Synthesis and Characterization of Glycoconjugated Porphyrin Triphenylamine Hybrids for Targeted Two-Photon Photodynamic Therapy

Kinetics, Equilibrium, and Thermodynamics for Conjugation of Chitosan with Insulin-Mimetic [meso-Tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-) in an Aqueous Solution

This study investigated the conjugation of chitosan with the insulin-mimetic [meso-tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-), VO(tpps), in an aqueous medium as a function of conjugation time, VO(tpps) concentrations, and temperatures. To validate the synthesis of chitosan-VO(tpps) conjugate, UV-visible and Fourier transform infrared spectrophotometric techniques were utilized. Conjugate formation is ascribed to the electrostatic interaction between the NH3+ units of chitosan and the SO3- units of VO(tpps). Chitosan enhances the stability of VO(tpps) in an aqueous medium (pH 2.5). VO(tpps) conjugation with chitosan was best explained by pseudo-second-order kinetic and Langmuir isotherm models based on kinetic and isotherm studies. The Langmuir equation determined that the maximal ability of VO(tpps) conjugated with each gram of chitosan was 39.22 μmol at a solution temperature of 45 °C. Activation energy and thermodynamic studies (Ea: 8.78 kJ/mol, ΔG: -24.52 to -27.55 kJ/mol, ΔS: 204.22 J/(mol K), and ΔH: 37.30 kJ/mol) reveal that conjugation is endothermic and physical in nature. The discharge of VO(tpps) from conjugate was analyzed in freshly prepared 0.1 mol/L phosphate buffer (pH 7.4) at 37 °C. The release of VO(tpps) from the conjugate is a two-phase process best explained by the Higuchi model, according to a kinetic analysis of the release data. Taking into consideration all experimental findings, it is proposed that chitosan can be used to formulate both solid and liquid insulin-mimetic chitosan-VO(tpps) conjugates.

Near-infrared photodynamic and photothermal co-therapy based on organic small molecular dyes

Near-infrared (NIR) organic small molecule dyes (OSMDs) are effective photothermal agents for photothermal therapy (PTT) due to their advantages of low cost and toxicity, good biodegradation, and strong NIR absorption over a wide wavelength range. Nevertheless, OSMDs have limited applicability in PTT due to their low photothermal conversion efficiency and inadequate destruction of tumor regions that are nonirradiated by NIR light. However, they can also act as photosensitizers (PSs) to produce reactive oxygen species (ROS), which can be further eradicated by using ROS-related therapies to address the above limitations of PTT. In this review, the synergistic mechanism, composition, and properties of photodynamic therapy (PDT)-PTT nanoplatforms were comprehensively discussed. In addition, some specific strategies for further improving the combined PTT and PDT based on OSMDs for cancer to completely eradicate cancer cells were outlined. These strategies include performing image-guided co-therapy, enhancing tumor infiltration, increasing H2O2 or O2 in the tumor microenvironment, and loading anticancer drugs onto nanoplatforms to enable combined therapy with phototherapy and chemotherapy. Meanwhile, the intriguing prospects and challenges of this treatment modality were also summarized with a focus on the future trends of its clinical application.

Enhanced Photodynamic Therapy: A Review of Combined Energy Sources

Photodynamic therapy (PDT) has been used in recent years as a non-invasive treatment for cancer, due to the side effects of traditional treatments such as surgery, radiotherapy, and chemotherapy. This therapeutic technique requires a photosensitizer, light energy, and oxygen to produce reactive oxygen species (ROS) which mediate cellular toxicity. PDT is a useful non-invasive therapy for cancer treatment, but it has some limitations that need to be overcome, such as low-light-penetration depths, non-targeting photosensitizers, and tumor hypoxia. This review focuses on the latest innovative strategies based on the synergistic use of other energy sources, such as non-visible radiation of the electromagnetic spectrum (microwaves, infrared, and X-rays), ultrasound, and electric/magnetic fields, to overcome PDT limitations and enhance the therapeutic effect of PDT. The main principles, mechanisms, and crucial elements of PDT are also addressed.

