Photothermal Conversion Profiling of Large-Scaled Synthesized Gold Nanorods Using Binary Surfactant with Hydroquinone as a Reducing Agent

Codelivery of CuS and DOX into Deep Tumors with Size and Charge-Switchable PAMAM Dendrimers for Chemo-photothermal Therapy

Accurate targeting of therapeutic agents to specific tumor tissues, especially via deep tumor penetration, has been an effective strategy in cancer treatments. Here, we described a flexible nanoplatform, pH-responsive zwitterionic acylsulfonamide betaine-functionalized fourth-generation PAMAM dendrimers (G4-AB), which presented multiple advantages for chemo-photothermal therapy, including template synthesis of ultrasmall copper sulfide (CuS) nanoparticles and further encapsulation of doxorubicin (DOX) (G4-AB-DOX/CuS), long-circulating performance by a relatively large size and zwitterionic surface in a physiological environment, combined size shrinkage, and charge conversions via pH-responsive behavior in an acidic tumor microenvironment (TME). Accordingly, high tumor penetration and positive cell uptake for CuS and DOX have been determined, which triggered an excellent combination treatment under near-infrared irradiation in comparison to the monochemotherapy system and irresponsive chemo-photothermal system. Our study represented great promise in constructing multifunctional carriers for the effective delivery of photothermal nanoparticles and drugs in chemo-photothermal therapy.

Porphyrin as a Cryoprotectant for Graphene Oxide-Coated Gold Nanorods to Produce Conjugated Product with Improved Stability and Opto-Phototherapeutic Properties

Graphene oxide (GO) as a coating material for gold nanorods (AuNRs) has gained interest in reducing toxicity and improving the photothermal profiling of AuNRs. However, there is still a challenge regarding the storage of colloidal suspensions of GO-coated AuNRs (GO@AuNRs). Hence, the conjugation of GO@AuNRs to meso-tetra-(4-sulfonatophenyl)porphyrin (TPPS4), an anionic water-soluble porphyrin, has been reported to enhance their re-dispensability and improve their phototherapeutic properties. The AuNRs and GO were synthesised using seed-mediated and Hummers' methods, respectively. The GO@AuNRs were conjugated to TPPS4 and characterised using ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy, zeta analyser, dynamic light scattering (DLS), photoluminescence spectroscopy (PL), x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and Fourier-transform infrared spectroscopy (FTIR) before freeze-drying. The results showed that the AuNRs were sandwiched between GO and TPPS4. After freeze-drying, the freeze-dried conjugate was dispensed in deionised water without adding cryoprotectants and its properties were compared to those of the unfreeze-dried conjugate. The results showed that the freeze-dried conjugate contained similar optical properties to the unfreeze-dried conjugate. However, the bare GO@AuNRs showed a change in the optical properties after freeze-drying. These results revealed that porphyrin is an excellent additive to reduce the freeze-drying stress tolerance of GO@AuNRs. The freeze-dried conjugate also showed both singlet oxygen and photothermal properties of GO@AuNRs and porphyrin. These results indicated that the freeze-dried conjugate is a promising dual photodynamic and photothermal agent, and porphyrin can act as a cryoprotectant.

CuS-131I-PEG Nanotheranostics-Induced "Multiple Mild-Hyperthermia" Strategy to Overcome Radio-Resistance in Lung Cancer Brachytherapy

Brachytherapy is one mainstay treatment for lung cancer. However, a great challenge in brachytherapy is radio-resistance, which is caused by severe hypoxia in solid tumors. In this research, we have developed a PEGylated ¹³¹I-labeled CuS nanotheranostics (CuS-¹³¹I-PEG)-induced "multiple mild-hyperthermia" strategy to reverse hypoxia-associated radio-resistance. Specifically, after being injected with CuS-¹³¹I-PEG nanotheranostics, tumors were irradiated by NIR laser to mildly increase tumor temperature (39~40 °C). This mild hyperthermia can improve oxygen levels and reduce expression of hypoxia-induced factor-1α (HIF-1α) inside tumors, which brings about alleviation of tumor hypoxia and reversion of hypoxia-induced radio-resistance. During the entire treatment, tumors are treated by photothermal brachytherapy three times, and meanwhile mild hyperthermia stimulation is conducted before each treatment of photothermal brachytherapy, which is defined as a "multiple mild-hyperthermia" strategy. Based on this strategy, tumors have been completely inhibited. Overall, our research presents a simple and effective "multiple mild-hyperthermia" strategy for reversing radio-resistance of lung cancer, achieving the combined photothermal brachytherapy.

Thermal and Medium Stability Study of Polyvidone-Modified Graphene Oxide-Coated Gold Nanorods with High Photothermal Efficiency

Coating gold nanorods (AuNRs) with different materials, such as polymers and graphene-based materials, has improved their biocompatibility. However, these materials have been shown to cause the instability of AuNRs in thermal and culture mediums. In addressing this issue, we herein report the synthesis, thermal and culture medium stability, and photothermal profiling of Polyvidone (PVP)-modified graphene oxide (GO)-coated AuNRs (mGO@AuNRs). The AuNRs, with a size of 40.70 nm × 9.16 nm and absorbing at 820 nm, were coated with PVP, GO, and mGO. The colloidal stability of the nanocomposites was tested in three commonly used cell culture mediums: the Roswell Park Memorial Institute 1640 (RPMI-1640), Dulbecco's Modified Eagle Medium, (DMEM) and Dulbecco's phosphate-buffered saline (PBS) using UV-Vis-NIR and dynamic light scattering. The GO-based nanocomposites were stable compared to PVP@AuNRs and AuNRs in all mediums. The photothermal profiling of mGO@AuNRs showed higher heat production, with the photothermal conversion efficiency of 54.8%, which is higher than the bare AuNRs, GO@AuNRs, and PVP@AuNRs. In addition, the mGO@AuNRs also showed good thermal stability at 70 °C for more than 24 h. These results present the dual coating of PVP and GO as excellent stabilising agents for AuNRs with good photothermal profiling.