Microneedle‐Array Patch Fabricated with Enzyme‐Free Polymeric Components Capable of On‐Demand Insulin Delivery

Achieving persistent glycemic control in a painless and convenient way is the ultimate goal of diabetes management. Herein, an “enzyme‐free” polymeric microneedle (MN)‐array patch composed of a boronate‐containing hydrogel semi‐interpenetrated by biocompatible silk fibroin is developed. Consistent with the previous reports, the presence of the boronate‐hydrogel allows for glucose‐responsive diffusion‐control of insulin, while the crystalline fibroin component serves as a matrix‐stiffener to validate skin penetration. Remarkably, this “enzyme‐free” smart artificial on‐skin pancreas prototype remains stable for at least 2 months in an aqueous environment. Furthermore, it establishes sustained as well as acute glucose‐responsive insulin delivery, and is to the authors' knowledge, the first successful material design addressing such two technical challenges at once on an MN format. This long‐acting, on‐demand insulin delivery technology may offer a candidate for a next‐generation diabetes therapy that is remarkably stable, safe, economically efficient, and capable of providing both acute‐ and continuous glycemic control in a manner minimally dependent on patient compliance.     

Voltage‐Gated Closed‐Loop Control of Small‐Molecule Release from Alumina‐Coated Nanoporous Gold Thin Film Electrodes

Precise timing and dosing of potent small‐molecule drugs carries significant potential for effective pharmaceutical management of disorders that exhibit time‐varying therapeutic windows such as epilepsy. This study demonstrates the use of alumina‐coated nanoporous gold (np‐Au) thin film electrodes for iontophoretic release of fluorescein as a small‐molecule drug surrogate with picogram dosing and a few seconds temporal resolution. A custom microfluidic platform is engineered to trigger molecular release from an integrated np‐Au chip and monitor the resulting time‐varying fluorescein concentration. Following a systematic study of the influence of applied voltage on loading capacity and release kinetics, a LabVIEW‐based closed‐loop control interface is employed to demonstrate voltage‐gated fluorescein release with preprogrammed arbitrary concentrations waveforms.     

Bioengineered Extracellular Membranous Nanovesicles for Efficient Small‐Interfering RNA Delivery: Versatile Platforms for Stem Cell Engineering and In Vivo Delivery

Naturally derived nanovesicles secreted from various cell types and found in body fluids can provide effective platforms for the delivery of various cargoes because of their intrinsic ability to be internalized for intercellular signal transmission and membrane recycling. In this study, the versatility of bioengineered extracellular membranous nanovesicles as potent carriers of small‐interfering RNAs (siRNAs) for stem cell engineering and in vivo delivery has been explored. Here, exosomes have been engineered, one of the cell‐derived vesicle types, to overexpress exosomal proteins fused with cell‐adhesion or cell‐penetrating peptides for enhanced intracellular gene transfer. To devise a more effective delivery system with potential for mass production, a new siRNA delivery system has also been developed by artificially inducing the outward budding of plasma membrane nanovesicles. Those nanovesicles have been engineered by overexpressing E‐cadherin to facilitate siRNA delivery to human stem cells with resistance to intracellular gene transfer. Both types of engineered nanovesicles deliver siRNAs to human stem cells for lineage specification with negligible cytotoxicity. The nanovesicles are efficient in delivering siRNA in vivo, suggesting feasibility for gene therapy. Cell‐derived, bioengineered nanovesicles used for siRNA delivery can provide functional platforms enabling effective stem cell therapeutics and in vivo gene therapy.     

Biocompatible,Uniform, and Redispersible Mesoporous Silica Nanoparticles for Cancer‐Targeted Drug Delivery In Vivo

