Sequential Flash NanoPrecipitation for the scalable formulation of stable core-shell nanoparticles with core loadings up to 90

Polyester nanoparticles delivering chemotherapeutics: Learning from the past and looking to the future to enhance their clinical impact in tumor therapy

Polymeric nanoparticles (NPs), specifically those comprised of biodegradable and biocompatible polyesters, have been heralded as a game-changing drug delivery platform. In fact, poly(α-hydroxy acids) such as polylactide (PLA), poly(lactide-co-glycolide) (PLGA), and poly(ε-caprolactone) (PCL) have been heavily researched in the past three decades as the material basis of polymeric NPs for drug delivery applications. As materials, these polymers have found success in resorbable sutures, biodegradable implants, and even monolithic, biodegradable platforms for sustained release of therapeutics (e.g., proteins and small molecules) and diagnostics. Few fields have gained more attention in drug delivery through polymeric NPs than cancer therapy. However, the clinical translational of polymeric nanomedicines for treating solid tumors has not been congruent with the fervor or funding in this particular field of research. Here, we attempt to provide a comprehensive snapshot of polyester NPs in the context of chemotherapeutic delivery. This includes a preliminary exploration of the polymeric nanomedicine in the cancer research space. We examine the various processes for producing polyester NPs, including methods for surface-functionalization, and related challenges. After a detailed overview of the multiple factors involved with the delivery of NPs to solid tumors, the crosstalk between particle design and interactions with biological systems is discussed. Finally, we report state-of-the-art approaches toward effective delivery of NPs to tumors, aiming at identifying new research areas and re-evaluating the reasons why some research avenues have underdelivered. We hope our effort will contribute to a better understanding of the gap to fill and delineate the future research work needed to bring polyester-based NPs closer to clinical application. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Flash nanoprecipitation assisted self-assembly of ionizable lipid nanoparticles for nucleic acid delivery

Ionizable lipid nanoparticles (LNPs) have emerged as a powerful tool for the intracellular delivery of nucleic acids. Following the recent success of LNP-based siRNA therapeutics and mRNA vaccines, the use of ionizable lipids for nucleic acid delivery has tremendously increased. Here, we introduce a flash nanoprecipitation (FNP) approach using the confined impingement (CIJ) mixer to stably self-assemble ionizable LNPs. To validate this approach, we employed three clinically relevant LNP formulations containing SM102, ALC0315, and DLin-MC3-DMA as ionizable lipids. FNP-assembled LNPs showed >95% encapsulation efficiency of mRNA and siRNA payloads and particle sizes below 150 nm. SM102 or ALC0315 LNPs demonstrated efficient delivery of mRNA into immune cells in vitro and to lymphoid organs in vivo, whereas Dlin-MC3-DMA LNPs allowed effective intracellular siRNA delivery with great functional ability. The FNP technique could economically produce LNPs in smaller volumes that are highly suitable for the discovery phase.

Flash nanoprecipitation allows easy fabrication of pH-responsive acetalated dextran nanoparticles for intracellular release of payloads

Acetalated dextran (Ac-Dex) nanoparticles are currently of immense interest due to their sharp pH-responsive nature and high biodegradability. Ac-Dex nanoparticles are often formulated through single- or double-emulsion methods utilizing polyvinyl alcohol as the stabilizer. The emulsion methods utilize toxic organic solvents such as dichloromethane or chloroform and require multi-step processing to form stable Ac-Dex nanoparticles. Here, we introduce a simple flash nanoprecipitation (FNP) approach that utilizes a confined impinging jet mixer and a non-toxic solvent, ethanol, to form Ac-Dex nanoparticles rapidly. Ac-Dex nanoparticles were stabilized using nonionic PEGylated surfactants, D-α-Tocopherol polyethylene glycol succinate (TPGS), or Pluronic (F-127). Ac-Dex nanoparticles formed using FNP were highly monodisperse and stably encapsulated a wide range of payloads, including hydrophobic, hydrophilic, and macromolecules. When lyophilized, Ac-Dex TPGS nanoparticles remained stable for at least one year with greater than 80% payload retention. Ac-Dex nanoparticles were non-toxic to cells and achieved intracellular release of payloads into the cytoplasm. In vivo studies demonstrated a predominant biodistribution of Ac-Dex TPGS nanoparticles in the liver, lungs, and spleen after intravenous administration. Taken together, the FNP technique allows easy fabrication and loading of Ac-Dex nanoparticles that can precisely release payloads into intracellular environments for diverse therapeutic applications. pH-responsive Acetalateddextran can be formulated using nonionic surfactants, such as TPGS or F-127, for intracellular release of payloads. Highly monodisperse and stable nanoparticles can be created through the simple, scalable flash nanoprecipitation technique, which utilizes a confined impingement jet mixer.

