Tumor cell loaded thermosensitive hydrogel for photodynamic therapy associated tumor antigens release

BACKGROUND

Immunotherapy is a powerful strategy for treating cancer and can be used to inhibit the post-surgical relapse of tumors.

METHODS

To achieve this, a Cell@hydrogel was developed as a template using a mixture of CT26 tumor cells and Pluronic® F-127/gelatin.

RESULTS

The proposed mixture has a solution-to-gelation functionality and vice versa. The morphology of the Cell@hydrogel was characterized by scanning electron microscopy and confocal microscopy. For photodynamic immunotherapy, the Cell@hydrogel was functionalized with Cy7 (Cy7-Cell@hydrogel) to quantify reactive oxygen species in CT26 tumor cells. Gel electrophoresis and membrane integrity tests were performed to determine the efficiency of the Cy7-Cell@hydrogel following photodynamic therapy.

CONCLUSIONS

This protocol provides an alternative approach that mechanistically inhibits the post-surgical relapse of solid tumors based on immunotherapy.

Antimicrobial Photodynamic Therapy Using Encapsulated Protoporphyrin IX for the Treatment of Bacterial Pathogens

Herein, we report on the antimicrobial photodynamic effect of polymeric nanoparticles containing the endogenous photosensitizer protoporphyrin IX. Compared to equivalent doses of the free photosensitizer, we demonstrated that the photodynamic antimicrobial efficacy of PLGA (polylactic-co-glycolic acid) nanoparticles containing protoporphyrin IX (PpIX) against pathogenic Staphylococcus aureus (S. aureus) is preserved after encapsulation, while photobleaching is reduced. In addition, compared to equivalent doses of the free porphyrin, we show that a reduction in the cytotoxicity in mammalian cell cultures is observed when encapsulated. Therefore, the encapsulation of protoporphyrin IX reduces its photodegradation, while the released photosensitizer maintains its ability to generate reactive oxygen species upon light irradiation. The polymeric nanoencapsulation promotes aqueous solubility for the hydrophobic PpIX, improves its photostability and reduces the cytotoxicity, while providing an extended release of this endogenous photosensitizer.

Anti-Cancer Effect of Chlorophyllin-Assisted Photodynamic Therapy to Induce Apoptosis through Oxidative Stress on Human Cervical Cancer

Photodynamic therapy is an alternative approach to treating tumors that utilizes photochemical reactions between a photosensitizer and laser irradiation for the generation of reactive oxygen species. Currently, natural photosensitive compounds are being promised to replace synthetic photosensitizers used in photodynamic therapy because of their low toxicity, lesser side effects, and high solubility in water. Therefore, the present study investigated the anti-cancer efficacy of chlorophyllin-assisted photodynamic therapy on human cervical cancer by inducing apoptotic response through oxidative stress. The chlorophyllin-assisted photodynamic therapy significantly induced cytotoxicity, and the optimal conditions were determined based on the results, including laser irradiation time, laser power density, and chlorophyllin concentration. In addition, reactive oxygen species generation and Annexin V expression level were detected on the photodynamic reaction-treated HeLa cells under the optimized conditions to evaluate apoptosis using a fluorescence microscope. In the Western blotting analysis, the photodynamic therapy group showed the increased protein expression level of the cleaved caspase 8, caspase 9, Bax, and cytochrome C, and the suppressed protein expression level of Bcl-2, pro-caspase 8, and pro-caspase 9. Moreover, the proposed photodynamic therapy downregulated the phosphorylation of AKT1 in the HeLa cells. Therefore, our results suggest that the chlorophyllin-assisted photodynamic therapy has potential as an antitumor therapy for cervical cancer.

Nanoconstructs for theranostic application in cancer: Challenges and strategies to enhance the delivery

Nanoconstructs are made up of nanoparticles and ligands, which can deliver the loaded cargo at the desired site of action. Various nanoparticulate platforms have been utilized for the preparation of nanoconstructs, which may serve both diagnostic as well as therapeutic purposes. Nanoconstructs are mostly used to overcome the limitations of cancer therapies, such as toxicity, nonspecific distribution of the drug, and uncontrolled release rate. The strategies employed during the design of nanoconstructs help improve the efficiency and specificity of loaded theranostic agents and make them a successful approach for cancer therapy. Nanoconstructs are designed with a sole purpose of targeting the requisite site, overcoming the barriers which hinders its right placement for desired benefit. Therefore, instead of classifying modes for delivery of nanoconstructs as actively or passively targeted systems, they are suitably classified as autonomous and nonautonomous types. At large, nanoconstructs offer numerous benefits, however they suffer from multiple challenges, too. Hence, to overcome such challenges computational modelling methods and artificial intelligence/machine learning processes are being explored. The current review provides an overview on attributes and applications offered by nanoconstructs as theranostic agent in cancer.

