All-Silica Submicrometer Colloidosomes for Cargo Protection and Tunable Release

Tumor Microenvironment Modulating CaCO3 -Based Colloidosomal Microreactors Can Generally Reinforce Cancer Immunotherapy

Tumor hypoxia and acidity, two general features of solid tumors, are known to have negative effect on cancer immunotherapy by directly causing dysfunction of effector immune cells and promoting suppressive immune cells inside tumors. Herein, a multifunctional colloidosomal microreactor is constructed by encapsulating catalase within calcium carbonate (CaCO3 ) nanoparticle-assembled colloidosomes (abbreviated as CaP CSs) via the classic double emulsion method. The yielded CCaP CSs exhibit well-retained proton-scavenging and hydrogen peroxide decomposition performances and can thus neutralize tumor acidity, attenuate tumor hypoxia, and suppress lactate production upon intratumoral administration. Consequently, CCaP CSs treatment can activate potent antitumor immunity and thus significantly enhance the therapeutic potency of coloaded anti-programmed death-1 (anti-PD-1) antibodies in both murine subcutaneous CT26 and orthotopic 4T1 tumor xenografts. In addition, such CCaP CSs treatment also markedly reinforces the therapeutic potency of epidermal growth factor receptor expressing chimeric antigen receptor T (EGFR-CAR-T) cells toward a human triple-negative breast cancer xenograft by promoting their tumor infiltration and effector cytokine secretion. Therefore, this study highlights that chemical modulation of tumor acidity and hypoxia can collectively reverse tumor immunosuppression and thus significantly potentiate both immune checkpoint blockade and CAR-T cell immunotherapies toward solid tumors.

Three-Fluid Nozzle Spray Drying Strategy for Efficient Fabrication of Functional Colloidosomes

Colloidosomes as Pickering emulsion microcapsules are expected to serve various applications, including encapsulation of drugs and loading of functional materials. Normally, when using colloidosomes for drug encapsulation, the latex particles as shell materials need to be mixed with drugs before the assembly process. However, this procedure may cause aggregation of latex particles, thereby resulting in disordered assembled shells or a low loading efficiency. Herein, we propose a three-fluid nozzle spray drying process to efficiently assemble latex particles of P(styrene (St)-co-butyl acrylate (BA)) into colloidosomes. The three-fluid nozzle spray drying equipment allows for the preparation for drug encapsulation without advance mixing of drug and shell materials. This strategy enables the construction of colloidosomes with uniform and controllable pores and the loading of functional materials. The effects of the compressed air flow rate, inlet temperature, feed rate, and solid content were explored, revealing the formation mechanism of colloidosomes during the spray drying process. Doxycycline hydrochloride (DH) was encapsulated in colloidosomes for controllable release, and the sustained release time is up to 100 h. The release rate can be adjusted by varying the glass transition temperature (T_g) and size of latex particles. Furthermore, Fe₃O₄ nanoparticle (NP)-loaded colloidosomes were constructed by this strategy. The magnetic response intensity of colloidosomes can be modulated by varying the amount of Fe₃O₄ NPs. The anticancer drug encapsulation and loading of other functional particles were also explored to expand applications.

Preparation of Multicore Colloidosomes: Nanoparticle-Assembled Capsules with Adjustable Size, Internal Structure, and Functionalities for Oil Encapsulation

Colloidosomes, also known as Pickering emulsion capsules, have attracted attention for encapsulation of hydrophilic and hydrophobic actives. However, current preparation methods are limited to single core structures and require the use of modified/engineered nanoparticles for forming the shell. Here, we report a fast, simple, and versatile method for producing multi-oil core silica colloidosomes via salt-driven assembly of purely hydrophilic commercial nanoparticles dispersed within an oil-in-water-in-oil (O/W/O) double emulsion template. The internal structure and overall diameter of the capsules can be adjusted by altering the primary and secondary emulsification conditions. With this approach, 7-35 μm diameter multicore colloidosomes containing 0.9-4.2 μm large oil cores were produced. The capsules can easily be functionalized depending on the type of nanoparticles used in the preparation process. Here, metal oxide nanoparticles, such as Fe₃O₄, TiO₂, and ZnO, were successfully incorporated within the structure, conferring specific functional properties (i.e., magnetism and photocatalysis) to the final microcapsules. These capsules can also be ruptured by using ultrasound, enabling easy access to the internal core environments. Therefore, we believe this work offers a promising approach for producing multicore colloidosomes with adjustable structure and functionalities for the encapsulation of hydrophobic actives.