significant enhancement in cellular uptake was observed for 2 having glucose-appended terpyridine ligand compared to 1. The confocal microscopy showed significant mitochondrial localization of the complexes as evidenced from the JC-1 assay. The complexes released the photoactive R-BODIPY ligand upon red light-irradiation as evidenced from the mass and 1H NMR spectral studies. Complex 2 is remarkable in satisfying the essential requirements of targeted PDT in red light.

Pyriplatin-Boron-Dipyrromethene Conjugates for Imaging and Mitochondria-Targeted Photodynamic Therapy.

Monofunctional pyriplatin analogues cis-[Pt(NH3)2(L)Cl](NO3) (1-3) having boron-dipyrromethene (BODIPY) pendants (L) with 1,3,5,7-tetramethyl-8-(4-pyridyl)-4,4'-difluoroboradiazaindacene moieties were designed and synthesized, and their photocytotoxic properties were studied. The Pt-BODIPY conjugates displayed an absorption band within 505-550 nm and a green emissive band near 535 nm in 1% DMSO/DMEM (Dulbecco's modified Eagle's medium) buffer. Complex cis-[Pt(NH3)2(4-Me-py)Cl](NO3) (4) was used as a control for determining the structural aspects by X-ray crystallography. The mono- and diiodinated BODIPY complexes 2 and 3 showed generation of singlet oxygen on light activation as evidenced from the 1,3-diphenylisobenzofuran (DPBF) titration experiments. The cytotoxicity of the BODIPY complexes was tested against A549 (human lung cancer), MCF-7 (human breast cancer), and HaCaT (human skin keratinocyte) cells in dark and visible light (400-700 nm, 10 J cm-2). While complexes 2 and 3 showed excellent photocytotoxicity (IC50 ≈ 0.05 µM), they remained essentially nontoxic in the dark (IC50 > 100 µM). The emissive bands of 1 and 2 were used for cellular imaging by confocal microscopy study, which showed their mitochondrial localization. This was further supported by platinum estimation from isolated mitochondria and mitochondrial depolarization through a JC-1 assay. The photomediated apoptotic cell death was evidenced from flow cytometric assays, annexin-V/FITC-PI (fluorescein isothiocyanate-propidium iodide) and cell cycle arrest in sub-G1 and G2/M phases. The complexes bind to 9-ethylguanine as a model nucleobase to form monoadducts. A mechanistic study on DNA photocleavage activity using pUC19 DNA showed singlet oxygen as the reactive oxygen species (ROS). The combination of photodynamic therapy with DNA cross-linking property enhanced the anticancer potential of the monofunctional BODIPY-conjugates of pyriplatins.

Monofunctional BODIPY-Appended Imidazoplatin for Cellular Imaging and Mitochondria-Targeted Photocytotoxicity.

Monofunctional platinum(II) complexes of formulation cis-[Pt(NH3)2(L)Cl](NO3), where L is an imidazole base conjugated to 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) with emissive (L1 in 1) and nonemissive (L2 in 2) moieties were prepared and characterized, and their singlet oxygen-mediated photoinduced cytotoxicity was studied. The 1-methylimidazole (1-MeIm) complex 3 was prepared as a control and for structural characterization by X-ray crystallography. Complexes 1 and 2 showed strong visible absorption bands at 500 nm (ε = 2.7 × 104 M-1 cm-1) and 540 nm (1.4 × 104 M-1 cm-1). Complex 1 is emissive with a band at 510 nm (ΦF = 0.09) in 1% dimethyl sulfoxide/Dulbecco's Modified Eagle's Medium (pH 7.2). Singlet oxygen generation upon photoirradiation with visible light (400-700 nm) was evidenced from 1,3-diphenylisobenzofuran titration experiments showing significant photosensitizing ability of the BODIPY complexes. Both 1 and 2 were remarkably photocytotoxic in visible light (400-700 nm, 10 J cm-2) in skin keratinocyte HaCaT and breast cancer MCF-7 cells giving IC50 values in nanomolar concentration. The complexes were, however, essentially nontoxic to the cells in the dark (IC50 > 80 µM). Complex 2 having a diiodo-BODIPY unit is nonemissive but an efficient photosensitizer with high singlet oxygen generation ability in visible light (400-700 nm). Confocal microscopy using the emissive complex 1 showed significant mitochondrial localization of the complex. Cell death via apoptotic pathway was observed from the Annexin-V-FITC/PI assay. The formation of Pt-DNA adducts was evidenced from the binding experiments of the complexes 1 and 2 with 9-ethylguanine as a model nucleobase from 1H NMR and mass spectral studies.