An aptamer-based magnetic resonance imaging contrast agent for detecting oligomeric amyloid-β in the brain of an Alzheimer's disease mouse model

The oligomeric amyloid-β (oAβ) is a reliable feature for an early diagnosis of Alzheimer's disease (AD). Therefore, the objective of this study was to demonstrate imaging of oAβ deposits using our developed DNA aptamer called ob5 conjugated with gadolinium (Gd)-dodecane tetraacetic acid (DOTA) as a contrast agent for early diagnosis of AD using MRI. An oAβ-specific aptamer was developed by amide bond formation and conjugated to Gd-DOTA MRI contrast agent and/or cyanine5 (cy5). We verified the performance of our new contrast agent with an AD mouse model using in vivo and ex vivo fluorescent imaging and animal MRI experiments. The presence of soluble Aβ in 3xTg AD mice was detected using GdDOTA-ob5-cy5 probe ex vivo. Fluorescence intensities of the GdDOTA-ob5-cy5 contrast agent were high in the brains of 3xTg-AD mice, but relatively low in the brains of control mice. The GdDOTA-ob5 contrast agent had higher relaxivity than a clinically available contrast agent. T1-weighted MRI signals in 5-month-old 3xTg AD mice increased at 5 min, were prolonged until 10 min, then decreased 15 min after injecting the GdDOTA-ob5 contrast agent. Our targeted DNA aptamer GdDOTA-ob5 contrast agent could be potentially useful for validating the efficacy of a novel diagnostic contrast agent for selectively targeting neurotoxic oAβ. It could ultimately be used for early diagnosis of AD.

Nanoemulsion applications in photodynamic therapy

Nanoemulsion, or nanoscaled-size emulsions, is a thermodynamically stable system formed by blending two immiscible liquids, blended with an emulsifying agent to produce a single phase. Nanoemulsion science has advanced rapidly in recent years, and it has opened up new opportunities in a variety of fields, including pharmaceuticals, biotechnology, food, and cosmetics. Nanoemulsion has been recognized as a potential drug delivery technology for various drugs, such as photosensitizing agents (PS). In photodynamic therapy (PDT), PSs produce cytotoxic reactive oxygen species under specific light irradiation, which oxidize the surrounding tissues. Over the past decades, the idea of PS-loaded nanoemulsions has received researchers' attention due to their ability to overcome several limitations of common PSs, such as limited permeability, non-specific phototoxicity, hydrophobicity, low bioavailability, and self-aggregation tendency. This review aims to provide fundamental knowledge of nanoemulsion formulations and the principles of PDT. It also discusses nanoemulsion-based PDT strategies and examines nanoemulsion advantages for PDT, highlighting future possibilities for nanoemulsion use.

pH-Responsive Hyperbranched Polymer Nanoparticles to Combat Intracellular Infection by Disrupting Bacterial Wall and Regulating Macrophage Polarization

Intracellular bacterial infections pose a serious threat to public health. Macrophages are a heterogeneous population of immune cells that play a vital role in intracellular bacterial infection. However, bacteria that survive inside macrophages could subvert the cell signaling and eventually reduce the antimicrobial activity of macrophages. Herein, dual pH-responsive polymer (poly[(3-phenylprop-2-ene-1,1-diyl)bis(oxy)bis(enthane-2,1-diyl)diacrylate-co-N-aminoethylpiperazine] (PCA)) nanoparticles were developed to clear intracellular bacteria by activating macrophages and destructing bacterial walls. The presence of acid-labile acetal linkages and tertiary amine groups in the polymer's backbone endow hyperbranched PCA dual pH-response activity that shows acid-induced positive charge increase and cinnamaldehyde release properties. The biodegraded PCA nanoparticles could significantly inhibit the growth of bacteria by damaging the bacterial walls. Meanwhile, PCA nanoparticles could uptake by macrophages, generate reactive oxygen species (ROS), and remodel the immune response by upregulating M1 polarization, leading to the reinforced antimicrobial capacity. Furthermore, PCA nanoparticles could promote bacteria-infected wound healing in vivo. Therefore, these dual pH-responsive PCA nanoparticles enabling bacteria-killing and macrophage activation provide a novel outlook for treating intracellular infection.

Secure transplantation by tissue purging using photodynamic therapy to eradicate malignant cells

The field of photodynamic therapy (PDT) for treating various malignant neoplasms has been given researchers' attention due to its ability to be a selective and minimally invasive cancer therapy strategy. The possibility of tumor cell infection and hence high recurrence rates in cancer patients tends to restrict autologous transplantation. So, the photodynamic tissue purging process, which consists of selective photoinactivation of the malignant cells in the graft, is defined as a compromising strategy to purify contaminated tissues before transplantation. In this strategy, the direct malignant cells' death results from the reactive oxygen species (ROS) generation through the activation of a photosensitizer (PS) by light exposure in the presence of oxygen. Since new PS generations can effectively penetrate the tissue, PDT could be an ideal ex vivo tissue purging protocol that eradicates cancer cells derived from various malignancies. The challenge is that the applied pharmacologic ex vivo tissue purging should efficiently induce tumor cells with minor influence on normal tissue cells. This review aims to provide an overview of the current status of the most effective PDT strategies and PS development concerning their potential application in ex vivo purging before hematopoietic stem cell or ovarian tissue transplantation.