Synergistic chemotherapy and phototherapy based on red blood cell biomimetic nanomaterials

Novel drug delivery systems (DDSs) have become the mainstay of research in targeted cancer therapy. By combining different therapeutic strategies, potential DDSs and synergistic treatment approaches are needed to effectively deal with evolving drug resistance and the adverse effects of cancer. Nowadays, developing and optimizing human cell-based DDSs has become a new research strategy. Among them, red blood cells can be used as DDSs as they significantly enhance the pharmacokinetics of the transported drug cargo. Phototherapy, as a novel adjuvant in cancer treatment, can be divided into photodynamic therapy and photothermal therapy. Phototherapy using erythropoietic nanocarriers to mimic the unique properties of erythrocytes and overcome the limitations of existing DDSs shows excellent prospects in clinical settings. This review provides an overview of the development of photosensitizers and research on bio-nano-delivery systems based on erythrocytes and erythrocyte membranes that are used in achieving synergistic outcomes during phototherapy/chemotherapy.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

A Bio-Conjugated Chlorin-Based Metal-Organic Framework for Targeted Photodynamic Therapy of Triple Negative Breast and Pancreatic Cancers

The field of photodynamic therapy (PDT) has continued to show promise as a potential method for treating tumors. In this work a photosensitizer (PS) has been delivered to cancer cell lines for PDT by incorporation into the metal-organic framework (MOF) as an organic linker. By functionalizing the surface of MOF nanoparticles with maltotriose the PS can efficiently target cancer cells with preferential uptake into pancreatic and breast cancer cell lines. Effective targeting overcomes some current problems with PDT including long-term photosensitivity and tumor specificity. Developing a PS with optimal absorption and stability is one of the foremost challenges in PDT and the synthesis of a chlorin which is activated by long-wavelength light and is resistant to photo-bleaching is described. This chlorin-based MOF shows anti-cancer ability several times higher than that of porphyrin-based MOFs with little toxicity to normal cell lines and no dark toxicity.

Synthesis of Water-Soluble Thioglycosylated trans-A2B2 Type Porphyrins: Cellular Uptake Studies and Photodynamic Efficiency

The synthesis of water-soluble thioglycosylated A₂B₂ type porphyrins and their zinc(II) complexes is reported. The water-soluble trans-A₂B₂ porphyrins were synthesized in two steps, via [2+2] condensation between thioglycosylated dipyrromethanes and aromatic aldehydes in 15-21% yields. The thioglycosylated trans-A₂B₂ porphyrins showed decent in vitro singlet oxygen generation, which was supported by the intracellular DCFDA study. The in vitro cellular investigations of thioglycosylated A₂B₂ porphyrins were carried out in lung cancer cells (A549) to test their photodynamic therapeutic (PDT) activity. The PDT study revealed significant cytotoxicities of porphyrins with IC₅₀ values between 23.3 and 44.2 μM in the dark, whereas, after visible light exposure, the photosensitizers exhibited IC₅₀ values around 11.1-23.8 μM. The water-soluble thioglycosylated zinc(II) porphyrins having two meso-N-butylcarbazole groups exhibited an excellent degree of photocytotoxicity (IC₅₀ = 4.6-8.8 μM). The flow cytometry analysis revealed that cellular uptake and ROS (reactive oxygen species) generation efficiency of water-soluble thioglycosylated zinc(II) porphyrins were considerably higher than nonmetalated porphyrins. Confocal microscopy images displayed substantial distribution in the endoplasmic reticulum with partial colocalization in mitochondria and lysosomes of water-soluble thioglycosylated zinc(II) porphyrins in A549 cells.