The cis-Diammineplatinum(II) Complex of Curcumin: A Dual Action DNA Crosslinking and Photochemotherapeutic Agent.

[Pt(cur)(NH3)2](NO3) (1), a curcumin-bound cis-diammineplatinum(II) complex, nicknamed Platicur, as a novel photoactivated chemotherapeutic agent releases photoactive curcumin and an active platinum(II) species upon irradiation with visible light. The hydrolytic instability of free curcumin reduces upon binding to platinum(II). Interactions of 1 with 5'-GMP and ct-DNA indicated formation of platinum-bound DNA adducts upon exposure to visible light (λ=400-700 nm). It showed apoptotic photocytotoxicity in cancer cells (IC50 ≈ 15 µM), thus forming (⋅)OH, while remaining passive in the darkness (IC50 >200 µM). A comet assay and platinum estimation suggest Pt-DNA crosslink formation. The fluorescence microscopic images showed cytosolic localization of curcumin, thus implying possibility of dual action as a chemo- and phototherapeutic agent.

Caprolactone-Based Biodegradable Polymer for Selective, Sensitive Detection and Removal of Cu2+ Ions from Water.

Even though heavy and transition metals originated in the earth's crust, the significant human exposure and environmental pollution consequences of anthropogenic activities include industrial production and waste, mining and smelting operations, and agricultural and domestic usage of metals. Because of their nonbiodegradable nature, heavy metal ions such as Cu2+ accumulate very quickly in plants and edible animals, ultimately ending up in the human food cycle. Therefore, to nullify the detrimental effects of Cu2+ ions for the sake of the environment and living organisms, we are motivated to design a sensor molecule that can not only detect Cu2+ ions but also remove them selectively from the water medium. To detect the Cu2+ ions, we synthesized a monomer (NCu) and its biodegradable caprolactone-based polymer (PNCu). It was observed that both NCu and PNCu showed higher selectivity toward Cu2+ ions by changing the color from colorless to yellow, with a limit of detection value of 29 nM and 0.3 µM. Furthermore, removing the Cu2+ ions from the water solution was also accomplished by introducing the hydrophobicity of the polymer (PNCu) through the ring-opening polymerization process. Due to increased hydrophobicity, the polymer produced a yellow color precipitate upon adding Cu2+ ions to the solution; thus, removal of the metal ion is possible using our designed polymer and its detection ability. We checked the removal efficiency of our polymer by using UV-vis spectroscopy and EDX analysis, which indicated that almost all of the copper is removed by our polymer. Therefore, to our knowledge, this is the first biodegradable caprolactone-based polymer for colorimetric turn-on detection and separation of the Cu2+ ions from the water.

ADNet++: A few-shot learning framework for multi-class medical image volume segmentation with uncertainty-guided feature refinement.

A major barrier to applying deep segmentation models in the medical domain is their typical data-hungry nature, requiring experts to collect and label large amounts of data for training. As a reaction, prototypical few-shot segmentation (FSS) models have recently gained traction as data-efficient alternatives. Nevertheless, despite the recent progress of these models, they still have some essential shortcomings that must be addressed. In this work, we focus on three of these shortcomings: (i) the lack of uncertainty estimation, (ii) the lack of a guiding mechanism to help locate edges and encourage spatial consistency in the segmentation maps, and (iii) the models' inability to do one-step multi-class segmentation. Without modifying or requiring a specific backbone architecture, we propose a modified prototype extraction module that facilitates the computation of uncertainty maps in prototypical FSS models, and show that the resulting maps are useful indicators of the model uncertainty. To improve the segmentation around boundaries and to encourage spatial consistency, we propose a novel feature refinement module that leverages structural information in the input space to help guide the segmentation in the feature space. Furthermore, we demonstrate how uncertainty maps can be used to automatically guide this feature refinement. Finally, to avoid ambiguous voxel predictions that occur when images are segmented class-by-class, we propose a procedure to perform one-step multi-class FSS. The efficiency of our proposed methodology is evaluated on two representative datasets for abdominal organ segmentation (CHAOS dataset and BTCV dataset) and one dataset for cardiac segmentation (MS-CMRSeg dataset). The results show that our proposed methodology significantly (one-sided Wilcoxon signed rank test, p<0.05) improves the baseline, increasing the overall dice score with +5.2, +5.1, and +2.8 percentage points for the CHAOS dataset, the BTCV dataset, and the MS-CMRSeg dataset, respectively.

