pH-Dependent Transmembrane Activity of Peptide-Functionalized Gold Nanostars for Computed Tomography/Photoacoustic Imaging and Photothermal Therapy

The theranostic efficiency of tumor-specific, pH-responsive, peptide-modified, liposome-containing paclitaxel and superparamagnetic iron oxide nanoparticles

Background

In the present study, the tumor-specific, pH-responsive peptide H₇K(R₂)₂-modified, theranostic liposome-containing paclitaxel (PTX) and superparamagnetic iron oxide nanoparticles (SPIO NPs), PTX/SPIO-SSL-H₇K(R₂)₂, was prepared by using H₇K(R₂)₂ as the targeting ligand, SPIO NPs as the magnetic resonance imaging (MRI) agent, PTX as antitumor drug.

Methods

The PTX/SPIO-SSL-H₇K(R₂)₂ was prepared by a thin film hydration method. The characteristics of PTX/SPIO-SSL-H₇K(R₂)₂ were evaluated. The targeting effect, MRI, and antitumor activity of PTX/SPIO-SSL-H₇K(R₂)₂ were investigated detail in vitro and in vivo in human breast carcinoma MDA-MB-231 cell models.

Results

Our results of in vitro flow cytometry, in vivo imaging, and in vivo MR imaging confirmed the pH-responsive characteristic of H₇K(R₂)₂ in MDA-MB-231 cell line in vitro and in vivo. The results of in vivo MRI and in vivo antitumor activity confirmed the theranostic effect of PTX/SPIO-SSL-H₇K(R₂)₂ in MDA-MB-231 tumor-bearing model.

Conclusion

Considering all our in vitro and in vivo results, we conclude that we developed targeting modified theranostic liposome which could achieve both role of antitumor and MRI.

In Vivo Computed Tomography/Photoacoustic Imaging and NIR-Triggered Chemo-Photothermal Combined Therapy Based on a Gold Nanostar-, Mesoporous Silica-, and Thermosensitive Liposome-Composited Nanoprobe

Safe multifunctional nanoplatforms that have multiple therapeutic functions integrated with imaging capabilities are highly desired for biomedical applications. In this paper, targeted chemo-photothermal synergistic therapy and photoacoustic/computed tomography imaging of tumors were achieved by one novel multifunctional nanoprobe (GMS/DOX@SLB-FA); it was composed of a gold nanostar core and a doxorubicin (DOX)-loaded mesoporous silica shell (GMS), which was coated with a folic acid (FA)-modified thermosensitively supported lipid bilayer (SLB-FA) as a gatekeeper. The multifunctional probe had perfect dispersion and stability; 2.1 nm mesoporous pores and 208 nm hydration particle sizes were obtained. In vitro studies indicated that the drug-loaded probe had excellent ability to control the release of DOX, with 71.98 ± 2.52% cumulative release after laser irradiation, which was significantly higher than that of unirradiated control group. A survival rate of 72.75 ± 4.37% of HeLa cells at 57.75 μg/mL probe also demonstrated the low cytotoxicity of the targeted probe. Both in vitro and in vivo results showed that the probe could achieve targeted photoacoustic imaging of tumors because of the fact that the FA-modified probe could specifically recognize the overexpressed FA receptors on tumor cells; meanwhile, the probe could also achieve the chemo-photothermal synergistic therapy of tumors through controlling the drug release from mesoporous channels by a near-infrared laser. Therefore, the probe had great potential in the early diagnosis and treatment of cancer.