Self-assembling, pH-responsive nanoflowers for inhibiting PAD4 and neutrophil extracellular trap formation and improving the tumor immune microenvironment

Self-assembling carrier-free nanodrugs are attractive agents because they accumulate at tumor by an enhanced permeability and retention (EPR) effect without introduction of inactive substances, and some nanodrugs can alter the immune environment. We synthesized a peptidyl arginine deiminase 4 (PAD4) molecular inhibitor, ZD-E-1M. It could self-assembled into nanodrug ZD-E-1. Using confocal laser scanning microscopy, we observed its cellular colocalization, PAD4 activity and neutrophil extracellular traps (NETs) formation. The populations of immune cells and expression of immune-related proteins were determined by single-cell mass cytometry. ZD-E-1 formed nanoflowers in an acidic environment, whereas it formed nanospheres at pH 7.4. Accumulation of ZD-E-1 at tumor was pH-responsive because of its pH-dependent differences in the size and shape. It could enter the nucleus and bind to PAD4 to prolong the intracellular retention time. In mice, ZD-E-1 inhibited tumor growth and metastasis by inhibiting PAD4 activity and NETs formation. Besides, ZD-E-1 could regulate the ratio of immune cells in LLC tumor-bearing mice. Immunosuppressive proteins like LAG3 were suppressed, while IFN-γ and TNF-α as stimulators of tumor immune response were upregulated. Overall, ZD-E-1 is a self-assembling carrier-free nanodrug that responds to pH, inhibits PAD4 activity, blocks neutrophil extracellular traps formation, and improves the tumor immune microenvironment.

Knee Osteoarthritis Therapy: Recent Advances in Intra-Articular Drug Delivery Systems

Drug delivery for osteoarthritis (OA) treatment is a continuous challenge because of their poor bioavailability and rapid clearance in joints. Intra-articular (IA) drug delivery is a common strategy and its therapeutic effects depend mainly on the efficacy of the drug-delivery system used for OA therapy. Different types of IA drug-delivery systems, such as microspheres, nanoparticles, and hydrogels, have been rapidly developed over the past decade to improve their therapeutic effects. With the continuous advancement in OA mechanism research, new drugs targeting specific cell/signaling pathways in OA are rapidly evolving and effective drug delivery is critical for treating OA. In this review, recent advances in various IA drug-delivery systems for OA treatment, OA targeted strategies, and related signaling pathways in OA treatment are summarized and analyzed based on current publications.

Self-Assembled Nanoparticles for Tumor-Triggered Targeting Dual-Mode NIRF/MR Imaging and Photodynamic Therapy Applications

In this study, the self-assembling strategy was used to synthesize a therapeutic and diagnostic nanosystem for tumor-triggered targeting dual-mode near-infrared fluorescence (NIRF)/magnetic resonance (MR) imaging and photodynamic therapy applications. This theranostic nanosystem was synthesized based on the self-assembling of the short peptide (PLGVRGRGDC) and the gadolinium chelator (diethylenetriamine pentaacetic acid) functionalized amphiphilic DSPE-PEG₂₀₀₀, followed by loading with the insoluble photosensitizer therapeutic agent chlorin e6 (Ce6). The formed theranostic nanosystem can accumulate in the matrix metalloproteinase 2 (MMP2) rich tumor sites guided by the enhanced permeability and retention effect and MMP2-substrate peptide (PLGVR) targeting. After PLGVR was hydrolyzed in the tumor microenvironment by MMP2, the nanosystem was actively taken up by tumor cells via Arg-Gly-Asp (RGD) peptide-mediated internalization. With the coexistence of gadolinium and Ce6, the formed nanosystem can be used for both NIRF/MR dual-mode imaging and photodynamic therapy. These tumor-triggered targeting self-assembled nanoparticles with low cytotoxicity and high endocytosis efficiency can efficiently induce A549 cancer cell apoptosis under laser irradiation. Meanwhile, they possessed enhanced tumor-targeted NIRF/MR imaging ability and efficiently inhibited tumor growth with minimal side effects in mice bearing A549 lung cancer. Therefore, these self-assembled theranostic nanoparticles may have great potential for cancer clinical diagnosis and therapy.

Photodynamic cancer therapy using liposomes as an advanced vesicular photosensitizer delivery system

The multidisciplinary field of photodynamic therapy (PDT) is a combination of photochemistry and photophysics sciences, which has shown tremendous potential for cancer therapy application. PDT employs a photosensitizing agent (PS) and light to form cytotoxic reactive oxygen species and subsequently oxidize light-exposed tissue. Despite numerous advantages of PDT and enormous progress in this field, common PSs are still far from ideal treatment because of their poor permeability, non-specific phototoxicity, side effects, hydrophobicity, weak bioavailability, and tendency to self-aggregation. To circumvent these limitations, PS can be encapsulated in liposomes, an advanced drug delivery system that has demonstrated the ability to enhance drug permeability into biological membranes and loading both hydrophobic and lipophilic agents. Moreover, liposomes can also be coated by targeting agents to improve delivery efficiency. The present review aims to summarize the principles of PDT, various PS generations, PS-loaded nanoparticles, liposomes, and their impact on PDT, then discuss recent photodynamic cancer therapy strategies using liposomes as PS-loaded vectors, and highlight future possibilities and perspectives.

