Modelling centrifugal membrane deployment of solar sails with the discrete element method

Spin-stabilized solar sails have been extensively studied in recent years. In this paper, a DEM-based approach is proposed for dynamic analysis of the centrifugal deployment of solar sails. In order to validate the proposed approach, the deployment of a small-scale solar sail similar to “IKAROS” is studied. The membrane is discretised into a number of particles, with no physical contact between them. Non-contact interaction is introduced to model in-plane stiffness of the membrane. In order to improve the accuracy, additional forces are applied to the mass particles to model buckling strength, crease stiffness, air drag and damping. The predicted results of the membrane deployment are compared with the experimental data and numerical results in the literature

Site-Specific 111In-Radiolabeling of Dual-PEGylated Porous Silicon Nanoparticles and Their In Vivo Evaluation in Murine 4T1 Breast Cancer Model

Polyethylene glycol (PEG) has been successfully used for improving circulation time of several nanomaterials but prolonging the circulation of porous silicon nanoparticles (PSi NPs) has remained challenging. Here, we report a site specific radiolabeling of dual-PEGylated thermally oxidized porous silicon (DPEG-TOPSi) NPs and investigation of influence of the PEGylation on blood circulation time of TOPSi NPs. Trans-cyclooctene conjugated DPEG-TOPSi NPs were radiolabeled through a click reaction with [111In]In-DOTA-PEG4-tetrazine (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and the particle behavior was evaluated in vivo in Balb/c mice bearing 4T1 murine breast cancer allografts. The dual-PEGylation significantly prolonged circulation of [111In]In-DPEG-TOPSi particles when compared to non-PEGylated control particles, yielding 10.8 ± 1.7% of the injected activity/g in blood at 15 min for [111In]In-DPEG-TOPSi NPs. The improved circulation time will be beneficial for the accumulation of targeted DPEG-TOPSi to tumors

Site-Specific 111In-Radiolabeling of Dual-PEGylated Porous Silicon Nanoparticles and Their In Vivo Evaluation in Murine 4T1 Breast Cancer Model

Polyethylene glycol (PEG) has been successfully used for improving circulation time of several nanomaterials but prolonging the circulation of porous silicon nanoparticles (PSi NPs) has remained challenging. Here, we report a site specific radiolabeling of dual-PEGylated thermally oxidized porous silicon (DPEG-TOPSi) NPs and investigation of influence of the PEGylation on blood circulation time of TOPSi NPs. Trans-cyclooctene conjugated DPEG-TOPSi NPs were radiolabeled through a click reaction with [111In]In-DOTA-PEG4-tetrazine (DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) and the particle behavior was evaluated in vivo in Balb/c mice bearing 4T1 murine breast cancer allografts. The dual-PEGylation significantly prolonged circulation of [111In]In-DPEG-TOPSi particles when compared to non-PEGylated control particles, yielding 10.8 ± 1.7% of the injected activity/g in blood at 15 min for [111In]In-DPEG-TOPSi NPs. The improved circulation time will be beneficial for the accumulation of targeted DPEG-TOPSi to tumors

Black porous silicon as a photothermal agent and immunoadjuvant for efficient antitumor immunotherapy

Photothermal therapy (PTT) in combination with other treatment modalities has shown great potential to activate immunotherapy against tumor metastasis. However, the nanoparticles (NPs) that generate PTT have served as the photothermal agent only. Moreover, researchers have widely utilized highly immuno-genic tumor models to evaluate the immune response of these NPs thus giving over-optimistic results. In the present study black porous silicon (BPSi) NPs were developed to serve as both the photothermal agent and the adjuvant for PTT-based antitumor immunotherapy. We found that the poorly immunogenic tumor models such as B16 are more valid to evaluate NP-based immunotherapy than the widely used im-munogenic models such as CT26. Based on the B16 cancer model, a cocktail regimen was developed that combined BPSi-based PTT with doxorubicin (DOX) and cytosine-phosphate-guanosine (CpG). BPSi-based PTT was an important trigger to activate the specific immunotherapy to inhibit tumor growth by featuring the selective upregulation of TNF-alpha. Either by adding a low dose DOX or by prolonging the laser heating time, a similar efficacy of immunotherapy was evoked to inhibit tumor growth. Moreover, BPSi acted as a co-adjuvant for CpG to significantly boost the immunotherapy. The present study demonstrates that the BPSi-based regimen is a potent and safe antitumor immunotherapy modality. Moreover, our study high-lighted that tuning the laser heating parameters of PTT is an alternative to the toxic cytostatic to evoke immunotherapy, paving the way to optimize the PTT-based combination therapy for enhanced efficacy and decreased side effects.Peer reviewe

Systematic design of cell membrane coating to improve tumor targeting of nanoparticles

Cell membrane (CM) coating technology is increasingly being applied in nanomedicine, but the entire coating procedure including adsorption, rupture, and fusion is not completely understood. Previously, we showed that the majority of biomimetic nanoparticles (NPs) were only partially coated, but the mechanism underlying this partial coating remains unclear, which hinders the further improvement of the coating technique. Here, we show that partial coating is an intermediate state due to the adsorption of CM fragments or CM vesicles, the latter of which could eventually be ruptured under external force. Such partial coating is difficult to self-repair to achieve full coating due to the limited membrane fluidity. Building on our understanding of the detailed coating process, we develop a general approach for fixing the partial CM coating: external phospholipid is introduced as a helper to increase CM fluidity, promoting the final fusion of lipid patches. The NPs coated with this approach have a high ratio of full coating (similar to 23%) and exhibit enhanced tumor targeting ability in comparison to the NPs coated traditionally (full coating ratio of similar to 6%). Our results provide a mechanistic basis for fixing partial CM coating towards enhancing tumor accumulation.Peer reviewe