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Immuno-specific enrichment of extracellular vesicles (EVs) originating from specific cells/tissues is a promising source of information towards improving insights into cellular pathways underpinning various pathologies and developing novel non-invasive diagnostic methods. Enrichment is an important aspect in mass spectrometry-based analyses of EVs. Herein, we report a protocol for immuno-magnetic enrichment of subtype specific EVs and their subsequent processing for mass spectrometry. Specifically, we conjugated placental alkaline phosphatase (PLAP) antibodies to magnetic iron oxide nanowires (NWs) derived from bacterial biofilms and demonstrated the utility of this approach by enriching placental specific EVs (containing PLAP) from cell culture media. We demonstrate efficient PLAP+ve EV enrichment for both NW-PLAP and Dynabeads™-PLAP, with PLAP protein recovery (83.7±8.9% and 83.2±5.9%, respectively), high particle-to-protein ratio (7.5±0.7×109 and 7.1 ± 1.2×109, respectively), and low non-specific binding of non-target EVs (7±3.2% and 5.4±2.2%, respectively). Furthermore, our optimized EV enrichment and processing approach identified 2518 and 2545 protein groups with mass spectrometry for NW-PLAP and Dynabead™-PLAP, respectively, with excellent reproducibility (Pearson correlation 0.986 and 0.988). The proposed immuno-specific EVs enrichment and liquid chromatography-tandem mass spectrometry method using naturally occurring iron oxide magnetic NWs or gold-standard Dynabeads™ enables high-quality EV proteomic studies.

Background Gastrectomy with extended (D2) lymphadenectomy is considered standard of care for gastric cancer to provide the best possible outcomes and pathologic staging. However, D2 gastrectomy is a technically demanding operation and reported to be associated with increased complications and mortality. Application of sentinel lymph node (SLN) concept in gastric cancer has the potential to reduce patient morbidity; however, SLN techniques are not established for gastrectomy, in part due to lack of practical tracers. An effective and convenient tracer with enhanced SLN accumulation is critically needed. Methods Mannose-labelled magnetic tracer ‘FerroTrace’ and fluorescent dye indocyanine green (ICG) were injected laparoscopically into the stomach submucosa of 8 healthy swine under general anaesthesia. Intraoperative fluorescence imaging was used to highlight draining lymphatic pathways containing ICG, while preoperative T2-weighted MRI and ex vivo magnetometer probe measurements were used to identify nodes containing FerroTrace. Lymphadenectomy was performed either robotically (n = 2) or via laparotomy (n = 6). Results Mixing ICG and FerroTrace ensured concurrence of fluorescent and magnetic signals in SLNs. An initial trial with robotic dissection removed all magnetic LNs (n = 4). In the subsequent laparotomy study that targeted all ICG-LNs based on intraoperative fluorescence imaging, dissection removed an average of 4.7 ± 1.2 fluorescent, and 2.0 ± 1.3 magnetic LNs per animal. Both MRI and magnetometer detected 100% of SLNs (n = 7). FerroTrace demonstrated high specificity to SLNs, which contained 76 ± 30% of total lymphotropic iron, and 88 ± 20 % of the overall magnetometer signal. Conclusions Through utilisation of this dual tracer approach, SLNs were identified via preoperative MRI, visualised intraoperatively with fluorescence imaging, and confirmed with a magnetometer. This combination pairs the sensitivity of ICG with SLN-specific FerroTrace and can be used for reliable SLN detection in gastric cancer, with potential applications in neoadjuvant therapy. Graphical abstract

Accurate and precise delineation of gross tumour volumes remains a barrier to radiotherapy dose escalation and boost dosing in the treatment of solid tumours, such as prostate cancer. Magnetic resonance imaging of tumour molecular targets has the power to enable focal dose boosting, particularly when combined with technological advances such as MRI-LINAC. Fibroblast activation protein (FAP) is a transmembrane protein overexpressed in stromal components of >90% of epithelial carcinomas. Herein we compare targeted MRI of gold standard PSMA with FAP in the delineation of orthotopic tumours in a mouse model of prostate cancer. Control (no ligand), FAP and PSMA-targeting iron oxide nanoparticles were prepared with modification of an MRI agent (FerroTrace). Mice with orthotopic LNCaP tumours underwent T2-weighted 3D MRI 24 hours after intravenous injection of contrast agents. FAP and PSMA nanoparticles produced contrast enhancement on MRI when compared to control nanoparticles, which was most pronounced on the tumour periphery. FAP-targeted MRI increased the proportion of tumour contrast enhancing black pixels by 13.37% when compared to PSMA. Furthermore, analysis of changes in R2 values between healthy prostates and LNCaP tumours indicated an increase in contrast enhancing pixels in the tumour border of 15%, when targeting FAP, in contrast to PSMA This study demonstrates preclinical feasibility of PSMA and FAP-targeted MRI which can enable targeted image-guided focal therapy of localized prostate cancer.