Recent Progress in Stimuli-Responsive Intelligent Nano Scale Drug Delivery Systems: A Special Focus Towards pH-Sensitive Systems

Stimuli-responsive nanocarriers are gaining much attention due to their versatile multifunctional activities, including disease diagnosis and treatment. Recently, clinical applications of nano-drug delivery systems for cancer treatment pose a challenge due to their limited cellular uptake, low bioavailability, poor targetability, stability issues, and unfavourable pharmacokinetics. To overcome these issues, researchers are focussing on stimuli-responsive systems. Nanocarriers elicit their role through endogenous (pH, temperature, enzyme, and redox) or exogenous (temperature, light, magnetic field, ultrasound) stimulus. These systems were designed to overcome the shortcomings such as non-specificity and toxicity associated with the conventional drug delivery systems. The pH variation between healthy cells and tumor microenvironment creates a platform for the generation of pH-sensitive nano delivery systems. Herein, we propose to present an overview of various internal and external stimuli-responsive behavior-based drug delivery systems. Herein, the present review will focus specifically on the significance of various pH-responsive nanomaterials such as polymeric nanoparticles, nano micelles, inorganic-based pH-sensitive drug delivery carriers such as calcium phosphate nanoparticles, and carbon dots in cancer treatment. Moreover, this review elaborates the recent findings on pH-based stimuli-responsive drug delivery systems with special emphasis on our reported stimuli-responsive systems for cancer treatment.

Current Nanoparticle-Based Technologies for Osteoarthritis Therapy

Osteoarthritis (OA) is a common chronic joint disease that is characterized by joint pain and stiffness, and limitation of motion and the major cause of disability, which reduces life quality of patients and brings a large economic burden to the family and society. Current clinical treatment is mostly limited to symptomatic treatment aimed at pain alleviation and functional improvement, rather than suppressing the progression of OA. Nanotechnology is a promising strategy for the treatment of OA. In this review, we summarize the current experimental progress that focuses on technologies such as liposomes, micelles, dendrimers, polymeric nanoparticles (PNPs), exosomes, and inorganic nanoparticles (NPs) for their potential treatment of OA.

Conjugated Photosensitizers for Imaging and PDT in Cancer Research

Early cancer detection and perfect understanding of the disease are imperative toward efficient treatments. It is straightforward that, for choosing a specific cancer treatment methodology, diagnostic agents undertake a critical role. Imaging is an extremely intriguing tool since it assumes a follow up to treatments to survey the accomplishment of the treatment and to recognize any conceivable repeating injuries. It also permits analysis of the disease, as well as to pursue treatment and monitor the possible changes that happen on the tumor. Likewise, it allows screening the adequacy of treatment and visualizing the state of the tumor. Additionally, when the treatment is finished, observing the patient is imperative to evaluate the treatment methodology and adjust the treatment if necessary. The goal of this review is to present an overview of conjugated photosensitizers for imaging and therapy.

Adenine-Functionalized Supramolecular Micelles for Selective Cancer Chemotherapy

Functional supramolecular micelles containing self-complementary multiple hydrogen bonding adenine groups (A-PPG) can spontaneously self-assemble into stable nanosized micelles in aqueous solution. These micelles can be used to selectively deliver anticancer drugs to cancer cells and effectively promote tumor cell death via apoptosis, without harming normal cells. The drug-loaded micelles exhibit tunable drug-loading capacity and rapid pH-triggered drug release under acidic conditions, as well as a high drug-entrapment stability in serum-rich media due to the reversible hydrogen-bonded adenine-adenine interactions within the micellar interior; these properties are critical to achieving effective chemotherapeutic drug delivery and controlled drug release. In vitro assays show that the drug-loaded micelles exert significant cytotoxic effects on cancer cells, with minimal effects on normal cells under physiological conditions. Cytotoxicity assays using A-PPG micelles loaded with different anticancer drugs confirm these effects. Importantly, cellular internalization and flow cytometric analyses demonstrate that the adenine moieties within A-PPG micelles significantly increase selective endocytic uptake of the supramolecular micelles by cancer cells, which in turn induce apoptotic cell death and substantially enhance the response to chemotherapy. Thus, A-PPG micelles can improve the safety and efficacy of cancer chemotherapy.

Magnetic stomatocyte-like nanomotor as photosensitizer carrier for photodynamic therapy based cancer treatment

Amphiphilic block copolymer can self-assemble to stomatocyte-like structure as drug delivery carrier. Photodynamic therapy (PDT) is an emerging modality for cancer treatment. However, PDT has various problems, such as weak tumor accumulation ability of photosensitizers (PSs), short lifetime of singlet oxygen (¹O₂, main reactive oxygen species in PDT) and tumor hypoxia microenvironment, to restrict its therapeutic efficacy. To convey PSs to tumor tissues and improve PDT efficacy, iron oxide nanoparticles (IONPs) were loaded inside the self-assembly stomatocytes-like structure of poly(ethylene glycol) block polystyrene (PEG-b-PS) as nanomotors (IONPs loaded stomatocytes nanomotors, denoted IS-NMs) for PS (zinc phthalocyanine, ZnPc) delivery. The hybrid nanomotors (iron oxide nanoparticles loaded stomatocytes@ZnPc nanomotors, denoted ISP-NMs) can be gathered in tumor tissues under magnetic field owing to magnetism of IONPs. After been trapped by cancer cells, IONPs can catalyze decomposition of endogenous H₂O₂ to generate O₂ as propelling force for ISP-NMs movement. The motion characteristics of ISP-NMs expanded the distribution of ZnPc to enlarge ROS reactive distribution and enhance the activity of PDT. And the generated O₂ can be supplied for PDT process to ensure its high-performance. Furthermore, ISP-NMs have nuclear magnetic resonance imaging (MRI) function since IONPs are efficient T₂ contrast agent.

