Synthesis of Size-Tunable Hollow Polypyrrole Nanostructures and Their Assembly into Folate-Targeting and pH-Responsive Anticancer Drug-Delivery Agents

Development of a Specific Aptamer-Modified Nano-System to Treat Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a prevalent gastrointestinal cancer characterized by high mortality and an unfavorable prognosis. While combination therapies involving surgery, chemotherapy, and radiation therapy are advancing, targeted therapy for ESCC remains underdeveloped. As a result, the overall five-year survival rate for ESCC is still below 20%. Herein, ESCC-specific DNA aptamers and an innovative aptamer-modified nano-system is introduced for targeted drug and gene delivery to effectively inhibit ESCC. The EA1 ssDNA aptamer, which binds robustly to ESCC cells with high specificity and affinity, is identified using cell-based systematic evolution of ligands by exponential enrichment (cell-SELEX). An EA1-modified nano-system is developed using a natural egg yolk lipid nanovector (EA1-EYLNs-PTX/siEFNA1) that concurrently loads paclitaxel (PTX) and a small interfering RNA of Ephrin A1 (EFNA1). This combination counters ESCC's proliferation, migration, invasion, and lung metastasis. Notably, EFNA1 is overexpressed in ESCC tumors with lung metastasis and has an inverse correlation with ESCC patient prognosis. The EA1-EYLNs-PTX/siEFNA1 nano-system offers effective drug delivery and tumor targeting, resulting in significantly improved therapeutic efficacy against ESCC tumors. These insights suggest that aptamer-modified nano-systems can deliver drugs and genes with superior tumor-targeting, potentially revolutionizing targeted therapy in ESCC.

Delivery of Chemotherapy Agents and Nucleic Acids with pH-Dependent Nanoparticles

With less than one percent of systemically injected nanoparticles accumulating in tumors, several novel approaches have been spurred to direct and release the therapy in or near tumors. One such approach depends on the acidic pH of the extracellular matrix and endosomes of the tumor. With an average pH of 6.8, the extracellular tumor matrix provides a gradient for pH-responsive particles to accumulate, enabling greater specificity. Upon uptake by tumor cells, nanoparticles are further exposed to lower pHs, reaching a pH of 5 in late endosomes. Based on these two acidic environments in the tumor, various pH-dependent targeting strategies have been employed to release chemotherapy or the combination of chemotherapy and nucleic acids from macromolecules such as the keratin protein or polymeric nanoparticles. We will review these release strategies, including pH-sensitive linkages between the carrier and hydrophobic chemotherapy agent, the protonation and disruption of polymeric nanoparticles, an amalgam of these first two approaches, and the release of polymers shielding drug-loaded nanoparticles. While several pH-sensitive strategies have demonstrated marked antitumor efficacy in preclinical trials, many studies are early in their development with several obstacles that may limit their clinical use.

Controlled growth of titanium dioxide nanotubes for doxorubicin loading and studies of in vitro antitumor activity

Titanium dioxide (TiO₂) materials are suitable for use as drug carriers due to their natural biocompatibility and nontoxicity. The aim of the study presented in this paper was to investigate the controlled growth of TiO₂ nanotubes (TiO₂ NTs) of different sizes via an anodization method, in order to delineate whether the size of NTs governs their drug loading and release profile as well as their antitumor efficiency. TiO₂ NTs were tailored to sizes ranging from 25 nm to 200 nm according to the anodization voltage employed. The TiO₂ NTs obtained by this process were characterized using scanning electron microscopy, transmission electron microscopy, and dynamic light scattering The larger TiO₂ NTs exhibited greatly improved doxorubicin (DOX)-loading capacity (up to 37.5 wt%), which contributed to their outstanding cell-killing ability, as evidenced by their lower half-maximal inhibitory concentration (IC50). Comparisons were carried out of cellular uptake and intracellular release rates of DOX for large and small TiO₂ NTs loaded with DOX. The results showed that the larger TiO₂ NTs represent a promising therapeutic carrier for drug loading and controlled release, which could improve cancer treatment outcomes. Therefore, TiO₂ NTs of larger size are useful substances with drug-loading potency that may be used in a wide range of medical applications.

Polypyrrole Nanomaterials: Structure, Preparation and Application

In the past decade, nanostructured polypyrrole (PPy) has been widely studied because of its many specific properties, which have obvious advantages over bulk-structured PPy. This review outlines the main structures, preparation methods, physicochemical properties, potential applications, and future prospects of PPy nanomaterials. The preparation approaches include the soft micellar template method, hard physical template method and templateless method. Due to their excellent electrical conductivity, biocompatibility, environmental stability and reversible redox properties, PPy nanomaterials have potential applications in the fields of energy storage, biomedicine, sensors, adsorption and impurity removal, electromagnetic shielding, and corrosion resistant. Finally, the current difficulties and future opportunities in this research area are discussed.

