Light-activated doxorubicin-encapsulated perfluorocarbon nanodroplets for on-demand drug delivery in an in vitro angiogenesis model: Comparison between perfluoropentane and perfluorohexane

TME-Responsive Nanoplatform with Glutathione Depletion for Enhanced Tumor-Specific Mild Photothermal/Gene/Ferroptosis Synergistic Therapy

Background

Triple negative breast cancer (TNBC) is one of the worst prognosis types of breast cancer that urgently needs effective therapy methods. However, cancer is a complicated disease that usually requires multiple treatment modalities.

Methods

A tumor microenvironment (TME)-responsive PFC/TRIM37@Fe-TA@HA (abbreviated as PTFTH) nanoplatform was constructed by coating Fe3+ and tannic acid (TA) on the surface of TRIM37-siRNA loaded phase-transition perfluorocarbon (PFC) nanodroplets and further modifying them with hyaluronic acid (HA) to achieve tumor-specific mild photothermal/gene/ferroptosis synergistic therapy (MPTT/GT/ Ferroptosis) in vitro. Once internalized into tumor cells through CD44 receptor-mediated active targeting, the HA shell of PTFTH would be preliminarily disassembled by hyaluronidase (HAase) to expose the Fe-TA metal-phenolic networks (MPNs), which would further degrade in response to an acidic lysosomal environment, leading to HAase/pH dual-responsive release of Fe3+ and PFC/TRIM37.

Results

PTFTH showed good biocompatibility in vitro. On the one hand, the released Fe3+ could deplete the overexpressed glutathione (GSH) through redox reactions and produce Fe2+, which in turn converts endogenous H2O2 into highly cytotoxic hydroxyl radicals (•OH) for chemodynamic therapy (CDT). On the other hand, the local hyperthermia generated by PTFTH under 808 nm laser irradiation could not only improve CDT efficacy through accelerating the Fe2+-mediated Fenton reaction, but also enhance TRIM37-siRNA delivery for gene therapy (GT). The consumption of GSH and accumulation of •OH synergistically augmented intracellular oxidative stress, resulting in substantial tumor cell ferroptosis. Moreover, PTFTH possessed outstanding contrast enhanced ultrasound (CEUS), photoacoustic imaging (PAI) and magnetic resonance imaging (MRI) ability.

Conclusion

This PTFTH based multiple-mode therapeutic strategy has successfully achieved a synergistic anticancer effect in vitro and has the potential to be translated into clinical application for tumor therapy in future.

Ultrasound-responsive gallium protoporphyrin and oxygen loaded perfluoropentane nanodroplets for effective sonodynamic therapy of implant infections

Implant infections are severe complications in clinical treatment, which often accompany the formation of bacterial biofilms with high antibiotic resistance. Sonodynamic therapy (SDT) is an antibiotic-free method that can generate reactive oxygen species (ROS) to kill bacteria under ultrasound (US) treatment. However, the extracellular polymeric substances (EPS) barrier of bacterial biofilms and the hypoxic microenvironment significantly limit the antibiofilm activity of SDT. In this study, lipid-shelled perfluoropentane (PFP) nanodroplets loaded with gallium protoporphyrin IX (GaPPIX) and oxygen (O2) (LPGO NDs) were developed for the treatment of implant infections. Under US stimulation, LPGO NDs undergo the cavitation effect and disrupt the biofilm structure like bombs due to liquid-gas phase transition. Meanwhile, the LPGO NDs release O2 and GaPPIX upon US stimulation. The released O2 can alleviate the hypoxic microenvironment in the biofilm and enhance the ROS formation by GaPPIX for enhanced bacterial killing. In vivo experimental results demonstrate that the LPGO NDs can efficiently treat implant infections of methicillin-resistant Staphylococcus aureus (MRSA) in a mouse model by disrupting the biofilm structure, alleviating hypoxia, and enhancing bacterial killing by SDT. Therefore, this work provides a new multifunctional sonosensitizer to overcome the limitations of SDT for treating implant infections.