The Red Color of Life Transformed - Synthetic Advances and Emerging Applications of Protoporphyrin IX in Chemical Biology

Protoporphyrin IX (PPIX) is the porphyrin scaffold of heme b, a ubiquitous prosthetic group of proteins responsible for oxygen binding (hemoglobin, myoglobin), electron transfer (cytochrome c) and catalysis (cytochrome P450, catalases, peroxidases). PPIX and its metallated derivatives frequently find application as therapeutic agents, imaging tools, catalysts, sensors and in light harvesting. The vast toolkit of accessible porphyrin functionalization reactions enables easy synthetic modification of PPIX to meet the requirements for its multiple uses. In the past few years, particular interest has arisen in exploiting the interaction of PPIX and its synthetic derivatives with biomolecules such as DNA and heme-binding proteins to evolve molecular devices with new functions as well as to uncover potential therapeutic toeholds. This review strives to shine a light on the most recent developments in the synthetic chemistry of PPIX and its uses in selected fields of chemical biology.

Antitumor immunity triggered by photothermal therapy and photodynamic therapy of a 2D MoS2 nanosheet-incorporated injectable polypeptide-engineered hydrogel combinated with chemotherapy for 4T1 breast tumor therapy

A multifunctional PC₁₀A/DOX/MoS₂ hydrogel was designed and prepared for chemotherapy/photothermal therapy/photodynamic therapy of 4T1 tumor, and the immune responses triggered by photothermal and photodynamic effect of MoS₂ nanosheet in the hydrogel were also studied. Positively charged DOX and negatively charged PC₁₀A were loaded on the surface of MoS₂ nanosheet through layer-by-layer method to prepare hybrid PC₁₀A/DOX/MoS₂ nanoparticles. PC₁₀A/DOX/MoS₂ nanoparticles were dispersed in PC₁₀A hydrogel to prepare PC₁₀A/DOX/MoS₂ hydrogel. 2D MoS₂ nanosheet in the hydrogel was simultaneously utilized as photothermal agent and photodynamic agent for the generation of hyperthermia and reactive oxygen species, respectively. This PC₁₀A/DOX/MoS₂ hydrogel was injectable and possessed excellent biocompatibility. The results of in vivo tumor-bearing mice experiments showed that a remarkably enhance tumor inhibition was observed by the combination of chemo-photothermal-photodynamic therapy compared with photothermal therapy, photodynamic therapy, or chemotherapy alone. In addition, the results of in vivo therapy exhibited that the PC₁₀A/DOX/MoS₂ hydrogel with laser irradiation could activate antitumor immune effects to suppress the growth of primary 4T1 breast tumors and distal lung metastatic nodules. Therefore, these results demonstrated that the PC₁₀A/DOX/MoS₂ hydrogel was promising to be utilized in antitumor immunity therapy triggered by photothermal therapy and photodynamic therapy for malignant tumor.

Multi-mode biodegradable tumour-microenvironment sensitive nanoparticles for targeted breast cancer imaging

Gas-filled ultrasound (US) contrast agents easily collapse in the body, and the gas can easily overflow, which limits the effectiveness of US imaging. To address this issue, an injectable gas-generating multi-mode system was developed that carries the MR negative contrast agent Fe3O4, the fluorescent dye Cy5.5, and the CO2 releasing donor (Na2CO3). The nanoparticles can continuously generate carbon dioxide (CO2) gas in acidic tumour tissue in the body, giving the tumour a strong echo signal under ultrasonic imaging. In addition, the nanoparticles confer excellent effects for MR and fluorescence imaging of the tumour tissue. The results indicate that this pH-responsive NP system provides good effects in MR/US/fluorescent imaging. This study provides a useful reference for multi-mode tumour imaging.

Acid-activatable polymeric curcumin nanoparticles as therapeutic agents for osteoarthritis

Curcumin, a primary active element of turmeric, has potent antioxidant and anti-inflammatory activity, but its low bioavailability is a major hurdle in its pharmaceutical applications. To enhance the therapeutic efficacy of curcumin, we exploited polymeric prodrug strategy. Here, we report rationally designed acid-activatable curcumin polymer (ACP), as a therapeutic prodrug of curcumin, in which curcumin was covalently incorporated in the backbone of amphiphilic polymer. ACP could self-assemble to form micelles that rapidly release curcumin under the acidic condition. The potential of ACP micelles as therapeutics for osteoarthritis was evaluated using a mouse model of monoidoacetic acid (MIA)-induced knee osteoarthritis. ACP micelles drastically protected the articular structures from arthritis through the suppression of tumor necrosis factor-alpha (TNF-α) and interleukin 1β (IL-1β). Given their pathological stimulus-responsiveness and potent antioxidant and anti-inflammatory activities, ACP micelles hold remarkable potential as a therapeutic agent for not only osteoarthritis but also various inflammatory diseases.