Background Sentinel lymph node biopsy (SLNB) is a staging procedure dependent on accurate mapping of draining lymphatics via tracers. Robot-assisted SLNB enables access to multiple neck levels with a single incision and intraoperative fluorescence guidance to the SLN. Methods Lymphatic mapping in swine was done using a magnetic tracer and fluorescent dye, injected into the tongue. MRI preoperatively mapped lymphatic spread of the magnetic tracer. Dissection was performed using a da Vinci Xi robot guided by fluorescence-imaging of the dye. Results Robot-assisted SLNB was successfully performed in all animals (n = 5). A novel MRI protocol differentiated SLNs (n = 6) from lower echelon nodes (n = 11) based on flow progression. Fluorescence imaging provided valuable intraoperative guidance and correlated with magnetic-positive nodes. Conclusions This study demonstrates preclinical feasibility of a robot-assisted approach to SLNB using magnetic and fluorescent tracers in the head and neck, enabling both preoperative mapping and intraoperative guidance. Refereed/Peer-reviewed

337 Background: Gastrectomy with extended (D2) lymphadenectomy is considered as a standard of care for gastric cancer to provide best possible outcomes and pathologic staging. However, D2 gastrectomy is technically demanding operation and reported to be associated with increased complications, including bleeding, pancreatitis, abscess, chylous ascites, and mortality. Application of sentinel lymph node mapping in gastric cancer has the potential to reduce patient morbidity, while facilitating detailed pathology processing required to accurately identify nodal metastases. However, sentinel lymph node biopsy techniques are not established for gastrectomy because of a lack of practical tracers; an effective and convenient tracer that exclusively accumulates in sentinel lymph nodes is critically needed. Methods: A lymphotropic tracer solution consisting of mannose-labelled magnetic nanoparticles (SPIONs) and a fluorescent dye (indocyanine green, ICG) was injected laparoscopically into the stomach submucosa of 6 healthy female domesticated pigs while under general anaesthesia. Intraoperative laparoscopic fluorescence imaging was used to highlight draining lymphatic pathways containing ICG, while a combination of T2-weighted MRI and magnetometer probe detection were used to identify nodes containing SPIONs. Results: Mixing the ICG dye and SPIONs ensured concurrence of fluorescent and magnetic signals in the sentinel nodes. Average tracer accumulation time before dissection was 5 hours. On average 4.5 fluorescent nodes (range 2–7) were removed, of which 2 (average) were also magnetic (range 1–4). Magnetic nodes could be identified using both preoperative MRI and intraoperative magnetometer probe. The mannose label of the SPIONs produced a strong binding affinity to macrophages, and in combination with particle size (80 nm) results in enhanced retention in the sentinel nodes. On average, after 5 hours accumulation time, the sentinel nodes contained 4.1% of the SPION injected dose and 88% of the magnetometer counts. Conclusions: Through the co-injection of fluorescent and mannose-labelled magnetic tracers, lymphatic drainage pathways can be determined preoperatively with MRI, visualised with intraoperative fluorescence cameras, and SLNs confirmed with magnetometer. Although ICG flows through multiple echelons, in doing so it creates a lymphatic roadmap to guide surgeons. The addition of magnetic particles provides sentinel node discrimination, so in combination, these two tracers could greatly enhance the capability to detect SLNs in gastric cancer.

Intermetallic (Ni-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of NiCl2.6H2O and SnCl2.2H2O at mass ratio and Ni:Sn = 45:55. The ratio is chosen in accordance with the Ni-Sn binary system phase diagram. A "template" technique which involves borohydride reduction of intermetallic nanoparticles on a support (carbon foam, graphite, carbon powder) is also used. The samples which are Ni-Sn alloys and carbon-based nanocomposites are studied by scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The samples are electrochemically tested as electrode materials in Li-ion batteries.

Intermetallic (Cu-Sn) nanoparticles are synthesized through a borohydride reduction with NaBH4 in a mixture of aqueous solutions of CuCl2.2H2O and SnCl2.2H2O at mass ratio Cu:Sn = 3:2 applying a template technique with a support such as carbon foam. The ratio is chosen in accordance with the Cu-Sn binary system phase diagram. The reductive precipitation is carried out at room temperature and atmospheric pressure. Porous nanocomposites are obtained and studied by scanning and transmission electron microscopy (SEM/TEM), and X-ray diffraction (XRD) analysis. The electrochemical behavior of the synthesized Cu-Sn alloy and the C-based composites (С-foam/Cu-Sn alloy) as positive electrodes is also investigated in a Li-ion battery) using a computer controlled laboratory cycling equipment BA500 Series Battery Analyzer.