Preparation And Application Of GE11-PDA-Pt@USPIOs Nano Formulations For Relief Of Tumor Hypoxia And MRI/PAI-Guided Tumor Chemoradiation Therapy

The overall incidence of malignant tumors is increasing year by year.Chemotherapy combined with radiotherapy is a clinically recognized method for cancer treatment.However,the low tumor accumulation of chemical drugs and their non-selective toxicity to healthy tissues,as well as the limited tolerance of normal tissues to radiation doses,make it difficult to meet clinical requirements for chemo-radiotherapy in some cases.Moreover,the tumor hypoxic microenvironment makes the tumor resistant to radiotherapy and chemotherapy.Therefore,it is urgent to explore new treatment paradigm for chemoradiation combination therapy,enhancing the therapeutic effect,while reducing the side effect.In this study,we developed a cisplatin-loaded,poly dopamine-coated and GE11 peptide-conjugated multi-functional theranostic system(GE11-PDA-Pt@USPIOs)based on poly acrylic acid coated ultra-small superparamagnetic iron oxide nanoparticles(PAA@USPIOs)for modulation of tumor hypoxic microenvironment and magnetic resonance imaging/photoacoustic imaging(MRI/PAI)guided chemo-radiation therapy of tumors.Moreover,three/two-valence iron ions,Fe3+ and Fe2+,could respectively demonstrate catalase-like and peroxidase-like activities under the acid condition.The dual enzyme-like feature of USPIOs are favourable for tumor therapy by directly damaging tumor cells with the toxic hydroxyl radicals or facilitating chemo-radiotherapy by relief of tumor hypoxic condition.PAA-coated USPIOs were provided by Professor Hongchen Gu.PAA@USPIOs was around 4.5 nm in diameter and uniform in size.PAA coating was dense and accounted for 58.26% of total weight.The thick PAA coating on USPIOs allowed highly efficient cisplatin loading by complexing carboxylic groups on PAA with cisplatin prodrug;a subsequent thin layer of poly dopamine(PDA)encapsulation following drug loading provided a means for further surface functionalization,imparted the particles photo-thermal property,but did not impede drug and iron ions release.Surface polyethylene glycol(PEG)modification was carried out to enhance biocompatibility and hydrophilicity,and the azidation module of GE11 peptide(YHWYGYTPQNVI)was constructed and coupled to the surface of USPIOs by "click" chemistry to prepare targeted nanoparticles GE11-PDA-Pt@USPIOs.Subsequently,the specificity,the improvement of tumor hyposia,biocompatibility and therapeutic effects of the probes were evaluated in vitro and in vivo.Nanoparticles that can target EGFR are constructed.High-efficiency loading of cisplatin is achieved.The nanoparticles coated with polydopamine have good photothermal properties,and do not impede the release of drugs and iron ions.The coupling efficiency of GE11 peptide is high(95%-97%);in vitro cell targeting experiments show that GE11-PDA-Pt@USPIO nanoparticles is highly specific to EGFR tumor cells,GE11-PDAPt@USPIO nanoparticles can effectively catalyze the decomposition of H2O2 into oxygen and improve the hypoxic environment of tumor.Moreover,GE11-PDA-Pt@USPIO nanoparticles can effectively inhibit the growth of tumor cells.The inhibitory effect of radiotherapy combined with chemotherapy is more obvious,showing good cell therapy effect;the use of nanoparticles for in vivo MRI and PA imaging showed that the targeted nanoparticles could specifically target the tumor and rapidly aggregate in the tumor area,immunohistochemical results of tumors confirmed that H1299 cancer cells were highly expressed in EGFR,and Prussian blue staining of tumor tissue also demonstrated the high concentration of nanoparticles in the tumor site.The results of photoacoustic imaging showed that the targeted iron oxide nanoparticles could catalyze the endogenous H2O2 of the tumor and effectively improve the hypoxic environment of the tumor.In vivo treatment showed that cisplatin has the effect of inhibiting tumor growth.Combined chemotherapy and radiotherapy can significantly inhibit tumor growth and prolong the survival,and H&E tissue staining results show that the probe has no damage to other organs.Our study for the first time illustrates USPIOs is able to relieve tumor hypoxia and GE11-PDA-Pt@USPIOs is highly effective for chemoradiation therapy of EGFR positive tumors.