CdSe/ZnS quantum dots induce photodynamic effects and cytotoxicity in pancreatic cancer cells

Photodynamic Therapy Using RGD-Functionalized Quantum Dots Elicit a Potent Immune Response in a Syngeneic Mouse Model of Pancreatic Cancer

Purpose

Photodynamic therapy (PDT) induces anti-tumor immune responses by triggering immunogenic cell death in tumor cells. Previously, we demonstrated that novel QDs-RGD nanoparticles exhibited high efficiency as photosensitizers in the treatment of pancreatic cancer. However, the underlying mechanism of the anti-tumor immune effects induced by the photosensitizer remains unknown. This study assessed the anticancer immune effect of QDs-RGD, as well as the conventional photosensitizer chlorine derivative, YLG-1, for comparison, against pancreatic cancer in support of superior therapeutic efficacy.

Methods

The pancreatic cancer cell line, Panc02, was used for in vitro studies. C57BL/6 mice bearing pancreatic cancer cell-derived xenografts were generated for in vivo studies to assess the anti-tumor effects of QDs-RGD-PDT and YLG-1-PDT. The immunostimulatory ability of both photosensitizers was examined by measuring the expression of damage-associated molecular patterns (DAMP), such as calreticulin (CRT), assessing dendritic cell (DC) maturation, and analyzing cytokine expression. The specific immunity of QDs-RGD and YLG-1-PDT on distant tumor were determined by combining PDT with anti-CTLA-4 antibody.

Results

QDs-RGD-PDT and YLG-1-PDT significantly inhibited pancreatic cancer cell growth in a dose- and time-dependent manner. While both photosensitizers significantly promoted CRT release, DC maturation, and interferon γ (IFN-γ) and tumor necrosis factor α (TNF-α) expression, QDs-RGD exerted a stronger immunostimulatory effect than YLG-1. Combination treatment with QDs-RGD and CTLA-4 blockade was able to significantly inhibit the growth of distant tumors.

Conclusion

QDs-RGD is a novel and effective PDT strategy for treating pancreatic tumors by inducing anti-tumor immune responses.

Trace elements in pancreatic cancer

BACKGROUND

Pancreatic cancer (PCA) is an extremely aggressive malignant cancer with an increasing incidence and a low five-year survival rate. The main reason for this high mortality is that most patients are diagnosed with PCA at an advanced stage, missing early treatment options and opportunities. As important nutrients of the human body, trace elements play an important role in maintaining normal physiological functions. Moreover, trace elements are closely related to many diseases, including PCA.

REVIEW

This review systematically summarizes the latest research progress on selenium, copper, arsenic, and manganese in PCA, elucidates their application in PCA, and provides a new reference for the prevention, diagnosis and treatment of PCA.

CONCLUSION

Trace elements such as selenium, copper, arsenic and manganese are playing an important role in the risk, pathogenesis, diagnosis and treatment of PCA. Meanwhile, they have a certain inhibitory effect on PCA, the mechanism mainly includes: promoting ferroptosis, inducing apoptosis, inhibiting metastasis, and inhibiting excessive proliferation.

Quantum Dots as a Potential Multifunctional Material for the Enhancement of Clinical Diagnosis Strategies and Cancer Treatments

Quantum dots (QDs) represent a class of nanoscale wide bandgap semiconductors, and are primarily composed of metals, lipids, or polymers. Their unique electronic and optical properties, which stem from their wide bandgap characteristics, offer significant advantages for early cancer detection and treatment. Metal QDs have already demonstrated therapeutic potential in early tumor imaging and therapy. However, biological toxicity has led to the development of various non-functionalized QDs, such as carbon QDs (CQDs), graphene QDs (GQDs), black phosphorus QDs (BPQDs) and perovskite quantum dots (PQDs). To meet the diverse needs of clinical cancer treatment, functionalized QDs with an array of modifications (lipid, protein, organic, and inorganic) have been further developed. These advancements combine the unique material properties of QDs with the targeted capabilities of biological therapy to effectively kill tumors through photodynamic therapy, chemotherapy, immunotherapy, and other means. In addition to tumor-specific therapy, the fluorescence quantum yield of QDs has gradually increased with technological progress, enabling their significant application in both in vivo and in vitro imaging. This review delves into the role of QDs in the development and improvement of clinical cancer treatments, emphasizing their wide bandgap semiconductor properties.