Nanodroplet-Based Super-Resolution Ultrasound Localization Microscopy

Over the past decade, super-resolution ultrasound localization microscopy (SR-ULM) has revolutionized ultrasound imaging with its capability to resolve the microvascular structures below the ultrasound diffraction limit. The introduction of this imaging technique enables the visualization, quantification, and characterization of tissue microvasculature. The early implementations of SR-ULM utilize microbubbles (MBs) that require a long image acquisition time due to the requirement of capturing sparsely isolated microbubble signals. The next-generation SR-ULM employs nanodroplets that have the potential to significantly reduce the image acquisition time without sacrificing the resolution. This review discusses various nanodroplet-based ultrasound localization microscopy techniques and their corresponding imaging mechanisms. A summary is given on the preclinical applications of SR-ULM with nanodroplets, and the challenges in the clinical translation of nanodroplet-based SR-ULM are presented while discussing the future perspectives. In conclusion, ultrasound localization microscopy is a promising microvasculature imaging technology that can provide new diagnostic and prognostic information for a wide range of pathologies, such as cancer, heart conditions, and autoimmune diseases, and enable personalized treatment monitoring at a microlevel.

Dual-drug loaded ultrasound-responsive nanodroplets for on-demand combination chemotherapy

Phase-changing nanodroplets are nanometric sized constructs that can be vaporized via external stimuli, such as focused ultrasound, to generate gaseous bubbles that are visible in ultrasound. Their activation can also be leveraged to release their payload, creating a method for ultrasound-modulated localized drug delivery. Here, we develop a perfluoropentane core nanodroplet that can simultaneously load paclitaxel and doxorubicin, and release them in response to an acoustic trigger. A double emulsion method is used to incorporate the two drugs with different physio-chemical properties, which allows for a combinatorial chemotherapy regimen to be used. Their loading, release, and biological effects on a triple negative breast cancer mouse model are investigated. We show that activation enhances the drug-delivery effect and delays the tumor growth rate in vivo. Overall, the phase-changing nanodroplets are a useful platform to allow on-demand delivery of combinations of drugs.

Ultrasound-guided chemoradiotherapy of breast cancer using smart methotrexate-loaded perfluorohexane nanodroplets

Chemoradiotherapy with controlled-release nanocarriers such as sono-sensitive nanodroplets (NDs) can enhance the anticancer activity of chemotherapy medicines and reduces normal tissue side effects. In this study, folic acid-functionalized methotrexate-loaded perfluorohexane NDs with alginate shell (FA-MTX/PFH@alginate NDs) were synthesized, characterized, and their potential for ultrasound-guided chemoradiotherapy of breast cancer was investigated in vitro and in vivo. The cancer cell (4T1) viabilities and surviving fractions after NDs and ultrasound treatments were significantly decreased. However, this reduction was much more significant for ultrasound in combination with X-ray irradiation. The in vitro and in vivo results confirmed that MTX-loaded NDs are highly biocompatible and they have no significant hemolytic activity and organ toxicity. Furthermore, the in vivo results indicated that the FA-MTX/PFH@alginate NDs were accumulated selectively in the tumor region. In conclusion, FA-functionalized MTX/PFH@alginate NDs have a great theranostic performance for ultrasound-controlled drug delivery in combination with radiotherapy of breast cancer.

Alleviation of cardiac fibrosis using acellular peritoneal matrix-loaded pirfenidone nanodroplets after myocardial infarction in rats

