Temperature and pH-responsive PNIPAM@PAA Nanospheres with a Core-Shell Structure for Controlled Release of Doxorubicin in Breast Cancer Treatment

Stimuli-responsive polymers have been of great interest in the fabrication of advanced drug delivery systems. In this study, a facile approach was developed to synthesize a dually temperature/pH-responsive drug delivery system with a core-shell structure to control the release of doxorubicin (DOX) at the target site. For this purpose, poly(acrylic acid) (PAA) nanospheres were first synthesized using the precipitation polymerization technique and were used as pH-responsive polymeric cores. Then, poly(N-isopropylacrylamide) (PNIPAM) with thermo-responsivity properties was coated on the outer surface of PAA cores via seed emulsion polymerization technique to render monodisperse PNIPAM-coated PAA (PNIPAM@PAA) nanospheres. The optimized PNIPAM@PAA nanospheres with an average particle size of 116.8 nm (PDI= 0.243), had a high negative surface charge (zeta potential= -47.6 mV). Then, DOX was loaded on PNIPAM@PAA nanospheres and the entrapment efficiency (EE) and drug loading (DL) capacity were measured to be 92.7% and 18.5%, respectively. The drug-loaded nanospheres exhibited a low leakage at neutral pH and physiological temperature, but drug release significantly enhanced at acidic pH (pH= 5.5), indicating the tumor-environment responsive drug release behavior of the prepared nanospheres. Also, kinetics studies showed that, the sustained release of DOX from PNIPAM@PAA nanospheres was consistent with the Fickian diffusion mechanism. Moreover, the anticancer efficacy of DOX-loaded nanospheres was evaluated in vitro against MCF-7 breast cancer cells. The obtained results revealed that, the incorporation of DOX into PNIPAM@PAA nanospheres increases its cytotoxicity against cancer cells compared to the free DOX. Our results suggest that, PNIPAM@PAA nanospheres can be considered as a promising vector to release anticancer drugs with dual-stimuli responsivity to pH and temperature.

4D printed multipurpose smart implants for breast cancer management

Breast-conserving surgery (BCS) is the primary strategy for treating early-stage breast cancer; however, the incidence of local recurrence and breast tissue loss negatively impacts patients and survivors. Furthermore, radiotherapy and/or systemic therapies are frequently advised to avoid recidivism and increase the patient's chance of survival, resulting in longer duration of treatments, and unpleasant systemic side effects. Given the poor prognosis and the heterogeneity between individuals and tumors, a patient-centered approach is fundamental. Herein we developed a multipurpose 4D printed implant made of a blend of carboxymethyl cellulose sodium salt (CMC) and cellulose nanocrystals (CNC), loaded with doxorubicin (DOX). To predict printability performance, full rheological characterization was carried out. The smart device was programmed to change size, under swelling, to better fit in the tissue cavity, resulting in a great potential for personalization, thus improving the aesthetic outcomes. The influence of the formulation and printing parameters on the morpho transformation was investigated through the swelling test, confirming the possibility to program the 4D shape. The manufactured implants were characterized by a variety of methods, including in vitro release studies. Lastly, the anticancer activity was conducted in vitro, on MDA-MB-231 cells. Implants promoted an anticancer effect of -58% viability after 72h incubation, even when tested 4 weeks after the printing process. Overall, the morpho transformation and the in vitro studies have shown that the implant could represent a potential strategy for breast cancer following resection, to fill the void in the breast resulting from the surgery and provide an anticancer effect to avoid recurrence.