Advances and perspectives in near-infrared fluorescent organic probes for surgical oncology

Surgical resection of solid tumors is currently the most efficient and preferred therapeutic strategy for treating cancer. Despite significant medical, technical, and scientific advances, the complete treatment of this lethal disease is still a challenging task. New imaging techniques and contrast agents are urgently needed to improve cytoreductive surgery and patient outcomes. Tumor-targeted probes are valuable for guiding a surgical resection of tumor from subjective judgments to visual inspection. Near-infrared (NIR) fluorescent imaging is a promising technology in preclinical and clinical tumor diagnosis and therapy. The rapid development in NIR fluorophores with improved optical properties, targeting strategies, and imaging devices has brought about prospective study of novel NIR nanomaterials for intraoperative tumor detection. In this review, we summarize the recent development in NIR-emitting organic fluorophores and cancer-targeting strategies that specifically target and accumulate in tumors for the molecular imaging of cancerous cells. We believe this technique utilizing new fluorescent probes with an intraoperative optical imaging capacity could provide a more sensitive and accurate method for cancer resection guidance, thereby resulting in better surgical outcomes. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Carbohydrates: Potential Sweet Tools Against Cancer

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Cancer, one of the most devastating degenerative diseases nowadays, is one of the main targets in Medicinal Chemistry and Pharmaceutical industry. Due to the significant increase in the incidence of cancer within world population, together with the complexity of such disease, featured with a multifactorial nature, access to new drugs targeting different biological targets connected to cancer is highly necessary.

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Among the vast arsenal of compounds exhibiting antitumor activities, this review will cover the use of carbohydrate derivatives as privileged scaffolds. Their hydrophilic nature, together with their capacity of establishing selective interactions with biological receptors located on cell surface, involved in cell-to-cell communication processes, has allowed the development of an ample number of new templates useful in cancer treatment.

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Their intrinsic water solubility has allowed their use as of pro-drug carriers for accessing more efficiently the pharmaceutical targets. The preparation of glycoconjugates in which the carbohydrate is tethered to a pharmacophore has also allowed a better permeation of the drug through cellular membranes, in which selective interactions with the carbohydrate motifs are involved. In this context, the design of multivalent structures (e.g. gold nanoparticles) has been demonstrated to enhance crucial interactions with biological receptors like lectins, glycoproteins that can be involved in cancer progression.

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Moreover, the modification of the carbohydrate structural motif, by incorporation of metal complexes, or by replacing their endocyclic oxygen, or carbon atoms with heteroatoms has led to new antitumor agents.

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Such diversity of sugar-based templates with relevant antitumor activity will be covered in this review.

Molecular engineering of a high quantum yield NIR-II molecular fluorophore with aggregation-induced emission (AIE) characteristics for in vivo imaging

NIR-II biological imaging (1000-1700 nm) has shown promise for deep tissue penetration, high spatial resolution, and low background noise. Among all the NIR-II probes, organic probes particularly attract huge attention due to their excellent stability and biocompatibility, which have the most potential for clinical translation. However, most previously reported organic NIR-II fluorescent agents often suffer from low quantum yields in aqueous solution. Herein, we developed a novel D-π-A-π-D-type NIR II chromophore XA1 with AIE characteristics based on a new design strategy for NIR-II AIE fluorophores. Owing to their intrinsic aggregation-induced emission enhancement nature, the formulated XA1 NPs show a high fluorescence quantum yield up to 14.8%, which is higher than those of most previously reported organic NIR-II fluorophores. Based on the XA1 NPs, noninvasive imaging of limb and cerebral vessels is achieved with a high signal-to-background ratio and deep penetration. Furthermore, the XA1 NPs can be used as good contrast agents for high resolution imaging of blood vessels of tumors and precise detection of tumors based on the EPR mechanism. Collectively, our work demonstrated a novel strategy for designing and manufacturing NIR-II fluorophores with AIE characteristics and proved that XA1 NPs are highly promising NIR-II probes for biomedical imaging under physiological and pathological conditions.

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.

Photosensitizers for Photodynamic Therapy

As an emerging clinical modality for cancer treatment, photodynamic therapy (PDT) takes advantage of the cytotoxic activity of reactive oxygen species (ROS) that are generated by light irradiating photosensitizers (PSs) in the presence of oxygen (O₂ ). However, further advancements including tumor selectivity and ROS generation efficiency are still required. Substantial efforts are devoted to design and synthesize smart PSs with optimized properties for achieving a desirable therapeutic efficacy. This review summarizes the recent progress in developing intelligent PSs for efficient PDT, ranging from single molecules to delicate nanomaterials. The strategies to improve ROS generation through optimizing photoinduced electron transfer and energy transfer processes of PSs are highlighted. Moreover, the approaches that combine PDT with other therapeutics (e.g., chemotherapy, photothermal therapy, and radiotherapy) and the targeted delivery in cancer cells or tumor tissue are introduced. The main challenges for the clinical application of PSs are also discussed.