Myocardial fibrosis (MF) in the remote myocardium is a feature at the micoscopic level of pathological remodeling after myocardial infarction (MI). Although pirfenidone (PFD), an antifibrotic agent, is commonly used to inhibit fibrosis in multiple organs, its clinical use is limited because of the high doses required for favorable therapeutic outcomes and various side effects. Nanodrug technology has allowed for delayed quantitative drug release and reduced the amount of medication required, improving the treatment strategy for MF. In this study, we investigated the possible therapeutic effect of peritoneal matrix-loaded pirfenidone nanodroplets (NDs) on MI fibrosis. The results showed that the Perfluoropentane-Pirfenidone@Nanodroplets-Polyethylene glycol 2000 (PFP-PFD@NDs-PEG) described in this study was successfully synthesized and demonstrated a high potential for the targeted treatment of MI. The total duration of pirfenidone release from PFP-PFD@NDs-PEG was increased by loading it into an acellular peritoneal matrix (APM). Additionally, pirfenidone inhibited the transformation of cardiac fibroblasts into cardiac myofibroblasts in vitro and reduced the synthesis and secretion of collagen I and collagen III by cardiac myofibroblasts. The combination of the APM with pirfenidone nanodroplets achieved a slow drug release and showed excellent therapeutic effects on fibrosis in MI rats. Our study confirmed the feasibility and synergistic effectiveness of the APM combined with pirfenidone nanodroplets in the treatment of fibrosis in MI rats. Moreover, our technique offers a great potential for applying nanomedicine in other biomedical fields.

Tuning the Interfacial Properties of Fluorous Colloids Toward Ultrasound Programmable Bioactivity

Liquid-in-liquid emulsions are kinetically stable colloids that undergo liquid-to-gas phase transitions in response to thermal or acoustic stimuli. Perfluorocarbons (PFCs) are preferred species as their highly fluorinated nature imparts unique properties that are unparalleled by nonfluorinated counterparts. However, traditional methods to prepare PFC emulsions lack the ability to precisely tune the thermodynamic stability of the fluorous-water interphase and consequently control their vaporization behavior. Here, we report a privileged fluoroalkanoic acid that undergoes concentration-dependent assembly on the surfaces of fluorous droplets to modulate interfacial tension. This allows for the rational formulation of orthogonal PFC droplets that can be programmed to vaporize at specified ultrasound powers. We exploit this behavior in two exemplary biomedical settings by developing emulsions that aid ultrasound-mediated hemostasis and enable bioorthogonal delivery of molecular sensors to mammalian cells. Mechanistic insights gained from these studies can be generalized to tune the thermodynamic interfacial equilibria of PFC emulsions toward designing controllable tools for precision medicine.

Plasmonic carriers responsive to pulsed laser irradiation: a review of mechanisms, design, and applications

This review focuses on interactions which govern release from plasmonic carrier systems including liposomes, polymersomes, and nanodroplets under pulsed irradiation.

Effect of Laser Irradiation on Reversibility and Drug Release of Light-Activatable Drug-Encapsulated Liposomes

Although several studies have demonstrated repetitive drug release using light-activatable liposomes, inconsistent drug release at each activation limits widespread usage. Here, we report reversible plasmonic material-coated encapsulated liposomes for proportional controlled delivery of methotrexate (MTX), which is a common drug for cancer and autoimmune diseases, using repetitive laser irradiation. Our results suggest a proportional increase in total drug release after repetitive laser irradiation. We hypothesize that the drug is released via "melted" lipid bilayers when the plasmonic materials on the liposome surface are heated by laser irradiation followed by reversible formation of the liposome. To evaluate our hypothesis, the number density of liposomes after laser irradiation was measured using single-particle (liposome) collision experiments at an ultramicroelectrode. Collisional frequency data suggest that the number density of liposomes remains unaltered even after 60 s of laser irradiation at 1.1 and 1.8 W, indicating that the liposome structure is reversible. The results were further compared with gold nanorod-coated nanodroplets where drug is released via irreversible phase transition. In contrast to what was observed with the liposome particles, the number density of the nanodroplets decreased with increasing laser irradiation duration. The structure reversibility of our liposome particles may be responsible for repetitive drug release with laser heating. We also studied the temperature rise in the lipid bilayer by incorporating polymerized 10,12-pentacosadiynoic acid (PCDA) in the lipid composition. The red shift in the UV-vis spectrum due to the structural change in PCDA lipids after laser irradiation indicates a rise in temperature above 75 °C, which is also above the chain-melting temperature of the main lipid used in the liposomes. All these results indicate that drug is released from the light-activatable liposomes due to reversible nanostructural alteration in the lipid bilayer by plasmonic resonance heating. The liposomes have potential to be a drug carrier for dose-controlled repetitive drug delivery.