Development of light and pH-dual responsive self-quenching theranostic SPION to make EGFR overexpressing micro tumors glow and destroy.

Drug resistant and undetectable tumors easily escape treatment leading metastases and/or recurrence of the lethal disease. Therefore, it is vital to diagnose and destroy micro tumors using simple yet novel approaches. Here, we present fluorescence-based detection and light-based destruction of cancer cells that are known to be resistant to standard therapies. We developed a superparamagnetic iron oxide nanoparticle (SPION)-based theranostic agent that is composed of self-quenching light activated photosensitizer (BPD) and EGFR targeting ligand (Anti-EGFR ScFv or GE11 peptide). Photosensitizer (BPD) was immobilized to PEG-PEI modified SPION with acid-labile linker. Prior to stimulation of the theranostic system by light its accumulation within cancer cells is vital since BPD phototoxicity and fluorescence is activated by lysosomal proteolysis. As BPD is cleaved, the system switches from off to on position which triggers imaging and therapy. Targeting, therapeutic and diagnostic features of the theranostic system were evaluated in high and moderate level EGFR expressing pancreatic cancer cell lines. Our results indicate that the system distinguishes high and moderate EGFR expression levels and yields up to 4.3-fold increase in intracellular fluorescence intensity. Amplification of fluorescence signal was as low as 1.3-fold in the moderate or no EGFR expressing cell lines. Anti-EGFR ScFv targeted SPION caused nearly 2-fold higher cell death via apoptosis in high EGFR expressing Panc-1 cell line. The developed system, possessing advanced targeting, enhanced imaging and effective therapeutic features, is a promising candidate for multi-mode detection and destruction of residual drug-resistant cancer cells.

Stimuli-responsive theranostic system: A promising approach for augmented multimodal imaging and efficient drug release.

Destruction of drug resistant and invisible micro-tumors requires innovative screening and treatment modalities. Theranostic nanosystems offering multimodal imaging and therapy are attractive platforms with potential to make micro-tumors visible to clinicians. Gold nanoparticles (AuNPs) are intrinsic theranostic agents and act as fluorescence quenchers. They can be easily transformed to multimodal imaging and combination therapy agents by combining them with various adjuvant therapies such as photodynamic therapy. In this study, we developed a highly specific, hybrid theranostic agent that is only activated when it meets with its stimuli at the site of interest. Surface-coated AuNPs were modified with Cathepsin B cleavable peptide (stimuli responsive linker) and Verteporfin (photosensitizer and fluorescence imaging agent). Unless the theranostic system meets with the internal stimuli in tumor cells, fluorescence is quenched due to AuNP-Verteporfin and Verteporfin-Verteporfin interactions. Following cellular internalization of the theranostic agent, fluorescence is gained by Cathepsin B cleavage and phototoxicity is initiated by light. The system was efficiently internalized by SKOV-3 cells and demonstrated high specificity towards its stimuli. In comparison to Verteporfin, ∼14-fold fluorescence increase, 81% fluorescence recovery and comparable toxicity were achieved. The system is a promising candidate for multimodal imaging and dual treatment to destroy the micro-tumors.

A Rational design of multi-functional nanoplatform: Fluorescent-based "off-on" theranostic gold nanoparticles modified with D-α-Tocopherol succinate.