Anomaly detection-inspired few-shot medical image segmentation through self-supervision with supervoxels.

Recent work has shown that label-efficient few-shot learning through self-supervision can achieve promising medical image segmentation results. However, few-shot segmentation models typically rely on prototype representations of the semantic classes, resulting in a loss of local information that can degrade performance. This is particularly problematic for the typically large and highly heterogeneous background class in medical image segmentation problems. Previous works have attempted to address this issue by learning additional prototypes for each class, but since the prototypes are based on a limited number of slices, we argue that this ad-hoc solution is insufficient to capture the background properties. Motivated by this, and the observation that the foreground class (e.g., one organ) is relatively homogeneous, we propose a novel anomaly detection-inspired approach to few-shot medical image segmentation in which we refrain from modeling the background explicitly. Instead, we rely solely on a single foreground prototype to compute anomaly scores for all query pixels. The segmentation is then performed by thresholding these anomaly scores using a learned threshold. Assisted by a novel self-supervision task that exploits the 3D structure of medical images through supervoxels, our proposed anomaly detection-inspired few-shot medical image segmentation model outperforms previous state-of-the-art approaches on two representative MRI datasets for the tasks of abdominal organ segmentation and cardiac segmentation.

BODIPY-dipicolylamine complexes of platinum(II): X-ray structure, cellular imaging and organelle-specific near-IR light type-II PDT.

Dipicolylamine (dpa) based platinum(II) complexes [Pt(L1-3)Cl]Cl (1-3), where L2 and L3 are green and red light BODIPY-tagged dpa ligands and L1 is a benzyl derivative of dpa, were synthesized and characterized and their in vitro cytotoxicity was studied. The perchlorate salt of complex 2 was structurally characterized. It showed a PtN3Cl core with a deformed square-planar geometry. At pH 7.2, complexes 2 and 3 showed strong absorption bands at 500 nm (ε ∼6.8 × 104 dm3 mol-1 cm-1) and 653 nm (ε ∼1.0 × 105 dm3 mol-1 cm-1) in a 1 : 1 (v/v) mixture of dimethyl sulfoxide and Dulbecco's phosphate-buffered saline (DMSO/DPBS), respectively. They displayed respective emission bands at 515 and 677 nm having fluorescence quantum yield values of 0.36 and 0.25. Complex 3 generated singlet oxygen, as evidenced from the 1,3-diphenylisobenzofuran titration experiments and mechanistic DNA photocleavage study. It showed high photocytotoxicity in red light (600-720 nm) with half-maximal inhibitory concentration (IC50) values of 1.73 and 2.67 µM in HeLa and A549 cells. The complexes showed significantly reduced chemo-PDT activity in a non-cancerous HPL1D cell line and in the dark. The 2',7'-dichlorofluorescein diacetate assay revealed reactive oxygen species-mediated type-II photodynamic therapy (PDT) activity. Cellular imaging of A549 cancer cells using complexes 2 and 3 revealed their preferential localization in mitochondria and endoplasmic reticulum. The annexin V-FITC/PI assay confirmed apoptotic cell damage. Cell cycle analysis indicated arrest in the G1 phase upon red light irradiation. Pt-DNA adduct formation was proposed from a DNA binding experiment with green light active complex 2 and 9-ethylguanine as a nucleobase from the mass spectral study.

Red light active Pt(iv)-BODIPY prodrug as a mitochondria and endoplasmic reticulum targeted chemo-PDT agent.