Strategies in the design of gold nanoparticles for intracellular targeting: opportunities and challenges

With unique physicochemical properties, gold nanoparticles (Au NPs) have demonstrated their potential as drug carriers or therapeutic agents. Effective guidance of Au NPs into specific intracellular destinations becomes increasingly important as we strive to further improve the efficiency of drug delivery and modulate controllable cellular responses. In this review, we summarized recent advances in designing Au NPs with the capabilities of cellular penetration and internalization, endosomal escape, intracellular trafficking and subcellular localization via various approaches including physical injection, tuning the physiochemical parameters of Au NPs, and surface modification with targeting ligands. Strategies for delivering Au NPs to specific subcellular destinations including the nucleus, mitochondria, endoplasmic reticulum, lysosomes are also discussed. Moreover, current challenges associated with intracellular targeting of Au NPs are discussed with future perspectives proposed.

pH-sensitive pHLIP® coated niosomes

Nanomedicine is becoming very popular over conventional methods due to the ability to tune physico-chemical properties of nano vectors, which are used for encapsulation of therapeutic and diagnostic agents. However, the success of nanomedicine primarily relies on how specifically and efficiently nanocarriers can target pathological sites to minimize undesirable side effects and enhance therapeutic efficacy. Here, we introduce a novel class of targeted nano drug delivery system, which can be used as an effective nano-theranostic for cancer. We formulated pH-sensitive niosomes (80-90 nm in diameter) using nonionic surfactants Span20 (43-45 mol%), cholesterol (50 mol%) and 5 mol% of pH (Low) insertion peptide (pHLIP) conjugated with DSPE lipids (DSPE-pHLIP) or hydrophobic fluorescent dye, pyrene, (Pyr-pHLIP). In coating of niosomes, pHLIP was used as an acidity sensitive targeting moiety. We have demonstrated that pHLIP coated niosomes sense the extracellular acidity of cancerous cells. Intravenous injection of fluorescently labeled (R18) pHLIP-coated niosomes into mice bearing tumors showed significant accumulation in tumors with minimal targeting of kidney, liver and muscles. Tumor-targeting niosomes coated with pHLIP exhibited 2-3 times higher tumor uptake compared to the non-targeted niosomes coated with PEG polymer. Long circulation time and uniform bio-distribution throughout the entire tumor make pHLIP-coated niosomes to be an attractive novel delivery system.

Highly water-stable rare ternary Ag-Au-Se nanocomposites as long blood circulation time X-ray computed tomography contrast agents

X-ray computed tomography (CT) is a powerful and widely used medical non-invasive technique that often requires intravenous administration of contrast agents (CAs) to better visualize soft tissues. In this work, we have developed a novel CT contrast agent based on ternary Ag-Au-Se chalcogenide nanoparticles (NP). A facile ligand exchange by using a 3 kDa PEGylated ligand with a dithiol dihydrolipoic acid as an anchor group resulted in highly water-soluble and monodisperse nanoparticles. These PEGylated ternary NPs were tested in vivo in mice, showing slow uptake by the mononuclear phagocyte system, long blood circulation times, low toxicity, and very good X-ray contrast, thus being promising candidates as CT contrast agents for clinical applications.

Theranostic Probes for Targeting Tumor Microenvironment: An Overview

Long gone is the time when tumors were thought to be insular masses of cells, residing independently at specific sites in an organ. Now, researchers gradually realize that tumors interact with the extracellular matrix (ECM), blood vessels, connective tissues, and immune cells in their environment, which is now known as the tumor microenvironment (TME). It has been found that the interactions between tumors and their surrounds promote tumor growth, invasion, and metastasis. The dynamics and diversity of TME cause the tumors to be heterogeneous and thus pose a challenge for cancer diagnosis, drug design, and therapy. As TME is significant in enhancing tumor progression, it is vital to identify the different components in the TME such as tumor vasculature, ECM, stromal cells, and the lymphatic system. This review explores how these significant factors in the TME, supply tumors with the required growth factors and signaling molecules to proliferate, invade, and metastasize. We also examine the development of TME-targeted nanotheranostics over the recent years for cancer therapy, diagnosis, and anticancer drug delivery systems. This review further discusses the limitations and future perspective of nanoparticle based theranostics when used in combination with current imaging modalities like Optical Imaging, Magnetic Resonance Imaging (MRI) and Nuclear Imaging (Positron Emission Tomography (PET) and Single Photon Emission Computer Tomography (SPECT)).