It is crucial to develop nanocarrier systems to detect and treat drug-resistant micro tumors to prevent recurrence and/or metastasis of cancer. Due to their exceptional features such as biocompatibility, easy surface modification, serving as imaging and therapeutic agent, gold nanoparticles (AuNPs) draw attention as theranostic agents. It is beneficial to combine AuNPs with a second imaging and/or treatment modality such as photodynamic therapy (PDT). PDT is a non-mutagenic treatment approach in which photosensitizer is activated with light, generating reactive oxygen species and/or free radicals to destroy tumor cells. With the aim of developing "off-on" theranostic system, citrate stabilized spherical 13 nm AuNPs were densely coated with polyethylene glycol (PEG). To advance the theranostic feature of PEGylated AuNPs, they were further functionalized with FDA-Approved photosensitizer, Verteporfin (BPD-MA). Due to static quenching between BPD-MA and AuNPs as well as in between nearby BPD-MA molecules, the fluorescence of the ground state complex is quenched and the system is in "off" state. When BPD-MA molecules are cleaved from the AuNPs surface and diffuse away, fluorescence is recovered. Consequently, the system switches to the "on" state. Among the various mole ratios of BPD-MA carrying conjugates prepared, the most promising candidate was selected based on stability, quenching factor, and fluorescence recovery rate. The conjugate was further decorated with D-α-Tocopherol succinate (VitES) to increase the therapeutic efficacy of the theranostic agent via enhancing cellular uptake. Our results showed that it was possible to achieve as high as 80 times fluorescence quenching when the system was "off". As the system switched from "off" to "on" state, 51% of the fluorescence was recovered. When BPD-MA was immobilized on the PEGylated AuNPs, the phototoxic effect of BPD-MA increased twice against the MCF-7 cell line. Moreover, the developed system showed four times more phototoxicity than BPD-MA alone after it was decorated with VitES. Since the developed system is capable of dual imaging (computed tomography and fluorescence) and dual treatment (PDT and hyperthermia), it potentially offers superior imaging and therapy options for various types of in vitro/in vivo applications.

Design of Dense Brush Conformation Bearing Gold Nanoparticles as Theranostic Agent for Cancer.

Dense brush conformation-bearing theranostic agents are emerging as drug delivery systems due to their higher ability to escape from reticuloendothelial system uptake which prolongs their in vivo circulation time. With the aim of developing dual therapy agent, 13-nm gold nanoparticles' (AuNPs) surfaces were coated with different amounts of polyethylene glycol (PEG) (SH-PEG-NH2) to obtain dense brush conformation-bearing theranostic agents. Among the 14 different theranostic agent candidates prepared, the one hosting 1819 PEG per particle was selected as the most promising theranostic agent candidate based on structural conformation, stability, size, zeta potential, hemocompatibility, cell inhibition, and cell death pathway towards MCF-7 cell line. To test drug delivery efficiency of the developed PEGylated AuNP and to improve efficacy of the treatment, apoptotic peptide (AP) was covalently conjugated to NH2 terminus of the PEG in various ratios to yield AuNP-AP conjugate. Among the prepared conjugates, the one having 1 nmol of peptide per milliliter of AuNP yielded the most promising results based on the same criteria as employed for PEGylated AuNPs. Besides, incorporation of AP to AuNP returned in superior efficacy of AP since it was possible to achieve 50% cell death with 1000 times less amount of AP alone.

Association between the growth arrest-specific 6 (Gas6) gene polymorphism c.834 + 7G>A and preeclampsia.

OBJECTIVE: Preeclampsia (PE) is a hypertensive disease of pregnancy complicating 2-8% of all pregnancies. The exact pathophysiology still remains unknown. Growth arrest-specific 6 (Gas6) is a member of the vitamin K-dependent protein family and it has been suggested as a novel atherothrombotic risk factor with anti-angiogenic and pro-atherogenic properties. The goal of the our study was to investigate the relationships between the c.834 + 7G > A polymorphism of GAS6, plasma Gas6 levels and PE. METHODS: A total of 150 women, including 82 preeclamptic pregnant women and 68 normotensive pregnant (NP) women, were recruited in the current study. Blood samples were taken from all participants. Plasma Gas6 levels measured by an enzyme-linked immunosorbent assay. GAS6 polymorphism was determined using a PCR-RFLP method. RESULTS: The plasma Gas6 levels of preeclamptic patients were significantly lower than those of NP women (8.65 ± 3.70 ng/ml and 10.89 ± 4.23 ng/ml respectively, p < 0.001). The GG genotype was the most prevalent, and the risk of PE was 3.5-fold higher in pregnant women with GG genotype compared to woman with AA genotype (p < 0.01). The A allele was less frequent in preeclamptic patients than in control subjects (OR = 2.118, 95% CI = 1.330-3.371, p < 0.001). CONCLUSIONS: Our results suggest that GAS6 c.834 + 7G > A polymorphism may have a pivotal role in the pathogenesis of PE suggesting that the A allele has a protective role for PE.