A cisplatin-based platinum(iv) prodrug, [Pt(NH3)2Cl2(OH)(L 1 )], having L 1 as a red-light active boron-dipyrromethene (BODIPY) pendant, was synthesized and characterized and its application as a chemo-cum-photodynamic therapy agent was studied. Me-L 1 as the ligand precursor is structurally characterized. The complex displayed an intense absorption band near 650 nm (ε ∼ 8.8 × 104 dm3 mol-1 cm-1) in 1 : 1 (v/v) DMSO/DPBS. It showed an emission band at 674 nm (λ ex = 630 nm) with a fluorescence quantum yield (Φ F) value of 0.37. In red light (600-720 nm), it generated singlet oxygen as evidenced from the 1,3-diphenylisobenzofuran (DPBF) titration experiment giving a singlet oxygen quantum yield (Φ Δ) value of 0.28 in DMSO. The mechanistic pUC19 DNA photocleavage study and singlet oxygen sensor green (SOSG) assay ascertained its ability to generate singlet oxygen in both extracellular and intracellular media by a type-II photo-process. The complex exhibited high stability in the dark, but on red-light irradiation, it displayed rapid activation in the presence of a reducing environment. It displayed remarkable apoptotic photocytotoxicity with half-maximal inhibitory concentration (IC50) ranging from 0.58 to 0.76 µM in human cervical cancer (HeLa) and breast cancer (MCF-7) cells with a respective photo-cytotoxicity index value of >172 and >131. The photodynamic activity was significantly less in non-cancerous human peripheral lung epithelial (HPL1D) cells. The emissive complex showed localization in the mitochondria and endoplasmic reticulum (ER) with a similar Pearson's correlation coefficient value, making it a dual organelle-targeted therapeutic agent. JC-1, fluo-4-AM and annexin V-FITC/propidium iodide assays in HeLa cells showed cellular apoptosis by arresting cells in the sub-G1 phase via mitochondrial dysfunction and ER stress.

Diabetes and Its Complications: Therapies Available, Anticipated and Aspired.

Worldwide, diabetes ranks among the ten leading causes of mortality. Prevalence of diabetes is growing rapidly in low and middle income countries. It is a progressive disease leading to serious co-morbidities, which results in increased cost of treatment and over-all health system of the country. Pathophysiological alterations in Type 2 Diabetes (T2D) progressed from a simple disturbance in the functioning of the pancreas to triumvirate to ominous octet to egregious eleven to dirty dozen model. Due to complex interplay of multiple hormones in T2D, there may be multifaceted approach in its management. The 'long-term secondary complications' in uncontrolled diabetes may affect almost every organ of the body, and finally may lead to multi-organ dysfunction. Available therapies are inconsistent in maintaining long term glycemic control and their long term use may be associated with adverse effects. There is need for newer drugs, not only for glycemic control but also for prevention or mitigation of secondary microvascular and macrovascular complications. Increased knowledge of the pathophysiology of diabetes has contributed to the development of novel treatments. Several new agents like Glucagon Like Peptide - 1 (GLP-1) agonists, Dipeptidyl Peptidase IV (DPP-4) inhibitors, amylin analogues, Sodium-Glucose transport -2 (SGLT- 2) inhibitors and dual Peroxisome Proliferator-Activated Receptor (PPAR) agonists are available or will be available soon, thus extending the range of therapy for T2D, thereby preventing its long term complications. The article discusses the pathophysiology of diabetes along with its comorbidities, with a focus on existing and novel upcoming antidiabetic drugs which are under investigation. It also dives deep to deliberate upon the novel therapies that are in various stages of development. Adding new options with new mechanisms of action to the treatment armamentarium of diabetes may eventually help improve outcomes and reduce its economic burden.

Oxoplatin-B, a cisplatin-based platinum(IV) complex with photoactive BODIPY for mitochondria specific "chemo-PDT" activity.

