ZIF-8 coated gold nanospheres: A multi-responsive drug delivery system promoting the killing effect of photothermal therapy against osteosarcoma cells

Photothermal therapy(PTT)has been widely used in the treatment of tumors,but its efficacy is greatly limited by the inability of precise drug delivery and the increase of heat shock proteins(HSPs)caused by high temperature.This article describes a therapeutic strategy to enhance PTT with starvation therapy in conjunction with ferroptosis mechanism.A nanoparticle platform ZIF-8@GA was constructed by wrapping together glucose oxidase(GOX)and gold nanospheres(AuNPs)loaded with dihydroartemisinin(DHA)with zeolitic imidazolate framework-8(ZIF-8).This platform can take advantage of the micro-environment of osteosarcoma(OS)cells,featuring low pH and high reactive oxygen species(ROS),for precision drug delivery.GOX can effectively catalyze glucose to produce gluconic acid and H_(2)O_(2),and DHA can also induce ROS production in OS cells.ROS produced by GOX and DHA can further generate lipid peroxidation(LPO)and lead to ferroptosis of OS cells.At the same time,ROS and LPO produced can inhibit the expression of HSPs,thereby increasing the therapeutic effect of PTT.In vitro experiments show that the nanoparticles are pH and ROS responsive.1μg/mL GOX combined with 0.2μg/mL DHA promotes ferroptosis of OS cells,and increases the killing effect of near-infrared(NIR)on OS cells.Further in vivo experiments showed that the nano drug-delivery platform combined with PTT can effectively inhibit the growth of OS cells.Meanwhile,this study provides a new idea for the treatment of OS with biomaterials combined with various treatment methods.

Fano resonances in heterogeneous dimers of silicon and gold nanospheres

We theoretically investigate the optical properties of dimers consisting of a gold nanosphere and a silicon nanosphere. The absorption spectrum of the gold sphere in the dimer can be significantly altered and exhibits a pronounced Fano profile. Analytical Mie theory and numerical simulations show that the Fano profile is induced by constructive and destructive interference between the incident electric field and the electric field of the magnetic dipole mode of the silicon sphere in a narrow wavelength range. The effects of the silicon sphere size, distance between the two spheres, and excitation configuration on the optical responses of the dimers are studied. Our study reveals the coherent feature of the electric fields of magnetic dipole modes in dielectric nanostructures and the strong interactions of the coherent fields with other nanophotonic structures.

Hierarchical Nanogold Labels to Improve the Sensitivity of Lateral Flow Immunoassay

Lateral flow immunoassay(LFIA) is a widely used express method and offers advantages such as a short analysis time, simplicity of testing and result evaluation.However, an LFIA based on gold nanospheres lacks the desired sensitivity, thereby limiting its wide applications.In this study, spherical nanogold labels along with new types of nanogold labels such as gold nanopopcorns and nanostars were prepared, characterized, and applied for LFIA of model protein antigen procalcitonin. It was found that the label with a structure close to spherical provided more uniform distribution of specific antibodies on its surface, indicative of its suitability for this type of analysis.LFIA using gold nanopopcorns as a label allowed procalcitonin detection over a linear range of 0.5–10 ng mL^(-1) with the limit of detection of 0.1 ng mL^(-1), which was fivefold higher than the sensitivity of the assay with gold nanospheres. Another approach to improve the sensitivity of the assay included the silver enhancement method,which was used to compare the amplification of LFIA for procalcitonin detection. The sensitivity of procalcitonin determination by this method was 10 times better the sensitivity of the conventional LFIA with gold nanosphere as a label. The proposed approach of LFIA based on gold nanopopcorns improved the detection sensitivity without additional steps and prevented the increased consumption of specific reagents(antibodies).

Electrochemical biosensor employing PbS colloidal quantum dots/Au nanospheres-modified electrode for ultrasensitive glucose detection

Rapid and accurate detection of glucose is of great significance for diabetic management.Highly sensitive glucose sensors promise to achieve noninvasive detection technology,enabling more convenient and efficient means for large-scale screening and long-term dynamic monitoring of diabetes patients.In this work,we demonstrate a sensitive glucose electrochemical biosensor through the synergetic labelling strategy utilizing PbS colloidal quantum dots(CQDs)and Au nanospheres(AuNSs).The PbS CQDs/AuNSs/glucose oxidase(GOx)mixture could be stably immobilized on the carbon electrode surface via the onestep dip-coating method.The electrochemical biosensor employing PbS CQDs/AuNSs/GOx-modified electrode integrates the functions of specific molecule recognition,signal transduction as well as signal amplification.The sensor is capable of transducing the glucose enzyme-catalyzed reaction into significant current signals,exhibiting a good linear response in the glucose concentration range of 0.1μM-10 mM with the limit of detection being 1.432 nM.

An in vivo study of the biodistribution of gold nanoparticles after intervaginal space injection in the tarsal tunnel

The biodistribution of gold nanoparticles （AuNPs） is closely related to toxicological effects and is of great concern because of their potential application in diverse biomedical areas. However, with the discovery of novel anatomic and histological structures for fluid transport, the underlying mechanisms involved in the in vivo transport and biodistribution of AuNPs require further in-depth investigations. In the current study, we investigated the biodistribution of 10-nm AuNPs in rats after intervaginal space injection （ISI） in the tarsal tunnel, where a focal point of tendons, vessels, and nerve fibers may optimally connect to other remote connective tissues. The intravenous injection （IVI） of AuNPs served as a control. The blood and organs were collected at 5, 15, and 30 min and at 1, 4, 12, and 24 h after injection for quantitative analysis of Au distribution with inductively coupled plasma mass spectrometry （ICP-MS）. IVI and ISI yielded significantly different results： The AuNP content in the blood after ISI was much lower than that after IVI; was similar in the lungs, heart, and intestines; and was higher in the skin and muscle. These findings were supported by the ratios of AuNP content and relative organ AuNP distribution proportions. Our results demonstrated a fast, direct, and the circulation-independent AuNP-organ transport pathway, which may improve our understanding of physiological and pathological biodistribution processes in biological systems. Furthermore, these results provide novel insights into the in vivo transport and biodistribution of AuNPs, which may lead to novel and efficient therapeutic and administration strategies.