The bioengineered and multifunctional nanoparticles in pancreatic cancer therapy: Bioresponisive nanostructures, phototherapy and targeted drug delivery

The multidisciplinary approaches in treatment of cancer appear to be essential in term of bringing benefits of several disciplines and their coordination in tumor elimination. Because of the biological and malignant features of cancer cells, they have ability of developing resistance to conventional therapies such as chemo- and radio-therapy. Pancreatic cancer (PC) is a malignant disease of gastrointestinal tract in which chemotherapy and radiotherapy are main tools in its treatment, and recently, nanocarriers have been emerged as promising structures in its therapy. The bioresponsive nanocarriers are able to respond to pH and redox, among others, in targeted delivery of cargo for specific treatment of PC. The loading drugs on the nanoparticles that can be synthetic or natural compounds, can help in more reduction in progression of PC through enhancing their intracellular accumulation in cancer cells. The encapsulation of genes in the nanoparticles can protect against degradation and promotes intracellular accumulation in tumor suppression. A new kind of therapy for cancer is phototherapy in which nanoparticles can stimulate both photothermal therapy and photodynamic therapy through hyperthermia and ROS overgeneration to trigger cell death in PC. Therefore, synergistic therapy of phototherapy with chemotherapy is performed in accelerating tumor suppression. One of the important functions of nanotechnology is selective targeting of PC cells in reducing side effects on normal cells. The nanostructures are capable of being surface functionalized with aptamers, proteins and antibodies to specifically target PC cells in suppressing their progression. Therefore, a specific therapy for PC is provided and future implications for diagnosis of PC is suggested.

Hybrid Nanomat: Copolymer Template CdSe Quantum Dots In Situ Stabilized and Immobilized within Nanofiber Matrix

Fabrication and characterization of hybrid nanomats containing quantum dots can play a prominent role in the development of advanced biosensors and bio-based semiconductors. Owing to their size-dependent properties and controlled nanostructures, quantum dots (QDs) exhibit distinct optical and electronic characteristics. However, QDs include heavy metals and often require stabilizing agents which are toxic for biological applications. Here, to mitigate the use of toxic ligands, cadmium selenide quantum dots (CdSe QDs) were synthesized in situ with polyvinylpyrrolidone (PVP) at room temperature. The addition of PVP polymer provided size regulation, stability, and control over size distribution of CdSe QDs. The characterization of the optical properties of the CdSe QDs was performed using fluorescence and ultraviolet-visible (UV-Vis) spectroscopy. CdSe QDs exhibited a typical absorbance peak at 280 nm and a photoluminescence emission peak at 580 nm. Transmission electron microscopy (TEM) micrographs demonstrated that CdSe QDs having an average size of 6 ± 4 nm were obtained via wet chemistry method. CdSe QDs were immobilized in a blend of PVP and poly(L-lactide-co-ε-caprolactone) (PL-b-CL) copolymer that was electrospun to produce nanofibers. Scanning electron microscopy (SEM), thermal analyses and attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) were used to characterize properties of fabricated nanofibers. Both pristine and hybrid nanofibers possessed cylindrical geometry and rough surface features, facilitating increased surface area. Infrared absorption spectra showed a slight shift in absorbance peaks due to interaction of PVP-coated CdSe QDs and nanofiber matrix. The presence of CdSe QDs influenced the fiber diameter and their thermal stability. Further, in vitro biological analyses of hybrid nanofibers showed promising antibacterial effect and decline in cancer cell viability. This study offers a simple approach to obtain hybrid nanomats immobilized with size-controlled PVP-coated CdSe QDs, which have potential applications as biosensors and antibacterial and anticancer cell agents.