Micellar Form of a Ferrocene-Containing Camphor Sulfonamide with Improved Aqueous Solubility and Tumor Curing Potential

The discovery of new anticancer drugs with а higher, more specific activity and diminished side effects than the conventional chemotherapeutic agents is a tremendous challenge to contemporary medical research and development. To achieve a pronounced efficacy, the design of antitumor agents can combine various biologically active subunits in one molecule, which can affect different regulatory pathways in cancer cells. We recently demonstrated that a newly synthesized organometallic compound, a ferrocene-containing camphor sulfonamide (DK164), possesses promising antiproliferative activity against breast and lung cancer cells. However, it still encounters the problem of solubility in biological fluids. In this work, we describe a novel micellar form of DK164 with significantly improved solubility in aqueous medium. DK164 was embedded in biodegradable micelles based on a poly(ethylene oxide)-b-poly(α-cinnamyl-ε-caprolactone-co-ε-caprolactone)-b-poly(ethylene oxide) triblock copolymer (PEO113-b-P(CyCL3-co-CL46)-b-PEO113), and the physicochemical parameters (size, size distribution, zeta potential, encapsulation efficiency) and biological activity of the obtained system were studied. We used cytotoxicity assays and flow cytometry to determine the type of cell death, as well as immunocytochemistry to assess the influence of the encapsulated drug on the dynamics of cellular key proteins (p53 and NFkB) and the process of autophagy. According to our results, the micellar form of the organometallic ferrocene derivate (DK164-NP) exhibited several advantages compared to the free substance, such as higher metabolic stability, better cellular uptake, improved bioavailability, and long-term activity, maintaining nearly the same biological activity and anticancer properties of the drug.

Dispersion Performances and Fluorescent Behaviors of Naphthalic Anhydride Doped in Poly(acrylic acid) Frameworks for pH-Sensitive Ibuprofen Delivery via Fractal Evolution

The pH-responsive fluorescent P(1,8-naphthalic anhydride (NA)-acrylic acid (AA)) matrix was successfully prepared by a doping method using poly(acrylic acid) (PAA) as a pH-sensitive polymer and NA as a fluorescent tracer. The fluorescent behaviors of the used NA dispersed in PAA frameworks were demonstrated based on fractal features combined with various characterizations, such as small-angle X-ray scattering (SAXS) patterns, photoluminescence (PL) spectra, scanning electron microscope (SEM) images, thermogravimetry (TG) profiles, Fourier transform infrared (FT-IR) spectroscopy, and time-resolved decays. The effects of NA-doping on the representative fluorescent P(NA-AA) were investigated, in which the fluorescent performance of the doped NA was emphasized. The results indicated that aggregated clusters of the doped NA were gradually serious with an increase in NA doping amount or extension of NA doping time, accompanied by an increase in mass fractal dimension (D_m) values. Meanwhile, the doped NA presented stable fluorescent properties during the swelling-shrinking process of PAA. Ibuprofen (IBU) was used as a model drug, and fractal evolutions of the obtained P(NA-AA) along with the drug loading and releasing behaviors were evaluated via SAXS patterns, in which the drug-loaded P(NA-AA) presented surface fractal (D_s) characteristics, while the D_m value varied from 2.94 to 2.58 during sustained drug-release in pH 2.0, indicating occurrences of its structural transformation from dense to loose with extension of IBU-releasing time. Finally, the cytotoxicity and cellular uptake behaviors of the obtained P(NA-AA) were preliminarily explored. These demonstrations revealed that the resultant P(NA-AA) should be a potential intelligent-responsive drug carrier for targeted delivery.

Molecularly Imprinted Nanomaterials with Stimuli Responsiveness for Applications in Biomedicine

The review aims to summarize recent reports of stimuli-responsive nanomaterials based on molecularly imprinted polymers (MIPs) and discuss their applications in biomedicine. In the past few decades, MIPs have been proven to show widespread applications as new molecular recognition materials. The development of stimuli-responsive nanomaterials has successfully endowed MIPs with not only affinity properties comparable to those of natural antibodies but also the ability to respond to external stimuli (stimuli-responsive MIPs). In this review, we will discuss the synthesis of MIPs, the classification of stimuli-responsive MIP nanomaterials (MIP-NMs), their dynamic mechanisms, and their applications in biomedicine, including bioanalysis and diagnosis, biological imaging, drug delivery, disease intervention, and others. This review mainly focuses on studies of smart MIP-NMs with biomedical perspectives after 2015. We believe that this review will be helpful for the further exploration of stimuli-responsive MIP-NMs and contribute to expanding their practical applications especially in biomedicine in the near future.

