Design of Smart Size-, Surface-, and Shape-Switching Nanoparticles to Improve Therapeutic Efficacy

Multiple biological barriers must be considered in the design of nanomedicines, including prolonged blood circulation, efficient accumulation at the target site, effective penetration into the target tissue, selective uptake of the nanoparticles into target cells, and successful endosomal escape. However, different particle sizes, surface chemistries, and sometimes shapes are required to achieve the desired transport properties at each step of the delivery process. In response, this review highlights recent developments in the design of switchable nanoparticles whose size, surface chemistry, shape, or a combination thereof can be altered as a function of time, a disease-specific microenvironment, and/or via an externally applied stimulus to enable improved optimization of nanoparticle properties in each step of the delivery process. The practical use of such nanoparticles in chemotherapy, bioimaging, photothermal therapy, and other applications is also discussed.

Cyclic Anhydrides as Powerful Tools for Bioconjugation and Smart Delivery

Cyclic anhydrides are potent tools for bioconjugation; therefore, they are broadly used in the functionalization of biomolecules and carriers. The pH-dependent stability and reactivity, as well as the physical properties, can be tuned by the structure of the cyclic anhydride used; thus, their application in smart delivery systems has become very important. This review intends to cover the last updates in the use of cyclic anhydrides as pH-sensitive linkers, their differences in reactivity, and the latest applications found in bioconjugation chemistry or chemical biology, and when possible, in drug delivery.

Cancer-Targeted Controlled Delivery of Chemotherapeutic Anthracycline Derivatives Using Apoferritin Nanocage Carriers

The interactions of chemotherapeutic drugs with nanocage protein apoferritin (APO) are the key features in the effective encapsulation and release of highly toxic drugs in APO-based controlled drug delivery systems. The encapsulation enables mitigating the drugs' side effects, collateral damage to healthy cells, and adverse immune reactions. Herein, the interactions of anthracycline drugs with APO were studied to assess the effect of drug lipophilicity on their encapsulation excess n and in vitro activity. Anthracycline drugs, including doxorubicin (DOX), epirubicin (EPI), daunorubicin (DAU), and idarubicin (IDA), with lipophilicity P from 0.8 to 15, were investigated. We have found that in addition to hydrogen-bonded supramolecular ensemble formation with n = 24, there are two other competing contributions that enable increasing n under strong polar interactions (APO(DOX)) or under strong hydrophobic interactions (APO(IDA) of the highest efficacy). The encapsulation/release processes were investigated using UV-Vis, fluorescence, circular dichroism, and FTIR spectroscopies. The in vitro cytotoxicity/growth inhibition tests and flow cytometry corroborate high apoptotic activity of APO(drugs) against targeted MDA-MB-231 adenocarcinoma and HeLa cells, and low activity against healthy MCF10A cells, demonstrating targeting ability of nanodrugs. A model for molecular interactions between anthracyclines and APO nanocarriers was developed, and the relationships derived compared with experimental results.

Advanced drug-delivery systems: mechanoresponsive nanoplatforms applicable in atherosclerosis management

Nanoplatforms have been used extensively as advanced carriers to enhance the effectiveness of drug delivery, mostly through passive aggregation provided by the enhanced permeability and retention effect. Mechanical stimuli provide a robust strategy to bolster drug delivery performance by increasing the accumulation of nanoplatforms at the lesion sites, facilitating on-demand cargo release and providing theranostic aims. In this review, we focus on recent advances of mechanoresponsive nanoplatforms that can accomplish targeted drug delivery, and subsequent drug release, under specific stimuli, either endogenous (shear stress) or exogenous (magnetic field and ultrasound), to synergistically combat atherosclerosis at the molecular level.

Nanomaterials multifunctional behavior for enlightened cancer therapeutics

Cancer is an outrageous disease with uncontrolled differentiation, growth, and migration to the other parts of the body. It is the second-most common cause of death both in the U.S. and worldwide. Current conventional therapies, though much improved and with better prognosis, have several limitations. Chemotherapeutic agents, for instance, are cytotoxic to both tumor and healthy cells, and the non-specific distribution of drugs at tumor sites limits the dose administered. Nanotechnology, which evolved from the coalescence and union of varied scientific disciplines, is a novel science that has been the focus of much research. This technology is generating more effective cancer therapies to overcome biomedical and biophysical barriers against standard interventions in the body; its unique magnetic, electrical, and structural properties make it a promising tool. This article reviews endogenous- and exogenous-based stimulus-responsive drug delivery systems designed to overcome the limitations of conventional therapies. The article also summarizes the study of nanomaterials, including polymeric, gold, silver, magnetic, and quantum dot nanoparticles. Though an array of drug delivery systems has so far been proposed, there remain many challenges and concerns that should be addressed in order to fill the gaps in the field. Prominence is given to drug delivery systems that employ external- and internal-based stimuli and that are emerging as promising tools for cancer therapeutics in clinical settings.