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.

Semiconductor quantum dots for photodynamic therapy: Recent advances

Photodynamic therapy is a promising cancer treatment that induces apoptosis as a result of the interactions between light and a photosensitizing drug. Lately, the emergence of biocompatible nanoparticles has revolutionized the prospects of photodynamic therapy (PDT) in clinical trials. Consequently, a lot of research is now being focused on developing non-toxic, biocompatible nanoparticle-based photosensitizers for effective cancer treatments using PDT. In this regard, semiconducting quantum dots have shown encouraging results. Quantum dots are artificial semiconducting nanocrystals with distinct chemical and physical properties. Their optical properties can be fine-tuned by varying their size, which usually ranges from 1 to 10 nm. They present many advantages over conventional photosensitizers, mainly their emission properties can be manipulated within the near IR region as opposed to the visible region by the former. Consequently, low intensity light can be used to penetrate deeper tissues owing to low scattering in the near IR region. Recently, successful reports on imaging and PDT of cancer using carbon (carbon, graphene based) and metallic (Cd based) based quantum dots are promising. This review aims to summarize the development and the status quo of quantum dots for cancer treatment.

Photodynamic Therapeutic Effect of Nanostructured Metal Sulfide Photosensitizers on Cancer Treatment

Photodynamic therapy (PDT) utilizes photosensitizers (PSs) to produce reactive oxygen species (ROSs) upon irradiation, which causes the shutdown of vessels and deprives the tumor of nutrients and oxygen, and in turn induces adverse effects on the immune system. However, significant efforts are needed to increase the efficiency in PDT in terms of light delivery to specific PSs for the clinical treatment of tumors located deep under the skin. Even though PDT offers a disease site-specific treatment modality, current efforts are directed to improve the solubility (in body fluids and injectable solvents), photostability, amphiphilicity (for tissue penetration), elimination, and systemic toxicity of traditional PSs based on porphyrin derivatives. Nanostructured materials show promising features to achieve most of such combined efforts. They can be artificially engineered to carry multiple theranostic agents onto targeted tumor sites. However, recent studies on photosensitive Cd-based nanostructures, mostly used in PDT, indicate that leeching of Cd2+ ions is stimulated when they are exposed to harsh biological conditions for continuous periods of time, thus making them acutely toxic and hindering their applications in in vivo settings. Since nanostructured materials are not completely immune to degradation, great strides have been made to seek new alternatives. In this review, we focus on the latest advances of Cd-free nanostructured metal transition sulfides (MTSs) as alternative PSs and study their high-energy transfer efficiency, rational designs, and potential applications in cancer-targeted PDT. Nanostructured MTSs are discussed in the context of their versatility to serve as phototherapy agents and superior properties, including their strong absorption in the NIR region, excellent photothermal conversion efficiency, controlled reactive oxygen species (ROS) production, versatile surface chemistry, high fluorescence, and structural and thermal stability. We discuss the latest advancements in correlating the self-aggregation of MTSs with their passive tumor cell targeting, highlighting their ability to efficiently produce ROSs, and mitigating their dark toxicity through polymeric functionalization. Treatment of deep-seated tumors by using these PSs upon preferential uptake by tumor tissues (due to the enhanced permeability and retention effect) is also reviewed. We finally summarize the main future perspectives of MTSs as next-generation PSs within the context of cancer theranostics.