Tumour-targeting photosensitisers for one- and two-photon activated photodynamic therapy

Efficient receptor-mediated delivery of a folate-targeted photosensitiser to kill cancer cells following two-photon excitation in the near-infrared is demonstrated.

Emerging Applications of Porphyrins and Metalloporphyrins in Biomedicine and Diagnostic Magnetic Resonance Imaging

In recent years, scientific advancements have constantly increased at a significant rate in the field of biomedical science. Keeping this in view, the application of porphyrins and metalloporphyrins in the field of biomedical science is gaining substantial importance. Porphyrins are the most widely studied tetrapyrrole-based compounds because of their important roles in vital biological processes. The cavity of porphyrins containing four pyrrolic nitrogens is well suited for the binding majority of metal ions to form metalloporphyrins. Porphyrins and metalloporphyrins possess peculiar photochemical, photophysical, and photoredox properties which are tunable through structural modifications. Their beneficial photophysical properties, such as the long wavelength of emission and absorption, high singlet oxygen quantum yield, and low in vivo toxicity, have drawn scientists' interest to discover new dimensions in the biomedical field. Applications of porphyrins and metalloporphyrins have been pursued in the perspective of contrast agents for magnetic resonance imaging (MRI), photodynamic therapy (PDT) of cancer, bio-imaging, and other biomedical applications. This review discusses photophysics and the photochemistry of porphyrins and their metal complexes. Secondly, it explains the current developments and mode of action for contrast agents for MRI. Moreover, the application of porphyrin and metalloporphyrin-based molecules as a photosensitizer in PDT of cancer, the mechanism of the generation of reactive oxygen species (ROS), factors that determine the efficiency of PDT, and the developments to improve this technology are delineated. The last part explores the most recent research and developments on metalloporphyrin-based materials in bio-imaging, drug delivery, and the determination of ferrochelatase in bone marrow indicating their prospective clinical applications.

Natural extracellular nanovesicles and photodynamic molecules: is there a future for drug delivery?

Photodynamic molecules represent an alternative approach for cancer therapy for their property (i) to be photo-reactive; (ii) to be not-toxic for target cells in absence of light; (iii) to accumulate specifically into tumour tissues; (iv) to be activable by a light beam only at the tumour site and (v) to exert cytotoxic activity against tumour cells. However, to date their clinical use is limited by the side effects elicited by systemic administration. Extracellular vesicles are endogenous nanosized-carriers that have been recently introduced as a natural delivery system for therapeutic molecules. We have recently shown the ability of human exosomes to deliver photodynamic molecules. Therefore, this review focussed on extracellular vesicles as a novel strategy for the delivery of photodynamic molecules at cancer sites. This completely new approach may enhance the delivery and decrease the toxicity of photodynamic molecules, therefore, represent the future for photodynamic therapy for cancer treatment.

Targeted Delivery of a Mannose-Conjugated BODIPY Photosensitizer by Nanomicelles for Photodynamic Breast Cancer Therapy

The targeted delivery of a photosensitizer (PS) with appropriate carriers represents an attractive means of selectively delivering cargo to target tissues or subcellular compartments for photodynamic therapy (PDT). Herein, a three-arm distyryl BODIPY derivative conjugated with mannose units (denoted by BTM) that can co-assemble with Tween 80 to form nanomicelles (BTM-NMs) for targeted PDT is reported. MDA-MB-231 breast cancer cells recognized and specifically internalized BTM-NMs via mannose-receptor-mediated endocytosis with preferential accumulation in the lysosomes. These NMs could disassemble in cell lysosomes and subsequently induce highly efficient singlet oxygen (¹ O₂ ) generation upon light irradiation. ¹ O₂ disrupted the lysosomal membrane and promoted the escape of BTM from the lysosome into the cytoplasm, thereby resulting in the efficient and selective killing of cancer cells through PDT. This study may provide a new strategy for designing targeted PDT systems to fight cancer.