Sharp pH-responsive mannose prodrug polypeptide nanoparticles encapsulating a photosensitizer for enhanced near infrared imaging-guided photodynamic therapy

Mannose has been reported as a novel drug to kill cancer cells. The prodrug of mannose will promote its targeted delivery and enrichment at the tumor site and cancer cells. Here, a pH-sensitive polypeptide copolymer with a tertiary amine group has been prepared and a mannose molecule was conjugated to the polymer through the formation of a Schiff base. At the same time, an iodinated boron dipyrromethene (BDPI) photosensitizer with high singlet oxygen generation efficacy and near infrared (NIR) fluorescence was encapsulated by the nanoparticles, which makes it a potential pH-sensitive NIR imaging-guided chemotherapy/PDT agent. In vitro and in vivo studies reveal that in a tumor acidic environment, the protonation of the tertiary amine group destroyed the nanostructure of the nanoparticles, resulting in increased BDPI release. Meanwhile, the bond cleavage of the Schiff base led to the release of conjugated mannose and synergistic inhibition of tumor cell growth with the PDT effect was realized. The combination of these two kinds of tumor suppression effects and photodynamic therapy made this pH-sensitive polypeptide delivery system show great potential for further cancer therapy.

Enhancement of Photodynamic Cancer Therapy by Physical and Chemical Factors

The viable use of photodynamic therapy (PDT) in cancer therapy has never been fully realized because of its undesirable effects on healthy tissues. Herein we summarize some physicochemical factors that can make PDT a more viable and effective option to provide future oncological patients with better-quality treatment options. These physicochemical factors include light sources, photosensitizer (PS) carriers, microwaves, electric fields, magnetic fields, and ultrasound. This Review is meant to provide current information pertaining to PDT use, including a discussion of in vitro and in vivo studies. Emphasis is placed on the physicochemical factors and their potential benefits in overcoming the difficulty in transitioning PDT into the medical field. Many advanced techniques, such as employing X-rays as a light source, using nanoparticle-loaded stem cells and bacteriophage bio-nanowires as a photosensitizer carrier, as well as integration with immunotherapy, are among the future directions.

A Review on (Hydro)Porphyrin-Loaded Polymer Micelles: Interesting and Valuable Platforms for Enhanced Cancer Nanotheranostics

Porphyrins are known therapeutic agents for photodynamic therapy of cancer and also imaging agents for NIR fluorescence imaging, MRI, or PET. A combination of interesting features makes tetrapyrrolic macrocycles suitable for use as theranostic agents whose full potential can be achieved using nanocarriers. This review provides an overview on nanotheranostic agents based on polymeric micelles and porphyrins developed so far.

Evolution of Nanoparticle-Mediated Photodynamic Therapy: From Superficial to Deep-Seated Cancers

Enthusiasm for photodynamic therapy (PDT) as a potential therapeutic intervention for cancer has increased exponentially in recent decades. Photodynamic therapy constitutes a clinically approved, minimally invasive treatment modality that uses a photosensitizer (light absorbing molecule) and light to kill cancer cells. The principle of PDT is, when irradiated with a light of a suitable wavelength, a photosensitizer absorbs the light energy and generates cytotoxic free radicals through various mechanisms. The overall efficiency of PDT depends on characteristics of activation light and in-situ dosimetry, including the choice of photosensitizer molecule, wavelength of the light, and tumor location and microenvironment, for instance, the use of two-photon laser or an X-ray irradiator as the light source increases tissue-penetration depth, enabling it to achieve deep PDT. In this mini-review, we discuss the various designs and strategies for single, two-photon, and X-ray-mediated PDT for improved clinical outcomes.

Synthesis and Encapsulation of a New Zinc Phthalocyanine Photosensitizer into Polymeric Nanoparticles to Enhance Cell Uptake and Phototoxicity

Efforts to enhance the utility of photodynamic therapy as a non-invasive method for treating certain cancers have often involved the design of dye sensitizers with increased singlet oxygen efficiency. More recently, however, sensitizers with greater selectivity for tumor cells than surrounding tissue have been targeted. The present study provides an approach to the modification of the known photosensitizer zinc phthalocyanine (ZnPc), to enhance its solubility and delivery to cancer cells. Targeting a photosensitizer to the site of action improves the efficacy of the sensitizer in photodynamic therapy. In this work we used PLGA-b-PEG to encapsulate a new zinc phthalocyanine derivative, 2(3), 9(10), 16(17), 23(24)-tetrakis-(4’-methyl-benzyloxy) phthalocyanine zinc(II) (ZnPcBCH3), to enhance uptake into A549 cells, a human lung cancer cell line. ZnPcBCH3 exhibited the same photochemical properties as the parent compound ZnPc but gave increased solubility in organic solvents, which allowed for efficient encapsulation. In addition, the encapsulated dye showed a near 500-fold increase in phototoxicity for A549 cancer cells compared to free dye.

Poly(β-Amino Esters): Synthesis, Formulations, and Their Biomedical Applications

Poly(β-amino ester) (abbreviated as PBAE or PAE) refers to a polymer synthesized from an acrylate and an amine by Michael addition and has properties inherent to tertiary amines and esters, such as pH responsiveness and biodegradability. The versatility of building blocks provides a library of polymers with miscellaneous physicochemical and mechanical properties. When used alone or together with other materials, PBAEs can be fabricated into different formulations in order to fulfill various requirements in drug delivery (for instance, gene, anticancer drugs, and antimicrobials delivery) and natural complex mimicry (nanochaperones). This progress report discusses the recent developments in design, synthesis, formulations, and applications of PBAEs in biomedical fields and provides a perspective view for the future of the PBAEs.