Multifunctional MnCuInSe/ZnS quantum dots for bioimaging and photodynamic therapy

In this work, manganese (Mn)-doped CuInSe quantum dots (QDs) with a ZnS passivation layer (MnCuInSe/ZnS) have been synthesized via a one-pot microwave-assisted hydrothermal reaction using glutathione (GSH) as a stabilizer. The MnCuInSe/ZnS core-shell QDs combine magnetic resonance imaging (MRI), excitation-dependent red emission, and reactive oxygen radical generation functions, in which regulation of Mn2+ incorporation leads to synergistic imaging and therapeutic modalities. The MnCuInSe/ZnS QDs exhibit high colloidal and photochemical stability in simulated media and at different pH values. An r2/r1 ratio of 9.99 was calculated from MRI studies suggesting their potential application as dual-modal imaging agents. Based on in vitro tests on Hela, B16, and HepG2 cell lines, it is apparent that MnCuInSe/ZnS QDs impose no significant cytotoxicity in the dark, while they can efficiently generate singlet oxygen radicals for photodynamic therapy of cancers, killing more than 80% of B16 cells within 5 min of laser irradiation (671 nm, 1 W cm−2). Furthermore, in vitro fluorescence imaging and cellular internalization of QDs are examined to visualize cellular uptake and in situ ROS generation. Therefore, this research exemplifies a new set of multifunctional chalcogenide QDs for theranostic applications.

Melittin-Based Nano-Delivery Systems for Cancer Therapy

Melittin (MEL) is a 26-amino acid polypeptide with a variety of pharmacological and toxicological effects, which include strong surface activity on cell lipid membranes, hemolytic activity, and potential anti-tumor properties. However, the clinical application of melittin is restricted due to its severe hemolytic activity. Different nanocarrier systems have been developed to achieve stable loading, side effects shielding, and tumor-targeted delivery, such as liposomes, cationic polymers, lipodisks, etc. In addition, MEL can be modified on nano drugs as a non-selective cytolytic peptide to enhance cellular uptake and endosomal/lysosomal escape. In this review, we discuss recent advances in MEL’s nano-delivery systems and MEL-modified nano drug carriers for cancer therapy.

Fate of CdSe/ZnS quantum dots in cells: Endocytosis, translocation and exocytosis

Semiconductor quantum dots (QDs) have been extensively explored for extensive bioapplications, yet their cellular fate, especially exocytosis, has not been thoroughly investigated. Herein, we systematically investigated the whole cellular process from the endocytosis, intercellular trafficking, to the exocytosis of a typical QD, core/shell CdSe/ZnS QD. Using confocal laser scanning microscopy and flow cytometry, and after carefully eliminating the effect of cell division, we found that the QDs were internalized by HeLa cells with a time-, dose-, and serum-dependent manner. The cellular uptake was inhibited by serum, but eventually peaked after 4-6 h incubation with or without serum. The primary endocytosis pathway was clathrin-mediated, and actin- and microtubule-dependent in the medium with serum, while the caveolae-mediated endocytosis and macropinocytosis were more important for the QDs in the serum-free medium. Inside cells, most QDs distributed in lysosomes, and some entered mitochondria, endoplasmic reticulum, and Golgi apparatus. The translocation of the QDs from other organelles to Golgi apparatus was observed. The exocytosis of QDs was faster than the endocytosis, reaching the maximum in about one hour after cultured in fresh culture medium, with around 60% of the internalized QDs remained undischarged. The exocytosis process was energy- and actin-dependent, and the lysosome exocytosis and endoplasmic reticulum/Golgi pathway were the main routes. This study provides a full picture of behavior and fate of QDs in cells, which may facilitate the design of ideal QDs applied in biomedical and other fields.

CdSe/ZnS quantum dots exhibited nephrotoxicity through mediating oxidative damage and inflammatory response

Objective: This study aimed to the evaluate the nephrotoxicity of CdSe/ZnS QDs in vitro and vivo, as well as investigate the underlying toxicity mechanisms.

Results: In vitro experiments showed that compared with control cells, CdSe/ZnS QDs treatment significantly inhibited cell viability and promoted cell apoptosis in dose-dependent manner in NRK cells. Notably, CdSe/ZnS QDs treatment increased the contents of MDA and ROS, and decreased the activities of SOD, CAT and GSH-Px; however, the co-treatment of NAC and QDs relieved the oxidative damage of NRK cells. Moreover, in vivo experiments also revealed that CdSe/ZnS QDs treatment obviously increased kidney weight coefficient, damaged the kidney function, as well as induced inflammatory response and inhibited the activation of NRF2/Keap1 pathway in kidney tissues of mice.