Singlet oxygen generation properties of an inclusion complex of cyclic free-base porphyrin dimer and fullerene C60

We demonstrate that a cyclic free-base porphyrin dimer and its inclusion complex with fullerene C₆₀ possess the ability to generate singlet oxygen (¹O₂) under visible light irradiation.

Two-Photon Absorbing Phosphorescent Metalloporphyrins: Effects of π-Extension and Peripheral Substitution

The ability to form triplet excited states upon two-photon excitation is important for several applications of metalloporphyrins, including two-photon phosphorescence lifetime microscopy (2PLM) and two-photon photodynamic therapy (PDT). Here we analyzed one-photon (1P) and degenerate two-photon (2P) absorption properties of several phosphorescent Pt (II) porphyrins, focusing on the effects of aromatic π-extension and peripheral substitution on triplet emissivity and two-photon absorption (2PA). Our 2PA measurements for the first time made use of direct time-resolved detection of phosphorescence, having the ability to efficiently reject laser background through microsecond time gating. π-Extension of the porphyrin macrocycle by way of syn-fusion with two external aromatic fragments, such as in syn-dibenzo- (DBP) and syn-dinaphthoporphyrins (DNP), lowers the symmetry of the porphyrin skeleton. As a result, DBPs and DNPs exhibit stronger 2PA into the one-photon-allowed B (Soret) and Q states than fully symmetric (D4h) nonextended porphyrins. However, much more 2P-active states lie above the B state and cannot be accessed due to the interfering linear absorption. Alkoxycarbonyl groups (CO2R) in the benzo-rings dramatically enhance 2PA near the B state level. Time-dependent density functional theory (TDDFT) calculations in combinations with the sum-over-states (SOS) formalism revealed that the enhancement is due to the stabilization of higher-lying 2P-active states, which are dominated by the excitations involving orbitals extending onto the carbonyl groups. Furthermore, calculations predicted even stronger stabilization of the 2P-allowed gerade-states in symmetric Pt octaalkoxycarbonyl-tetrabenzoporphyrins. Experiments confirmed that the 2PA cross-section of PtTBP(CO2Bu)8 near 810 nm reaches above 500 GM in spite of its completely centrosymmetric structure. Combined with exceptionally bright phosphorescence (ϕphos = 0.45), strong 2PA makes Pt(II) complexes of π-extended porphyrins a valuable class of chromophores for 2P applications. Another important advantage of these porphyrinoids is their compact size and easily scalable synthesis.

Beyond the Barriers of Light Penetration: Strategies, Perspectives and Possibilities for Photodynamic Therapy

Photodynamic therapy (PDT) is a photochemistry based treatment modality that involves the generation of cytotoxic species through the interactions of a photosensitizer molecule with light irradiation of an appropriate wavelength. PDT is an approved therapeutic modality for several cancers globally and in several cases has proved to be effective where traditional treatments have failed. The key parameters that determine PDT efficacy are 1. the photosensitizer (nature of the molecules, selectivity, and macroscopic and microscopic localization etc.), 2. light application (wavelength, fluence, fluence rate, irradiation regimes etc.) and 3. the microenvironment (vascularity, hypoxic regions, stromal tissue density, molecular heterogeneity etc.). Over the years, several groups aimed to monitor and manipulate the components of these critical parameters to improve the effectiveness of PDT treatments. However, PDT is still misconstrued to be a surface treatment primarily due to the limited depths of light penetration. In this review, we present the recent advances, strategies and perspectives in PDT approaches, particularly in cancer treatment, that focus on increasing the 'damage zone' beyond the reach of light in the body. This is enabled by a spectrum of approaches that range from innovative photosensitizer excitation strategies, increased specificity of phototoxicity, and biomodulatory approaches that amplify the biotherapeutic effects induced by photodynamic action. Along with the increasing depth of understanding of the underlying physical, chemical and physiological mechanisms, it is anticipated that with the convergence of these strategies, the clinical utility of PDT will be expanded to a powerful modality in the armamentarium for the management of cancer.