Engineering multifunctional nanocarriers for targeted drug delivery shows promising potentials to revolutionize the cancer chemotherapy. Simple methods to optimize physicochemical characteristics and surface composition of the drug nanocarriers need to be developed in order to tackle major challenges for smooth translation of suitable nanocarriers to clinical applications. Here, rational development and utilization of multifunctional mesoporous silica nanoparticles (MSNPs) for targeting MDA‐MB‐231 xenograft model breast cancer in vivo are reported. Uniform and redispersible poly(ethylene glycol)‐incorporated MSNPs with three different sizes (48, 72, 100 nm) are synthesized. They are then functionalized with amino‐β‐cyclodextrin bridged by cleavable disulfide bonds, where amino‐β‐cyclodextrin blocks drugs inside the mesopores. The incorporation of active folate targeting ligand onto 48 nm of multifunctional MSNPs (PEG‐MSNPs48‐CD‐PEG‐FA) leads to improved and selective uptake of the nanoparticles into tumor. Targeted drug delivery capability of PEG‐MSNPs48‐CD‐PEG‐FA is demonstrated by significant inhibition of the tumor growth in mice treated with doxorubicin‐loaded nanoparticles, where doxorubicin is released triggered by intracellular acidic pH and glutathione. Doxorubicin‐loaded PEG‐MSNPs48‐CD‐PEG‐FA exhibits better in vivo therapeutic efficacy as compared with free doxorubicin and non‐targeted nanoparticles. Current study presents successful utilization of multifunctional MSNP‐based drug nanocarriers for targeted cancer therapy in vivo.     

Self‐Assembling Peptide as a Potential Carrier for Hydrophobic Anticancer Drug Ellipticine: Complexation,Release and In Vitro Delivery

The self‐assembling peptide EAK16‐II is capable of stabilizing hydrophobic compounds to form microcrystal suspensions in aqueous solution. Here, the ability of this peptide to stabilize the hydrophobic anticancer agent ellipticine is investigated. The formation of peptide‐ellipticine suspensions is monitored with time until equilibrium is reached. The equilibration time is found to be dependent on the peptide concentration. When the peptide concentration is close to its critical aggregation concentration, the equilibration time is minimal at 5 h. With different combinations of EAK16‐II and ellipticine concentrations, two molecular states (protonated or cyrstalline) of ellipticine could be stabilized. These different states of ellipticine significantly affect the release kinetics of ellipticine from the peptide‐ellipticine complex into the egg phosphatidylcholine vesicles, which are used to mimic cell membranes. The transfer rate of protonated ellipticine from the complex to the vesicles is much faster than that of crystalline ellipticine. This observation may also be related to the size of the resulting complexes as revealed from the scanning electron micrographs. In addition, the complexes with protonated ellipticine are found to have a better anticancer activity against two cancer cell lines, A549 and MCF‐7. This work forms the basis for studies of the peptide‐ellipticine suspensions in vitro and in vivo leading to future development of self‐assembling peptide‐based delivery of hydrophobic anticancer drugs.     

Phase‐Transition Microneedle Patches for Efficient and Accurate Transdermal Delivery of Insulin

Utilizing the unique virtue of polyvinyl alcohol (PVA) of forming microcrystalline domains as the cross‐linking junctions, a new microneedle system, phase‐transition microneedle (PTM) patch, is invented, which enables highly efficient transdermal delivery of insulin without depositing the needle tip materials to the skin. PTM, formed of biocompatible PVA as the main component, is sufficiently strong for its needle tip to penetrate the epidermis in the dry state, release preloaded cargos by absorbing body fluid in the dermis layer nearly as fast as subcutaneous injection, and retain mechanical toughness in the hydrated state to ensure complete removal from the skin. The microcrystalline cross‐linking enables a protein‐friendly fabrication process free of hazardous cross‐linking agents required for chemical and ionic cross‐linking. Pharmacokinetic and efficacy studies of insulin‐loaded PTM using pig models indicate a transdermal bioavailability over 20%, similar deviations and peak width, only 18 min behind Tmax, and lower glycated hemoglobin (HbA_1c) as compared with injection pens. The complete removability of hydrated needle tips may endow PTM with an additional safety insurance, terminating medication whenever hypoglycemia becomes a concern. PTM patch is practically applicable to a variety of protein/peptide medicines requiring frequent dosing by offering painless administration, freedom of refrigeration, and minimal safety concerns.     