Conclusions: CdSe/ZnS QDs exhibited obvious nephrotoxicity by mediating oxidative damage and inflammatory response in vitro and in vivo via NRF2/Keap1 pathway.

Methods: The characterization of CdSe/ZnS QDs was analyzed by transmission electron microscope, emission spectrum scanning, and dynamic light scattering. Rat kidney cells (NRK) were exposed to different doses of CdSe/ZnS QDs with or without N-acetylcysteine (NAC, antioxidant). Then, cellular uptake of CdSe/ZnS QDs was detected, and in vitro cytotoxicity was evaluated by MTT assay and TUNEL assay.

The Future of Anticancer Drugs: A Cytotoxicity Assessment Study of CdSe/ZnS Quantum Dots

Quantum dots (QDs), including CdSe/ZnS, are nanoparticles emitting various wavelengths of fluorescent light depending on their size. Fluorescence allows them to be exploited for in vivo sensing/imaging of cancer cells. Nevertheless, thorough assessments of the effects of these commonly used QDs on cell stability are essentially required prior to their full applications. To investigate the effects of Cd QDs on the growth of human cervical cancer cells (HeLa), we utilized a growth assay, a reactive oxygen species (ROS) assay, an apoptosis assay, and RNA-seq. The growth assay results showed significant proliferation inhibition of HeLa cells by CdSe/ZnS. We revealed that smaller green CdSe/ZnS exerts more toxic effects than slightly larger yellow CdSe/ZnS. There were no significant increases of ROSs under the treatment of Cd QDs, which is consistent with the notion that low concentration of Cd QDs does not cause significant production of ROSs. In addition, we found that Cd QDs induced late apoptosis. RNA-Seq-based transcriptome analysis revealed that the exposure to green Cd QDs significantly upregulated antiapoptotic, antiproliferative, and antitumorigenic functions. The transcriptome profile also noted the downregulation of pro-proliferation, mitochondrial respiratory chain, detoxification, and receptor-mediated endocytosis. Taken together, our findings provide evidence that green CdSe/ZnS can be an alternative anticancer drug. In addition, our transcriptome analysis provides new insights into alteration of physiological state induced by CdSe/ZnS QDs in HeLa cancer cells.

Photodynamic therapy of pancreatic cancer: Where have we come from and where are we going?

Photodynamic therapy (PDT) is a potential adjuvant therapy in pancreatic cancer with several advantages. Mechanistically, pancreatic cancer PDT can induce apoptosis and necrosis of pancreatic cancer cells and lead to vascular damage and enhance anti-tumor immune response in tumor tissues. However, limitations of current photosensitizers such as limited penetration depth, poor targeted therapy and inadequate reactive oxygen species (ROS) generation still exist. Recently, several novel photosensitizers have been reported to break through limits in pancreatic cancer PDT. Methods combined with biomedical engineering, materialogy and chemical engineering have been employed to overcome the difficulties and to realize targeted therapy. Preclinical and clinical trials also preliminarily confirmed the technical feasibility and safety of pancreatic cancer PDT. Therefore, PDT may be potential to be used as an effective adjuvant therapy in pancreatic cancer multimodality therapy. This review will give an overview about pancreatic cancer PDT from basic experimental studies, preclinical and clinical application to future direction of pancreatic cancer PDT.

The hurdles of nanotoxicity in transplant nanomedicine

Nanomedicine has matured significantly in the past 20 years and a number of nanoformulated therapies are cleared by regulatory agencies for use across the globe. Transplant medicine is one area that has significantly benefited from the advancement of nanomedicine in recent times. However, while nanoparticle-based therapies have improved toxicological profiles of some drugs, there are still a number of aspects regarding the biocompatibility and toxicity of nanotherapies that require further research. The goal of this article is to review toxicological profiles of immunosuppressant therapies and their conversion into nanomedicine formulations as well as introduce future challenges associated with current in vitro and in vivo toxicological models.