Mannosylated poly(acrylic acid)-coated mesoporous silica nanoparticles for anticancer therapy

Although mesoporous silica nanoparticles (MSNs) are widely used as anticancer drug carriers, unmodified MSNs induce off-target effects and at high doses, there are adverse effects of hemolysis because of the interaction with the silanol group on the surface and cells. In this study, we developed doxorubicin (DOX)-loaded MSNs coated with mannose grafted poly (acrylic acid) copolymer (DOX@MSNs-man-g-PAA) to enhance the hemocompatibility and target efficacy to cancer cells. This uniform nanosized DOX@MSNs-man-g-PAA showed sustained and pH-dependent drug release with improved hemocompatibility over the bare MSNs. The uptake of the DOX@MSN-man-g-PAA in breast cancer cells was significantly improved by mannose receptor-mediated endocytosis, which showed significant increasing intracellular ROS and changes in mitochondrial membrane potential. This formulation exhibited superior tumor-suppressing activity in the MDA-MB-231 cells inoculated mice. Overall, the present study suggested the possibility of the copolymer-coated MSNs as drug carriers for cancer therapy.

Precipitation Polymerization: A Powerful Tool for Preparation of Uniform Polymer Particles

Precipitation polymerization (PP) is a powerful tool to prepare various types of uniform polymer particles owing to its outstanding advantages of easy operation and the absence of any surfactant. Several PP approaches have been developed up to now, including traditional thermo-induced precipitation polymerization (TRPP), distillation precipitation polymerization (DPP), reflux precipitation polymerization (RPP), photoinduced precipitation polymerization (PPP), solvothermal precipitation polymerization (SPP), controlled/‘‘living’’ radical precipitation polymerization (CRPP) and self-stabilized precipitation polymerization (2SPP). In this review, a general introduction to the categories, mechanisms, and applications of precipitation polymerization and the recent developments are presented, proving that PP has great potential to become one of the most attractive polymerization techniques in materials science and bio-medical areas.

Multifunctional nanoparticles for targeted delivery of apoptin plasmid in cancer treatment

The systemic toxicity and low efficacy of traditional chemotherapy for hepatocellular carcinoma (HCC) result in poor clinical outcomes. This study was designed to achieve targeted delivery of apoptin plasmid (AP) to liver tumors and killing of cancer cells using multifunctional nanoparticles (MFNPs) having sustained-release properties. The MFNPs featuring a distinct core-shell structure were prepared using poly(lactic-glycolic acid)-ε-polylysine copolymer and loaded with AP by adsorption. Specific targeting of liver tumor cells was achieved by biotinylation of the nanoparticles (NPs), while an improvement in lysosomal escape and nuclear localization enhanced the tumor cell killing capability of AP. Blank MFNPs exhibited good biocompatibility while AP-loaded NPs were found to exert strong inhibitory effects on both tumor cells in vitro and solid tumors in vivo. Taken together, these findings demonstrate a promising route for the development of tumor-targeted NPs which may lead to improved therapeutic strategies for treating HCC.

Enhancing the Kinetic Stability of Polymeric Nanomicelles (PLGA) Using Nano-Montmorillonite for Effective Targeting of Cancer Tumors

