Saccharide substituted zinc phthalocyanines: optical properties, interaction with bovine serum albumin and near infrared fluorescence imaging for sentinel lymph nodes

Design consideration of phthalocyanines as sensitizers for enhanced sono-photodynamic combinatorial therapy of cancer

Cancer remains one of the diseases with the highest incidence and mortality globally. Conventional treatment modalities have demonstrated threatening drawbacks including invasiveness, non-controllability, and development of resistance for some, including chemotherapy, radiation, and surgery. Sono-photodynamic combinatorial therapy (SPDT) has been developed as an alternative treatment modality which offers a non-invasive and controllable therapeutic approach. SPDT combines the mechanism of action of sonodynamic therapy (SDT), which uses ultrasound, and photodynamic therapy (PDT), which uses light, to activate a sensitizer and initiate cancer eradication. The use of phthalocyanines (Pcs) as sensitizers for SPDT is gaining interest owing to their ability to induce intracellular oxidative stress and initiate toxicity under SDT and PDT. This review discusses some of the structural prerequisites of Pcs which may influence their overall SPDT activities in cancer therapy.

Porphyrinoid-based photosensitizers for diagnostic and therapeutic applications: An update

Porphyrin-based molecules are actively studied as dual function theranostics: fluorescence-based imaging for diagnostics and fluorescence-guided therapeutic treatment of cancers. The intrinsic fluorescent and photodynamic properties of the bimodal molecules allows for these theranostic approaches. Several porphyrinoids bearing both hydrophilic and/or hydrophobic units at their periphery have been developed for the aforementioned applications, but better tumor selectivity and high efficacy to destroy tumor cells is always a key setback for their use. Another issue related to their effective clinical use is that, most of these chromophores form aggregates under physiological conditions. Nanomaterials that are known to possess incredible properties that cannot be achieved from their bulk systems can serve as carriers for these chromophores. Porphyrinoids, when conjugated with nanomaterials, can be enabled to perform as multifunctional nanomedicine devices. The integrated properties of these porphyrinoid-nanomaterial conjugated systems make them useful for selective drug delivery, theranostic capabilities, and multimodal bioimaging. This review highlights the use of porphyrins, chlorins, bacteriochlorins, phthalocyanines and naphthalocyanines as well as their multifunctional nanodevices in various biomedical theranostic platforms.

In vitro interaction and computational studies of glycosylated photosensitizers with plasma proteins

A series of glycosylated photosensitizers (porphyrin, chlorin, and isobacteriochlorin) in the presence of plasma proteins: bovine serum albumin (BSA) and human serum albumin (HSA), were investigated in a buffer at pH 7.4, using ultraviolet-visible (UV-vis) absorption and fluorescence spectroscopies. Due to the excitation of the tryptophan residue of BSA and HSA, its fluorescence emission was monitored around 340 nm. During each titration experiment and with each addition of the corresponding glycosylated photosensitizer, there was a concentration-dependent quenching of the intrinsic fluorescence of BSA and HSA. Using Stern–Volmer and double logarithmic plots we determined that fluorescence quenching was static for all molecules. We calculated the average binding constant for BSA and HSA for each porphyrin-type compound. To support our experimental studies, computational molecular docking and molecular dynamics simulations were used to identify the binding sites and binding poses of the each of the glycosylated photosensitizers onto BSA and HSA. The three compounds are binding to the Hemin site located in the subdomain IB of BSA forming strong interactions with Trp134, while they are binding to the subdomain IIA of HSA close to the Sudlow’s site I, and interacting with Trp214.

Subphthalocyanine as a fluorescence imaging agent for breast tumor

Tri-tert-butyl-carboxyl subphthalocyanine (SubPc) was synthesized and evaluated as a fluorescence agent. Fluorescence imaging for breast tumor in vivo was performed using nude mice as models. Results indicate high uptake in tumor at 20 h. Tumor-non tumor ratio was determined as 2.25. The imaging results demonstrate the potential of this fluorescence-imaging agent in the diagnosis of breast tumor. In the future, subphthalocyanine is also developing as a dual functional, which is fluorescence imaging and as a photodynamic therapeutic agent for the treatment and diagnosis of cancer.

Axially Decorated SiIV -phthalocyanines Bearing Mannose- or Ammonium-conjugated Siloxanes: Comparative Bacterial Labeling and Photodynamic Inactivation<sup/>

Herein, we present a comparative study about the photoinactivation of Staphylococcus aureus (Gram-positive model) and Escherichia coli (Gram-negative model) employing a neutral and a dicationic axially functionalized Si^IV -phthalocyanine. Depending on the charge of the siloxane moiety (neutral monosaccharide or cationic ammonium salt), different interactions with the bacteria were observed, and a differential photoinactivation was facilitated. The intensity of the fluorescence labeling correlated with the photoinactivation of the two types of bacteria: While the neutral species only significantly affected the Gram-positive cells, we observed that the positively charged photosensitizer interacted both with the Gram-positive and with the Gram-negative models. The dicationic photosensitizer labeled both models with a characteristic deep-red fluorescence and photoinactivated both classes of prokaryotes. In general, our study clearly demonstrates that axially ammoniumsiloxane-functionalized Si(IV) phthalocyaninates constitute excellent photosensitizers due to their weak aggregation in aqueous environments. In particular, we also show that charge-based targeting with axial ammonium groups leads toward broad-spectrum Si^IV -phthalocyanines for photodynamic inactivation of bacteria.

Current Perspective on In Vivo Molecular Imaging of Immune Cells

Contemporaneous development of improved immune cell-based therapies, and powerful imaging tools, has prompted growth in technologies for immune cell tracking in vivo. Over the past couple of decades, imaging tools such as magnetic resonance imaging (MRI) and optical imaging have successfully monitored the trafficking patterns of therapeutic immune cells and assisted the evaluation of the success or failure of immunotherapy. Recent advancements in imaging technology have made imaging an indispensable module of immune cell-based therapies. In this review, emerging applications of non-radiation imaging modalities for the tracking of a range of immune cells are discussed. Applications of MRI, NIR, and other imaging tools have demonstrated the potential of non-invasively surveying the fate of both phagocytic and non-phagocytic immune cells in vivo.

In vivo gastrointestinal drug-release monitoring through second near-infrared window fluorescent bioimaging with orally delivered microcarriers

Non-invasive monitoring of gastrointestinal drug release in vivo is extremely challenging because of the limited spatial resolution and long scanning time of existing bioimaging modalities, such as X-ray radiation and magnetic resonance. Here, we report a novel microcarrier that can retain drugs and withstand the harsh conditions of gastrointestinal tract. Significantly, we can track the microcarrier fate and semi-quantitatively monitor the content of drug released in vivo in real time by measuring the fluorescence signals in the second near-infrared window of lanthanide-based downconversion nanoparticles with an absorption competition-induced emission bioimaging system. The microcarriers show a prolonged residence time of up to 72 h in the gastrointestinal tract, releasing up to 62% of their content. Moreover, minimal deposition of the microcarriers is found in non-target organs, such as the liver, spleen and kidney. These findings provide novel insights for the development of therapeutic and bioimaging strategies of orally administered drugs.