Oxoplatin-B, a platinum(IV) complex [Pt(NH3)2Cl2(L1)(OH)] (1) of 4-methylbenzoic acid (HL1) functionalized with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) was prepared, characterized and its antitumor activity studied. [Pt(NH3)2Cl2(L2)(OH)] (2) of 4-methylbenzoic acid (HL2) was studied as a control. Complex 1 showed an absorption band at 500 nm (ɛ = 4.34 × 104 M-1 cm-1) and an emission band at 515 nm (λex = 488 nm, ΦF = 0.64) in 1% dimethyl sulfoxide/Dulbecco's Modified Eagle's Medium (pH = 7.2). Visible light-induced (400-700 nm) generation of singlet oxygen was evidenced from 1,3-diphenylisobenzofuran titration study. Complex 1 showed photo-induced cytotoxicity in visible light (400-700 nm, 10 J cm-2) against human breast cancer (MCF-7), cervical cancer (HeLa) and lung cancer (A549) cells (IC50: 1.1-3.8 µM) while being less toxic in normal cells. Confocal imaging showed mitochondrial localization with additional evidence from platinum content from isolated mitochondria and 5,5,6,6'-tetrachloro-1,1',3,3' tetraethylbenzimi-dazoylcarbocyanine iodide (JC-1) assay. Cellular apoptosis was observed from Annexin-V-FITC (fluorescein isothiocyanate)/propidium iodide assay.

Photocytotoxic cancer cell-targeting platinum(ii) complexes of glucose-appended curcumin and biotinylated 1,10-phenanthroline.

Mixed-ligand platinum(ii) complexes, [Pt(phen)(pacac)](NO3) (1), [Pt(phen)(cur)](NO3) (2), [Pt(bt-phen)(cur)](NO3) (3) and [Pt(phen)(scur)](NO3) (4), where phen is 1,10-phenanthroline, bt-phen is 5-biotin-1,10-phenanthroline, pacac is 1,3-diphenyl-1,3-propanedioate anion, Hcur is curcumin and Hscur is diglucosylcurcumin, were prepared, characterized and their anticancer activity studied. Complexes 2-4 showed absorption bands within 410-430 nm (ε, 2.1 × 104 to 2.8 × 104 M-1 cm-1) in 10% DMSO-DPBS (Dulbecco's phosphate-buffered saline) and emission bands near 530 nm (λex = 410-430 nm) with a fluorescence quantum yield (ΦF) value of ∼0.02. The curcumin complexes showed stability over a study period of 48 h. The photocytotoxicity was studied using human cervical HeLa, human liver HepG2, human breast cancer MDA-MB 231 and human lung adenocarcinoma A549 cancer cells along with human immortalized lung epithelial HPL1D as normal cells. Complexes 2-4 showed apoptotic photo-induced cell death in light of wavelength 400-700 nm (IC50, half maximal inhibitory concentration: 6-28 µM) by reactive oxygen species (ROS), while remaining inactive in the dark (IC50: 43-95 µM). The selectivity of the complexes 3 and 4 was enhanced significantly towards the cancer cells than towards the normal cells, thus making them targeted photochemotherapeutic agents. The ROS formation and mode of cell death were studied from 2',7'-dichlorofluorescein diacetate (DCFDA) and annexin-V/FITC (fluorescein isothiocyanate)-PI assays, respectively. Preferential nuclear and mitochondrial localization was evidenced from inductively coupled plasma mass spectrometry (ICP-MS) studies.

BODIPY-Appended 2-(2-Pyridyl)benzimidazole Platinum(II) Catecholates for Mitochondria-Targeted Photocytotoxicity.

Platinum(II) complexes of the type [Pt(L)(cat)] (1 and 2), in which H2 cat is catechol and L represents two 2-(2-pyridyl)benzimidazole ligands with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) pendants, were synthesized to achieve mitochondria-targeted photocytotoxicity. The complexes showed strong absorptions in the range λ=510-540 nm. Complex 1 exhibited intense emission at λ=525 nm in 1 % DMSO/water solution (fluorescence quantum yield of 0.06). Nanosecond transient absorption spectral features indicated an enhanced population of the triplet excited state in di-iodinated complex 2. The generation of singlet oxygen by complex 2 upon exposure to visible light, as evidenced from experiments with 1,3-diphenylisobenzofuran, is suitable for photodynamic therapy because of the remarkable photosensitizing ability. The complexes resulted in excellent photocytotoxicity in HaCaT cells (half maximal inhibitory concentration IC50 ≈3 µm, λ=400-700 nm, light dose=10 J cm(-2) ), but they remained non-toxic in the dark (IC50 >100 µm). Confocal microscopy images of 1 and Pt estimation from isolated mitochondria showed colocalization of the complexes in the mitochondria. Complex 2 displayed generation of reactive oxygen species induced by visible light, disruption of the mitochondrial membrane potential, and apoptosis.