Atherosclerosis Treatment with Stimuli-Responsive Nanoagents: Recent Advances and Future Perspectives

Atherosclerosis is the root of approximately one-third of global mortalities. Nanotechnology exhibits splendid prospects to combat atherosclerosis at the molecular level by engineering smart nanoagents with versatile functionalizations. Significant advances in nanoengineering enable nanoagents to autonomously navigate in the bloodstream, escape from biological barriers, and assemble with their nanocohort at the targeted lesion. The assembly of nanoagents with endogenous and exogenous stimuli breaks down their shells, facilitates intracellular delivery, releases their cargo to kill the corrupt cells, and gives imaging reports. All these improvements pave the way toward personalized medicine for atherosclerosis. This review systematically summarizes the recent advances in stimuli-responsive nanoagents for atherosclerosis management and its progress in clinical trials.

Acid-Activated Melittin for Targeted and Safe Antitumor Therapy

Melittin (MLT), as a natural active biomolecule, can penetrate the tumor cell membrane to play a role in cancer treatment and will attract more attention in future development of antitumor drugs. The main component of natural bee venom MLT was modified by introducing a pH-sensitive amide bond between the 2,3-dimethyl maleimide (DMMA) and the lysine (Lys) of MLT (MLT-DMMA). MLT and its corresponding modified peptide MLT-DMMA were used for antitumor and biocompatibility validation. The biomaterial characteristics were tested by MALDI-TOF MS, ¹H NMR, IUPAC and HPLC, cell viability, hemolytic and animal experiment safety evaluation. Compared with the primary melittin, the modified peptide showed decreased surface charge and low cytotoxicity in physiological conditions. Moreover, cell assays confirmed the acid-activated conversion of amide bond resulting in adequate safety during delivery and timely antitumor activity in tumor lesions. Thus, MLT-DMMA provided a feasible platform to improve the targeted and safe antitumor applications.

Hierarchical mesoporous silica nanoparticles for tailorable drug release

In order to modulate the drug release profiles, the hierarchical mesoporous silica nanoparticles (HMSNs) are fabricated by a two-step synthetic process. The HMSNs exhibit uniform spherical morphology with nanoscaled size, well mono-dispersed size distribution, and smooth surface. Because of the hierarchical pore structures with different mesoporous sizes and morphologies (partial open and partial blocked pores), the HMSNs can release the loaded drug in a controlled manner. The hierarchical mesoporous structures directed drug release profiles suggest a feasible strategy to tailor drug release behaviors. Meanwhile, the HMSNs exhibit good biocompatibility. Therefore, the HMSNs having tailorable drug release capacity would be a potential candidate to improve their therapeutic efficiency for drug delivery systems.

Intelligent Drug Delivery System Based on Mesoporous Silica Nanoparticles Coated with an Ultra-pH-Sensitive Gatekeeper and Poly(ethylene glycol)

Mesoporous silica nanoparticles (MSNs) exhibit significant advantages for efficient drug/gene delivery but it is hard for simple MSNs to deliver the loaded drug to the target sites of disease. Considering that there are some well-known pH differences in the body, it is a useful strategy to modify the exterior surface of MSNs with stimuli-responsive gatekeepers to realize open-close transformation of their mesopores. In this work, multifunctional pH-sensitive MSNs were designed with mixed polymeric coatings, that is, poly(ethylene glycol) (PEG) as a dispersity-enhancer and poly(2-(pentamethyleneimino)ethyl methacrylate) (PPEMA) as an ultra-pH-sensitive gatekeeper. Enhanced dispersity, high drug loading capacity, long-circulation time, pH-triggered targeting, and better cellular uptake of the multifunctional MSNs make them potential candidates for pH-sensitive drug delivery such as tumor therapy.

Dual pH-responsive micelles with both charge-conversional property and hydrophobic–hydrophilic transition for effective cellular uptake and intracellular drug release

Two types of diblock copolymers are synthesized to construct dual pH-responsive micelles with a charge-conversional property for effective drug delivery.

Synergetic enhancement of antitumor efficacy with charge-reversal and reduction-sensitive polymer micelles

An amphiphilic block copolymer PLA-SS-PAEMA/DMMA was used to encapsulate and deliver Doxorubicin for synergetic enhancement of antitumor efficacy by the combinational effect of charge-reversal on cellular uptake and reduction-sensitivity on intracellular DOX release.

Dual acid-responsive supramolecular nanoparticles as new anticancer drug delivery systems

In this article, a dual acid-responsive drug delivery system has been fabricated via simple host–guest recognition.

A hollow porous magnetic nanocarrier for efficient near-infrared light- and pH-controlled drug release

A NIR light and pH dual responsive nanocarrier was fabricated for anti-cancer drug delivery as well as MRI and fluorescence cell imaging.