In Situ Generated Gold Nanoparticle Hybrid Polymersomes for Water‐Soluble Chemotherapeutics: Inhibited Leakage and pH‐Responsive Intracellular Release

Drug leakage in blood circulation is generally a serious concern to polymersomes when loading water‐soluble chemotherapeutics. If packing density of polymersome membrane is strengthened, premature drug release will be inhibited. Therefore, synthesis of a series of amphiphilic polyphosphazenes (PNPs) with 2‐diethylaminoethyl 4‐aminobenzoate (DEAB) as hydrophobic side groups and amino‐terminal poly(ethylene glycol) (NH₂‐PEG₂₀₀₀) as hydrophilic chains is presented. By controlling the ratio of DEAB to NH₂‐PEG₂₀₀₀, the optimal PNP‐3 is screened to ensure polymersome formation and high loading of doxorubicin hydrochloride (DOX·HCl). In situ generation method is initially employed to introduce gold nanoparticles (AuNPs) into vesicles' lamella, which can homogeneously distribute among DEAB sides via coordination interaction and act as inorganic cross‐linkers to aggregate polymer chains. Drug leakage of resultant AuNP hybrid PNP‐3 polymersome (IAuPNP‐3) at pH 7.4 is effectively alleviated and the systemic circulation time of DOX·HCl in mice is obviously prolonged. Besides, pH‐responsive drug release, due to the protonation of tertiary amine in DEAB, contributes to fast intracellular action. Based on the cooperation of these functions, DOX·HCl‐loaded IAuPNP‐3 finally achieves the highest in vivo antitumor efficacy compared with free DOX·HCl, drug‐loaded PNP, or EAuPNP prepared by prepreparation AuNPs method.     

Chitosan–Alginate Microcapsules Provide Gastric Protection and Intestinal Release of ICAM‐1‐Targeting Nanocarriers,Enabling GI Targeting In Vivo

When administered intravenously, active targeting of drug nanocarriers (NCs) improves biodistribution and endocytosis. Targeting may also improve NC oral delivery to treat gastrointestinal (GI) pathologies or for systemic absorption. However, GI instability of targeting moieties compromises this strategy. This study explores whether encapsulation of antibody‐coated NCs in microcapsules would protect against gastric degradation, providing NC release and targeting in intestinal conditions. Nanoparticles coated with antibodies against intercellular adhesion molecule‐1 (anti‐ICAM) or nonspecific immunoglobulin G (IgG) are encapsulated in chitosan (shell) ‐ alginate (core) microcapsules. Encapsulation efficiency is >95% and NC relase from microcapsules in storage is <10%. There is minimal NC release at gastric pH (<10%) and burst release at intestinal pH (75%–85%). Encapsulated NCs afford increased protection against degradation (threefold to fourfold) and increased cell targeting (8–20‐fold) after release versus the nonencapsulated NCs. Mouse oral gavage shows that microencapsulation provides 38%–65% greater protection of anti‐ICAM NCs in the GI tract, 40% lower gastric retention, and fourfold to ninefold enhanced intestinal biodistribution versus nonencapsulated NCs. Therefore, microencapsulation of antibody‐targeted NCs may enable active targeting strategies to be effective in the context of oral drug delivery.     

Hierarchical Spiky Microstraws‐Integrated Microfluidic Device for Efficient Capture and In Situ Manipulation of Cancer Cells

Techniques for capturing circulating tumor cells (CTCs) play an important role in cancer diagnosis. Recently, various 3D micro/nanostructures have been applied for effective CTC detection, yet in situ manipulation of the captured cancer cells on micro/nano‐structural substrates is rarely achieved. In this work, a hierarchical spiky microstraw array (HS‐MSA)‐integrated microfluidic device is demonstrated that possessed dual functions of cancer cell capture and in situ chemical manipulations of the captured cells. The 3D micro/nanostructure of HS‐MSA could capture cancer cells with high efficiency (≈84%) and strong specificity. Based on the HS‐MSA‐integrated microfluidic device, extracellular drug delivery to the captured cancer cells is achieved in situ with excellent spatial, dose, and temporal controls. In addition, a drug‐screening assay on the captured cancer cells is implemented to investigate the cell apoptosis behavior under the microstraw‐mediated delivery of staurosporine (STS). This microfluidic system not only presents tremendous potential for CTCs detection technology, but also opens up new opportunities for high‐throughput drug screening on cancer cells and understanding the cellular activity.