Flash NanoPrecipitation as an Agrochemical Nanocarrier Formulation Platform: Phloem Uptake and Translocation after Foliar Administration

The increasing severity of pathogenic and environmental stressors that negatively affect plant health has led to interest in developing next-generation agrochemical delivery systems capable of precisely transporting active agents to specific sites within plants. In this work, we adapt Flash NanoPrecipitation (FNP), a scalable nanocarrier (NC) formulation technology used in the pharmaceutical industry, to prepare organic core-shell NCs and study their efficacy as foliar or root delivery vehicles. NCs ranging in diameter from 55 to 200 nm, with surface zeta potentials from -40 to +40 mV, and with seven different shell material properties were prepared and studied. Shell materials included synthetic polymers poly(acrylic acid), poly(ethylene glycol), and poly(2-(dimethylamino)ethyl methacrylate), naturally occurring compounds fish gelatin and soybean lecithin, and semisynthetic hydroxypropyl methylcellulose acetate succinate (HPMCAS). NC cores contained a gadolinium tracer for tracking by mass spectrometry, a fluorescent dye for tracking by confocal microscopy, and model hydrophobic compounds (alpha tocopherol acetate and polystyrene) that could be replaced by agrochemical payloads in subsequent applications. After foliar application onto tomato plants with Silwet L-77 surfactant, internalization efficiencies of up to 85% and NC translocation efficiencies of up to 32% were observed. Significant NC trafficking to the stem and roots suggests a high degree of phloem loading for some of these formulations. Results were corroborated by confocal microscopy and synchrotron X-ray fluorescence mapping. NCs stabilized by cellulosic HPMCAS exhibited the highest degree of translocation, followed by formulations with a significant surface charge. The results from this work indicate that biocompatible materials like HPMCAS are promising agrochemical delivery vehicles in an industrially viable pharmaceutical nanoformulation process (FNP) and shed light on the optimal properties of organic NCs for efficient foliar uptake, translocation, and delivery.

Integrated continuous manufacturing of inhalable remdesivir nanoagglomerate dry powders: Design, optimization and therapeutic potential for respiratory viral infections

While inhalable nanoparticle-based dry powders have demonstrated promising potential as next-generation respiratory medicines, erratic particle redispersibility and poor manufacturing reproducibility remain major hurdles hindering their translation from bench to bedside. We developed a one-step continuous process for fabricating inhalable remdesivir (RDV) nanoagglomerate dry powder formulations by integrating flash nanoprecipitation and spray drying. The nanosuspension formulation was optimized using a three-factor Box-Behnken design with a z-average particle size of 233.3 ± 2.3 nm and < 20% size change within six hours. The optimized inhalable nanoagglomerate dry powder formulation produced by spray drying showed adequate aqueous redispersibility (Sf/Si = 1.20 ± 0.01) and in vitro aerosol performance (mass median aerodynamic diameter of 3.80 ± 0.58 µm and fine particle fraction of 39.85 ± 10.16%). In A549 cells, RDV nanoparticles redispersed from the inhalable nanoagglomerate powders displayed enhanced and accelerated RDV cell uptake and negligible cytotoxicity at therapeutic RDV concentrations. No statistically significant differences were observed in the critical quality attributes of the inhalable nanoagglomerate powders produced from the continuous manufacturing and standalone batch modes. This work demonstrates the feasibility of large-scale continuous manufacturing of inhalable nanoagglomerate dry powder formulations, which pave the way for their clinical translation.

Triplet-Triplet Annihilation Upconversion-Based Oxygen Sensors to Overcome the Limitation of Autofluorescence

Autofluorescence is one of the many challenges in bioimaging as it can mask the emission from fluorescent probes or markers, a limitation that can be overcome via upconversion. Herein, we have developed a nanosensor that uses triplet-triplet annihilation upconversion to optically report changes in the dissolved oxygen concentration. Using a sensitizer-annihilator dye pairing of platinum(II) octaethylporphyrin and 9,10-diphenylanthracene, we monitored the oxygen consumption (as a proxy for metabolic activity) over time in a biological system─Saccharomyces cerevisiae (brewing yeast). The nanosensor demonstrated good reversibility over multiple cycles and showed good signal and colloidal stability when tested over the course of 7 days, and it was sensitive to dissolved oxygen from 0.00 to 3.17 mg/L O2. Additionally, there was no signal overlap between the nanosensor emission and S. cerevisiae autofluorescence, thus underscoring the utility of upconversion as a facile and economical means of overcoming autofluorescence.