Capsule-like molecular imprinted polymer nanoparticles for targeted and chemophotothermal synergistic cancer therapy

Selective cancer cell targeting, controlled drug release, easy construction and multiple therapeutic modalities are some of the desirable characteristics of drug delivery systems. We designed and built simple capsule-like molecular imprinted polymer (MIP)-based nanoparticles for targeted and chemo-photothermal synergistic cancer therapy. Using dopamine (DA) as functional monomer, cross-linking agent as well as photo-thermal agent, ZIF-8 (zeoliticimidazolate framework-8) as drug carrier, epitope of EGFR (epidermal growth factor receptor) as template molecules, molecular imprinted polymer (MIP) drug carrier was constructed. The ability of MIP layer to bind to EGFR epitope endowed the MD (DOX@MIP) particles to recognize EGFR-overexpressing cancer cells, while the pH-responsiveness and photothermal conversion ability of PDA (polydopamine) achieved chemo-photothermal synergistic effects upon NIR irradiation. Taken together, the MD nanoparticles integrated cancer cell targeting recognition, intelligent drug release, biocompatibility and chemo-photothermal effects, and is therefore a promising tool for targeted cancer therapy with minimal toxicity to normal cells, as well as tumor imaging.

TME-Responsive Multistage Nanoplatform for siRNA Delivery and Effective Cancer Therapy

Since the discovery of RNA interference (RNAi), RNAi technology has rapidly developed into an efficient tool for post-transcriptional gene silencing, which has been widely used for clinical or preclinical treatment of various diseases including cancer. Small interfering RNA (siRNA) is the effector molecule of RNAi technology. However, as polyanionic macromolecules, naked siRNAs have a short circulatory half-life (<15 min) and is rapidly cleared by renal filtration, which greatly hinders their clinical application. Furthermore, the anionic and macromolecular characteristics of naked siRNAs impede their readiness to cross the cell membrane and therefore delivery vehicles are required to facilitate the cellular uptake and cytosolic delivery of naked siRNAs. In the past decade, numerous nanoparticles (NPs) such as liposomes have been employed for in vivo siRNA delivery, which have achieved favorable therapeutic outcomes in clinical disease treatment. In particular, because tumor microenvironment (TME) or tumor cells show several distinguishing biological/endogenous factors (eg, pH, enzymes, redox, and hypoxia) compared to normal tissues or cells, much attention has recently paid to design and construct TME-responsive NPs for multistaged siRNA delivery, which can respond to biological stimuli to achieve efficient in vivo gene silencing and better anticancer effect. In this review, we summarize recent advances in TME-responsive siRNA delivery systems, especially multistage delivery NPs, and discuss their design principles, functions, effects, and prospects.

Nanoparticles as a Tool in Neuro-Oncology Theranostics

The rapid growth of nanotechnology and the development of novel nanomaterials with unique physicochemical characteristics provides potential for the utility of nanomaterials in theranostics, including neuroimaging, for identifying neurodegenerative changes or central nervous system malignancy. Here we present a systematic and thorough review of the current evidence pertaining to the imaging characteristics of various nanomaterials, their associated toxicity profiles, and mechanisms for enhancing tropism in an effort to demonstrate the utility of nanoparticles as an imaging tool in neuro-oncology. Particular attention is given to carbon-based and metal oxide nanoparticles and their theranostic utility in MRI, CT, photoacoustic imaging, PET imaging, fluorescent and NIR fluorescent imaging, and SPECT imaging.

Multistage-responsive clustered nanosystem to improve tumor accumulation and penetration for photothermal/enhanced radiation synergistic therapy

Developing new strategies to overcome biological barriers and achieve efficient delivery of therapeutic nanoparticles (NPs) is the key to achieve positive therapeutic outcomes in nanomedicine. Herein, a multistage-responsive clustered nanosystem is designed to systematically resolve the multiple tumor biological barriers conflict between the enhanced permeability retention (EPR) effect and spatially uniform penetration of the nanoparticles. The nanosystem with desirable diameter (initial size of ~50 nm), which is favorable for long blood circulation and high propensity of extravasation through tumor vascular interstices, can accumulate effectively around the tumor tissue through the EPR effect. Then, these pH-responsive nanoparticles are conglomerated to form large-sized aggregates (~1000 nm) in the tumor under the acidic microenvironment, and demonstrated great tumor retention. Subsequently, the photothermal treatment disperses the aggregates to be ultrasmall gold nanoclusters (~5 nm), thereby improving their tumor penetration ability, and enhancing the radiotherapeutic effect by radiosensitizer. In 4T1 tumor model, this nanosystem shows great tumor accumulation and penetration, and the tumor growth and the lung/liver metastasis in particle/PTT/RT treated mice is significantly inhibited. As a photoacoustic/fluorescence imaging agent and PT/RT synergistic agent, this pH-/laser-triggered size multistage-responsive nanosystem displayes both great tumor accumulation and penetration abilities, and shows excellent potential in tumor therapy.