Highly water-soluble and tumor-targeted photosensitizers for photodynamic therapy

Biological uses of photosensitizers in photodynamic therapy (PDT) often suffer from a lack of tumor selectivity; a strategy based on molecule-targeted cancer therapies could provide a promising solution. To synthesize new water-soluble phthalocyanines (Pcs) for bio-conjugation with peptides or antibodies, we developed a method to synthesize asymmetrically substituted Pcs with both high water solubility and one monoamino group for conjugation with biological agents for tumor homing, using folic acid as the ligand model to direct the modified Pcs into target cells. Here, we report studies on the syntheses and characterization of these Pcs. In vitro and in vivo assays prove that the high solubility characteristic can greatly increase the tumor targeting capability of Pcs by reducing non-specific uptake. This newly designed photosensitizer accumulated almost completely in tumor regions, with a negligible signal found in other tissues in the xenograft tumor model. These initial data provide strong evidence of the high specificity tumor targeting of Pcs with folate and tri-glycerol substitutions. Theoretically, the synthesized Pcs could be conveniently conjugated to many other ligands, endorsing the broad applicability of this method for tumor-targeted PDT.

Design of an amphiphilic porphyrin exhibiting high in vitro photocytotoxicity

A promising photosensitiser, which exhibits extremely suitable properties for photodynamic applications is described.

Solvent effects on static polarizability, static first hyperpolarizability and one- and two-photon absorption properties of functionalized triply twisted Möbius annulenes: a DFT study

Solvent effects on the polarizability (α), static first hyperpolarizability (β) and one- and two-photon absorption (OPA and TPA) properties of triply twisted Möbius annulenes.

Novel porphyrin–Schiff base conjugates: synthesis, characterization and in vitro photodynamic activities

Three novel porphyrin–Schiff base conjugates were synthesized and characterized. Their phototoxic activities were improved after irradiation and increased significantly with the increase of doses against A431 cells.

Nanocomposite-Based Photodynamic Therapy Strategies for Deep Tumor Treatment

Photodynamic therapy (PDT), as an emerging clinically approved modality, has been used for treatment of various cancer diseases. Conventional PDT strategies are mainly focused on superficial lesions because the wavelength of illumination light of most clinically approved photosensitizers (PSs) is located in the UV/VIS range that possesses limited tissue penetration ability, leading to ineffective therapeutic response for deep-seated tumors. The combination of PDT and nanotechnology is becoming a promising approach to fight against deep tumors. Here, the rapid development of new PDT modalities based on various smartly designed nanocomposites integrating with conventionally used PSs for deep tumor treatments is introduced. Until now many types of multifunctional nanoparticles have been studied, and according to the source of excitation energy they can be classified into three major groups: near infrared (NIR) light excited nanomaterials, X-ray excited scintillating/afterglow nanoparticles, and internal light emission excited nanocarriers. The in vitro and in vivo applications of these newly developed PDT modalities are further summarized here, which highlights their potential use as promising nano-agents for deep tumor therapy.

Synthesis and characterization of novel symmetrical two-photon chromophores derived from bis(triphenylaminotetrathienoacenyl) and fused-thiophene units

Four new donor–π–donor (D–π₁–π₂–π₁–D) fused-thiophene-based chromophores, end-functionalized with electron-donating triphenylamine (TPA) groups, were developed and characterized for a two-photon absorption study.

Synthesis and investigation of singlet oxygen production efficiency of photosensitizers based on meso-phenyl-2,5-thienylene linked porphyrin oligomers and polymers

Three new Zn(ii)-, oligo- and poly(2,5-thienylene)-linked porphyrins, bearing multiple triethylene glycol (TEG) groups were synthesized and their photophysical properties as well as singlet oxygen generation efficiencies have been investigated to elucidate the possibility of their use as a photosensitizer.

A series of triphenylamine-based two-photon absorbing materials with AIE property for biological imaging

One- and two-photon fluorescence properties of six chromophores were successfully tuned by a simple structure modification. The chromophore3Bwith significant AIE and 2PA effect shows promise in bioimaging applications.