Recent advances in photodynamic therapy for cancer and infectious diseases

Photodynamic therapy (PDT) is a treatment by combining light and a photosensitizer to generate reactive oxygen species (ROS) for cellular damage, and is used to treat cancer and infectious diseases. In this review, we focus on recent advances in design of new photosensitizers for increased production of ROS and in genetic engineering of biological photosensitizers to study cellular signaling pathways. A new concept has been proposed that PDT-induced acute inflammation can mediate neutrophil infiltration to deliver therapeutics in deep tumor tissues. Combination of PDT and immunotherapies (neutrophil-mediated therapeutic delivery) has shown the promising translation of PDT for cancer therapies. Furthermore, a new area in PDT is to treat bacterial infections to overcome the antimicrobial resistance. Finally, we have discussed the new directions of PDT for therapies of cancer and infectious diseases. In summary, we believe that rational design and innovations in nanomaterials may have a great impact on translation of PDT in cancer and infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Recent advances in photodynamic therapy for cancer and infectious diseases

Photodynamic therapy (PDT) is a treatment by combining light and a photosensitizer to generate reactive oxygen species (ROS) for cellular damage, and is used to treat cancer and infectious diseases. In this review, we focus on recent advances in design of new photosensitizers for increased production of ROS and in genetic engineering of biological photosensitizers to study cellular signaling pathways. A new concept has been proposed that PDT-induced acute inflammation can mediate neutrophil infiltration to deliver therapeutics in deep tumor tissues. Combination of PDT and immunotherapies (neutrophil-mediated therapeutic delivery) has shown the promising translation of PDT for cancer therapies. Furthermore, a new area in PDT is to treat bacterial infections to overcome the antimicrobial resistance. Finally, we have discussed the new directions of PDT for therapies of cancer and infectious diseases. In summary, we believe that rational design and innovations in nanomaterials may have a great impact on translation of PDT in cancer and infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Poly(Lactide-Co-Glycolide) Nanoparticles Co-Loaded with Chlorophyllin and Quantum Dots as Photodynamic Therapy Agents

Photodynamic therapy (PDT) is an approach to treating cancer and involves light-induced activation of a photosensitizer that triggers the formation of reactive oxygen species (ROS) in targeted cells and subsequent cell death. Examples of photosensitizers are porphyrins, including the natural compound chlorophyll. These molecules can be delivered alone or co-formulated with an agent, such as quantum dots (QDs), that is able to excite them through a fluorescence resonance energy transfer (FRET)-based mechanism. We encapsulated a chlorophyllin copper complex and CdSe/ZnS core-shell QDs into biodegradable nanoparticles (NPs) composed of poly(lactide-co-glycolide) (PLGA), that allow modification with specific targeting ligands. When excited at 365 nm, FRET occurs between co-encapsulated QDs and chlorophyllin to result in the formation of ROS. This chlorophyllin-QD coformulation allows generation of ROS both in an aqueous environment and in cells, thus confirming the potential of this formulation in PDT.

Biodistribution and toxicity assessment of intratumorally injected arginine-glycine-aspartic acid peptide conjugated to CdSe/ZnS quantum dots in mice bearing pancreatic neoplasm

Quantum dots (QDs) conjugated with arginine-glycine-aspartic acid (RGD) peptides (which are integrin antagonists) are novel nanomaterials with the unique optical property of high molar extinction coefficient, and they have potential utility as photosensitizers in photodynamic therapy (PDT). Our group previously demonstrated significant benefits of using PDT with QD-RGD on pancreatic tumor cells. This study aimed to evaluate the biodistribution and toxicity of QD-RGD in mice prior to in vivo application. Mice with pancreatic neoplasms were intratumorally injected with varying doses of QD-RGD, and the biodistribution 0-24 h post injection was compared to that in control mice (intravenously injected with unconjugated QD). Various tissue samples were collected for toxicity analyses, which included inductively coupled plasma mass spectrometry (ICP-MS) to assess Cd²⁺ concentrations and hematoxylin-eosin staining for histopathological examination. Fluorescent imaging revealed relatively sufficient radiant efficiency in mice under specific conditions. The ICP-MS and HE data showed no significant signs of necrosis due to Cd²⁺ release by QDs. The mice survived well and had no apparent weakness or weight loss during the 4 weeks post injection. These findings provide novel insights into the biodistribution of QD-RGD and encourage profound in vivo studies regardless of safety concerns. These findings alleviate safety concerns and provide novel insights into the biodistribution of QD-RGD, offering a solid foundation for comprehensive in vivo studies.