Functional Polymer Nanocarriers for Photodynamic Therapy

Photodynamic therapy (PDT) is an appealing therapeutic modality in management of some solid tumors and other diseases for its minimal invasion and non-systemic toxicity. However, the hydrophobicity and non-selectivity of the photosensitizers, inherent serious hypoxia of tumor tissues and limited penetration depth of light restrict PDT further applications in clinic. Functional polymer nanoparticles can be used as a nanocarrier for accurate PDT. Here, we elucidate the mechanism and application of PDT in cancer treatments, and then review some strategies to administer the biodistribution and activation of photosensitizers (PSs) to ameliorate or utilize the tumor hypoxic microenvironment to enhance the photodynamic therapy effect.

Self-Assembly of Monomeric Hydrophobic Photosensitizers with Short Peptides Forming Photodynamic Nanoparticles with Real-Time Tracking Property and without the Need of Release in Vivo

Employing nanoscaled materials as photosensitizer (PS) carriers is an effective strategy to solve the problem of poor solubility and low tumor selectivity of hydrophobic PS in photodynamic therapy (PDT), which compulsorily requires the PS release in PDT implementation. However, the complicated environment in vivo makes it difficult to precisely design and control the release process and the delivery process requires real-time tracking. Developing a delivery strategy of hydrophobic PS in the monomeric form with fluorescent emission and without consideration of the PS release in the PDT process, is in urgent demand. Herein, we report a versatile and potent strategy for fabrication of photodynamic nanoparticles (nanoPSs) with featuring the monomeric PS based on aromatic peptide-modulated self-assembly of porphyrin derivatives. Aromatic peptides within nanoPSs can isolate hydrophobic porphyrins from each other, resulting in monomeric porphyrin delivery with real-time fluorescence tracking property and avoiding self-aggregation and hence porphyrin release. Moreover, partially charged porphyrins tend to expose on the surface of nanoPSs, facilitating production and diffusion of ¹O₂. The highest ¹O₂ yield can be achieved with porphyrin loading as low as 6 wt %, reducing side effects of excessive porphyrin injection. The nanoPSs show enhanced PDT efficacy in vitro and in vivo leading to complete tumor eradication. This study highlights opportunities for development of active photodynamic nanoparticles and provides an alternative strategy for delivery of hydrophobic photosensitive drugs with enhanced therapeutic effects.

Theranostics and metabolotheranostics for precision medicine in oncology

Most diseases, especially cancer, would significantly benefit from precision medicine where treatment is shaped for the individual. The concept of theragnostics or theranostics emerged around 2002 to describe the incorporation of diagnostic assays into the selection of therapy for this purpose. Increasingly, theranostics has been used for strategies that combine noninvasive imaging-based diagnostics with therapy. Within the past decade theranostic imaging has transformed into a rapidly expanding field that is located at the interface of diagnosis and therapy. A critical need in cancer treatment is to minimize damage to normal tissue. Molecular imaging can be applied to identify targets specific to cancer with imaging, design agents against these targets to visualize their delivery, and monitor response to treatment, with the overall purpose of minimizing collateral damage. Genomic and proteomic profiling can provide an extensive 'fingerprint' of each tumor. With this cancer fingerprint, theranostic agents can be designed to personalize treatment for precision medicine of cancer, and minimize damage to normal tissue. Here, for the first time, we have introduced the term 'metabolotheranostics' to describe strategies where disease-based alterations in metabolic pathways detected by MRS are specifically targeted with image-guided delivery platforms to achieve disease-specific therapy. The versatility of MRI and MRS in molecular and functional imaging makes these technologies especially important in theranostic MRI and 'metabolotheranostics'. Our purpose here is to provide insights into the capabilities and applications of this exciting new field in cancer treatment with a focus on MRI and MRS.

Stimuli-responsive polymeric micelles for drug delivery and cancer therapy

Polymeric micelles (PMs) have been widely investigated as nanocarriers for drug delivery and cancer treatments due to their excellent physicochemical properties, drug loading and release capacities, facile preparation methods, biocompatibility, and tumor targetability. They can be easily engineered with various functional moieties to further improve their performance in terms of bioavailability, circulation time, tumor specificity, and anticancer activity. The stimuli-sensitive PMs capable of responding to various extra- and intracellular biological stimuli (eg, acidic pH, altered redox potential, and upregulated enzyme), as well as external artificial stimuli (eg, magnetic field, light, temperature, and ultrasound), are considered as “smart” nanocarriers for delivery of anticancer drugs and/or imaging agents for various therapeutic and diagnostic applications. In this article, the recent advances in the development of stimuli-responsive PMs for drug delivery, imaging, and cancer therapy are reviewed. The article covers the generalities of stimuli-responsive PMs with a focus on their major delivery strategies and newly emerging technologies/nanomaterials, discusses their drawbacks and limitations, and provides their future perspectives.

pH-responsive gold nanoclusters-based nanoprobes for lung cancer targeted near-infrared fluorescence imaging and chemo-photodynamic therapy

Nanoparticle-based drug delivery systems have drawn a great deal of attention for their opportunities to improve cancer treatments over intrinsic limits of conventional cancer therapies. Herein, we developed the polypeptide-modified gold nanoclusters (GNCs)-based nanoprobes for tumor-targeted near-infrared fluorescence imaging and chemo-photodynamic therapy. The nanoprobes comprise of tetra-functional components: i) polyethylene glycol (PEG) shell for long blood circulation and better biocompatibility; ii) MMP2 polypeptide (CPLGVRGRGDS) for tumor targeting; iii) cis-aconitic anhydride-modified doxorubicin (CAD) for pH-sensitive drug release; iv) photosensitizer chlorin e6 (Ce6) for photodynamic therapy and fluorescence imaging. The in vitro results demonstrated that the as-synthesized nanoprobes could be efficiently internalized into A549 cells and then significantly enhance the mortality of cancer cells compared with free Ce6 and doxorubicin. For in vivo tests, the nanoprobes showed excellent tumor targeting ability, long blood circulation time, and could remarkably inhibit the growth of tumor. Our results will help to advance the design of combination strategies to enhance the efficacy of imaging-guided cancer therapy.