Biomedical Applications of Multifunctional Polymeric Nanocarriers: A Review of Current Literature

Polymeric nanomaterials have become a prominent area of research in the field of drug delivery. Their application in nanomedicine can improve bioavailability, pharmacokinetics, and, therefore, the effectiveness of various therapeutics or contrast agents. There are many studies for developing new polymeric nanocarriers; however, their clinical application is somewhat limited. In this review, we present new complex and multifunctional polymeric nanocarriers as promising and innovative diagnostic or therapeutic systems. Their multifunctionality, resulting from the unique chemical and biological properties of the polymers used, ensures better delivery, and a controlled, sequential release of many different therapeutics to the diseased tissue. We present a brief introduction of the classical formulation techniques and describe examples of multifunctional nanocarriers, whose biological assessment has been carried out at least in vitro. Most of them, however, also underwent evaluation in vivo on animal models. Selected polymeric nanocarriers were grouped depending on their medical application: anti-cancer drug nanocarriers, nanomaterials delivering compounds for cancer immunotherapy or regenerative medicine, components of vaccines nanomaterials used for topical application, and lifestyle diseases, ie, diabetes.

β-Cyclodextrin coated and folic acid conjugated magnetic halloysite nanotubes for targeting and isolating of cancer cells

The study developed a simple, effective and inexpensive strategy for capturing, enriching and detecting circulating tumor cells (CTCs) by using folic acid (FA) as the targeting molecule instead of antibodies. This work constructed magnetic halloysite nanotubes (MHNTs) coated with biocompatible β-cyclodextrin (CD), and conjugated to FA via a PEG-Ad linker, to specifically capture the FA receptor (FR)-overexpressing cancer cells. The capture efficiencies of MHNTs@β-CD@Ad-PEG-FA for the Skov3, Hela and A549 cancer cells were 96.3%, 97.0% and 95.6% respectively. In addition, the nanoparticles were able to capture very low numbers of the cancer cells (25-500 cells/mL) from PBS and whole blood, as well as selectively capture the cancer cells over normal HEK 293 T cells. Furthermore, the captured cells were viable and grew normally in vitro, indicating the future potential of downstream analyses. This approach can be adapted for different CTCs, once the tumor-specific surface markers are identified and the efficacy of targeting ligands is established. Taken together, FA-conjugated MHNTs nanoparticles are a highly promising tool for isolating CTCs for the diagnosis and treatment of cancer.

Amphipathic β-cyclodextrin nanocarriers serve as intelligent delivery platform for anticancer drug

A novel glutathione-responsive (GSH-responsive) star-like amphiphilic polymer (C₁₂H₂₅)₁₄-β-CD-(S-S-mPEG)₇ (denoted as CCSP) was designed for efficient antitumor drug delivery. The amphiphilic β-cyclodextrin (β-CD) self-polymerize in water to form a sphere with a diameter of 40-50 nm. The secondary hydroxyl groups of β-CD were modified by dodecyl to form a hydrophobic core and the primary hydroxyl groups of β-CD were decorated with PEG through disulfide bond to form a hydrophilic shell. Since the hydrophobic cavity of β-CD was maintained, the hydrophobic core formed by dodecyl as well as cavity of β-CD provided CCSP with a loading content as high as 39.6 wt%. Importantly, DOX@CCSP exhibited low drug leakage and negligible cytotoxicity in non-reductive physiological environment, while it showed rapid release and high cytotoxicity in reductive tumorous environment via the breakage of disulfide bond. In view of the above-mentioned advantages of DOX@CCSP nanocarriers such as high loading content, proper size, favorable stimulus-response release performance and low leakage, it is believed that CCSP may offer great potential to be used as an intelligent nanocarrier for anticancer drug delivery.

Polymethacrylic acid encapsulated TiO2 nanotubes for sustained drug release and enhanced antibacterial activities

A long-term antibacterial and sustained drug release system was fabricated, in which the TNTs acted as the loading platform of NOR and then encapsulated with PMAA.