Intracellular ROS levels determine the apoptotic potential of keratinocyte by Quantum Dot via blockade of AKT Phosphorylation

Quantum dots (QDs) have shown great potential for biomedical use in a broad range including diagnostic agents. However, the regulatory mechanism of dermal toxicity is poorly understood. In this study, we investigated how QDs-induced apoptosis is regulated in human keratinocytes. We also examined the effect of carboxylic acid-coated QDs (QD 565 and QD 655) on reactive oxygen species (ROS) production and apoptosis-related cellular signalling. The viability of keratinocyte was inhibited by two types of QDs in a concentration-dependent manner. QDs induce ROS production and blockade of AKT phosphorylation. Moreover, the cleavage of AKT-dependent pro-apoptotic proteins such as poly (ADP-ribose) polymerase, caspases-3 and caspases-9 was significantly increased. We also found that a decrease in cellular ROS level by ROS scavenger, N-acetylcysteine (NAC), resulting in the abolishment of QDs-induced AKT de-phosphorylation and cellular apoptosis. Interestingly, QD 655 had a more cytotoxic effect including oxidative stress and AKT-dependent apoptosis than QD 565. In addition, QD 655 had the cytotoxic potential in the human skin equivalent model (HSEM). These data show that QD-induced intracellular ROS levels may be an important parameter in QD-induced apoptosis. These findings from this study indicate that intracellular ROS levels might determine the apoptotic potential of keratinocyte by QD via blockade of AKT phosphorylation.

Effects of arginine-glycine-aspartic acid peptide-conjugated quantum dots-induced photodynamic therapy on pancreatic carcinoma in vivo

Quantum dots (QDs) conjugated with integrin antagonist arginine-glycine-aspartic acid (RGD) peptides (QDs-RGD) are novel nanomaterials with a unique optical property: a high molar extinction coefficient. Previously, we have shown that QDs-RGD demonstrate a photodynamic therapy (PDT) effect as new photosensitizers for the pancreatic cancer cell line SW1990 in vitro. Here, we investigate the application of QDs-RGD in mice bearing pancreatic tumors using PDT. To ensure that more photosensitizers accumulated in tumors, QDs-RGD were injected intratumorally. After selection of an adequate dosage for injection from analyses of biodistribution images captured by an IVIS system, PDT was initiated. Three groups were created according to different PDT procedures. In group 1, mice were injected with QDs-RGD intratumorally, and an optical fiber connected to a laser light was inserted directly into the tumor. Irradiation was sustained for 20 min with a laser light (630 nm) at 100 mW/cm2. In group 2, the laser optical fiber was placed around, and not inserted into, tumors. In group 3, PDT was conducted as in group 1 but without injection of QDs-RGD. After 28 days of observation, tumors on the back of mice in group 1 grew slowly (V/V0 =3.24±0.70) compared with the control groups, whose tumors grew quickly, and the mean V/V0 reached 6.08±0.50 (group 2) and 7.25±0.82 (group 3). Histology of tumor tissues showed more necrotic tissues, more inflammatory cells, and less vascular tissue in the PDT group than those in the control groups. These results suggest that QDs-RGD-mediated PDT, with illumination using an optical fiber inserted directly into the tumor, can inhibit the growth of SW1990 tumors with high efficiency in nude mice.