STATEMENT OF SIGNIFICANCE

The as-prepared CDGM NPs could accumulate into the tumor tissue with the enhanced permeability and retention (EPR) effect as well as the active tumor targeting ability from the MMP2 polypeptides. With the acid-sensitive linker, the doxorubicin (DOX) would be released from the synthesized nanoparticles after exposing to the acid tumor microenvironment. The CDGM NPs exhibit excellent tumor targeting ability and could remarkably suppress the growth of tumor compared with free Ce6 and DOX.

Enhanced Antitumor Effects of Epidermal Growth Factor Receptor Targetable Cetuximab-Conjugated Polymeric Micelles for Photodynamic Therapy

Nanocarrier-based delivery systems are promising strategies for enhanced therapeutic efficacy and safety of toxic drugs. Photodynamic therapy (PDT)—a light-triggered chemical reaction that generates localized tissue damage for disease treatments—usually has side effects, and thus patients receiving photosensitizers should be kept away from direct light to avoid skin phototoxicity. In this study, a clinically therapeutic antibody cetuximab (C225) was conjugated to the surface of methoxy poly(ethylene glycol)-b-poly(lactide) (mPEG-b-PLA) micelles via thiol-maleimide coupling to allow tumor-targetable chlorin e6 (Ce6) delivery. Our results demonstrate that more C225-conjugated Ce6-loaded polymeric micelles (C225-Ce6/PM) were selectively taken up than Ce6/PM or IgG conjugated Ce6/PM by epidermal growth factor receptor (EGFR)-overexpressing A431 cells observed by confocal laser scanning microscopy (CLSM), thereby decreasing the IC₅₀ value of Ce6-mediated PDT from 0.42 to 0.173 μM. No significant differences were observed in cellular uptake study or IC₅₀ value between C225-Ce6/PM and Ce6/PM groups in lower EGFR expression HT-29 cells. For antitumor study, the tumor volumes in the C225-Ce6/PM-PDT group (percentage of tumor growth inhibition, TGI% = 84.8) were significantly smaller than those in the Ce6-PDT (TGI% = 38.4) and Ce6/PM-PDT groups (TGI% = 53.3) (p < 0.05) at day 21 through reduced cell proliferation in A431 xenografted mice. These results indicated that active EGFR targeting of photosensitizer-loaded micelles provides a possible way to resolve the dose-limiting toxicity of conventional photosensitizers and represents a potential delivery system for PDT in a clinical setting.

Photosensitization mechanism of Cu(ii) porphyrins

This work presents the mechanism of the photoinduced generation of reactive oxygen species (ROS) by paramagnetic copper porphyrins in aqueous solution. Electronic structure calculations within the framework of the (time-dependent) density functional theory, (TD)DFT, reveal the details regarding the development of the atomistic and electronic structures of the copper porphyrin in solution along the set of chemical reactions accessible upon photoactivation. This study identifies the key parameters controlling the feasibility of the various reaction pathways that drive the formation of specific reactive oxygen species, ROS, i.e. superoxide, peroxyl and hydroxyl radicals. An important outcome of our results is the rationalization of how the water solvent molecules play a crucial role in most steps of the overall reaction. The present study is illustrated by focusing on one specific copper porphyrin for which precise experimental data have recently been measured, and can readily be generalized to the whole family of paramagnetic porphyrins. The conclusions of this work shed light on the rational design of metalloporphyrins as photosensitizers for photodynamic therapy.

pH-Responsive spherical nucleic acid for intracellular lysosome imaging and an effective drug delivery system

This study presents a class of pH-responsive spherical nucleic acids that can exactly image intracellular lysosomes and be an effective drug delivery system.

The synthesis of core–shell Cu9S5@mSiO2–ICG@PEG–LA for photothermal and photodynamic therapy

A Cu₉S₅@mSiO₂–ICG@PEG–LA core–shell nanocomposite was synthesized to integrate NIR-modulated PTT and PDT, revealing enhanced cytotoxicity to the HepG2 cell.

Doxorubicin/Ce6-Loaded Nanoparticle Coated with Polymer via Singlet Oxygen-Sensitive Linker for Photodynamically Assisted Chemotherapy

It is widely known that the therapeutic effect of nanoparticle-based chemotherapeutics could be greatly enhanced by the introduction of the photodynamic effect. Herein we report a chlorin e6-incorporated mesoporous silica nanoparticles (MSNs) covered with a polyethylene glycol shell conjugated via a singlet oxygen-sensitive labile bis(alkylthio)alkene linker (CeAP-L-PEG). In this study, single irradiation with biocompatible red light induced both intracellular doxorubicin release and photochemical internalization, and consequently enhanced anti-cancer effect was observed in vitro and in vivo. This study suggests the potential of our precisely designed nanoparticle system for photodynamically assisted chemotherapy.