The toxic profile of chemical cross-linkers used in enhancing the stability of self-assembled nanomicelles made of amphiphilic polymeric materials hinders their use in clinical applications. This study was aimed to use the layered structure of Na-montmorillonite (MMT) as a stabilizer for nanomicelles made of poly(d,l-lactide-co-glycolide) (PLGA) amphiphilic polymer. The size of Na-MMT was reduced below 40 nm (nano-MMT) by processing in an attritor prior to its incorporation with PLGA. Hybrid PLGA nano-MMT (PM) nanoparticles (NPs) were prepared using dialysis nanoprecipitation. The size distribution was measured using dynamic light scattering (DLS). Loading 1250 μg of the model drug molecule curcumin to PM (PMC) resulted in obtaining 88 nm-sized particles, suitable for passive targeting of cancer tumors. The structure of nano-MMT and its position in PMC were investigated using FT-IR, differential scanning chalorimetry (DSC), XRF, XRD, ESEM, and EDAX assays, all of which showed the exfoliated structure of nano-MMT incorporated with both hydrophilic and hydrophobic blocks of PLGA. Curcumin was mutually loaded to PLGA and nano-MMT. This firm incorporation caused a serious extension in the release of curcumin from PMC compared to PLGA (PC). Fitting the release profile to different mathematical models showed the remarkable role of nano-MMT in surface modification of PLGA NPs. The ex vivo dynamic model showed the enhanced stability of PMC in simulated blood flow, while cytotoxicity assays showed that nano-MMT does not aggravate the good toxic profile of PLGA but improves the anticancer effect of payload. Nano-MMT could be used as an effective nontoxic stabilizer agent for self-assembled NPs.

Microfluidic-assisted nanoprecipitation of biodegradable nanoparticles composed of PTMC/PCL (co)polymers, tannic acid and doxorubicin for cancer treatment

This study was aimed towards the development of a novel microfluidic approach for the preparation of (co)polymeric and hybrid nanoparticles (NPs) composed of (co)polymers/tannic acid (TA) in the microfluidic flow-focusing glass-capillary device. The MiliQ water was used as water phase, whereas the organic phase was composed of poly(ε-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) homopolymers and (co)polymers with different proportion of comonomers which were prepared via enzymatic polymerization that allows avoiding the usage of potentially toxic catalyst. To prepare hybrid NPs, TA was additionally added to the organic phase. Subsequently, as a result of mixing between these distinct phases in microfluidic channels, the nanoprecipitation in the form of spherical NPs occurs. The size of NPs was tuned over the range of 140-230 nm by controlling phase flow rates and the composition of NPs. Moreover, the release studies of the encapsulated anticancer drug doxorubicin (DOX) demonstrated that the drug release is greatly influenced by the (co)polymers composition, their molecular weight, NPs size, and the presence of TA. The antitumor activities of the (co)polymeric and hybrid NPs toward breast cancer cells (MCF-7) were tested in vitro. Among all tested formulation, the NPs composed of PCL/TA most efficiently inhibit the cell proliferation of MCF-7 cells, most importantly, their efficiency was higher than free DOX. The proposed strategy may provide an efficient alternative for the construction of nanocarriers with great potential in anticancer therapy.

Multifunctional and stimuli-responsive nanocarriers for targeted therapeutic delivery

INTRODUCTION

Nanocarrier-based delivery systems offer multiple benefits to overcome limitations of the traditional drug dosage forms, such as protection of the drug, enhanced bioavailability, targeted delivery to disease site, etc. Nanocarriers have exhibited tremendous successes in targeted delivery of therapeutics to the desired tissues and cells with improved bioavailability, high drug loading capacity, enhanced intracellular delivery, and better therapeutic effect. A specific design of stimuli-responsive nanocarriers allows for changing their structural and physicochemical properties in response to exogenous and endogenous stimuli. These nanocarriers show a promise in site specific controlled release of therapeutics under certain physiological conditions or external stimuli.

AREAS COVERED

This review highlights recent progresses on the multifunctional and stimuli-sensitive nanocarriers for targeted therapeutic drug delivery applications.

EXPERT OPINION

The progress from single functional to multifunctional nanocarriers has shown tremendous potential for targeted delivery of therapeutics. On our opinion, the future of targeted delivery of drugs, nucleic acids, and other substances belongs to the site-targeted multifunctional and stimuli-based nanoparticles with controlled release. Targeting of nanocarriers to the disease site enhance the efficacy of the treatment by delivering more therapeutics specifically to the affected cells and substantially limiting adverse side effects upon healthy organs, tissues, and cells.