A review of recent advances in the use of complex metal nanostructures for biomedical applications from diagnosis to treatment.

Complex metal nanostructures represent an exceptional category of materials characterized by distinct morphologies and physicochemical properties. Nanostructures with shape anisotropies, such as nanorods, nanostars, nanocages, and nanoprisms, are particularly appealing due to their tunable surface plasmon resonances, controllable surface chemistries, and effective targeting capabilities. These complex nanostructures can absorb light in the near-infrared, enabling noteworthy applications in nanomedicine, molecular imaging, and biology. The engineering of targeting abilities through surface modifications involving ligands, antibodies, peptides, and other agents potentiates their effects. Recent years have witnessed the development of innovative structures with diverse compositions, expanding their applications in biomedicine. These applications encompass targeted imaging, surface-enhanced Raman spectroscopy, near-infrared II imaging, catalytic therapy, photothermal therapy, and cancer treatment. This review seeks to provide the nanomedicine community with a thorough and informative overview of the evolving landscape of complex metal nanoparticle research, with a specific emphasis on their roles in imaging, cancer therapy, infectious diseases, and biofilm treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Diagnostic Nanodevices.

A Biodegradable "One-For-All" Nanoparticle for Multimodality Imaging and Enhanced Photothermal Treatment of Breast Cancer.

Silver sulfide nanoparticles (Ag2S-NP) hold promise for various optical-based biomedical applications, such as near-infrared fluorescence (NIRF) imaging, photoacoustics (PA), and photothermal therapy (PTT). However, their NIR absorbance is relatively low, and previous formulations are synthesized using toxic precursors under harsh conditions and are not effectively cleared due to their large size. Herein, sub-5 nm Ag2S-NP are synthesized and encapsulated in biodegradable, polymeric nanoparticles (AgPCPP). All syntheses are conducted using biocompatible, aqueous reagents under ambient conditions. The encapsulation of Ag2S-NP in polymeric nanospheres greatly increases their NIR absorbance, resulting in enhanced optical imaging and PTT effects. AgPCPP nanoparticles exhibit potent contrast properties suitable for PA and NIRF imaging, as well as for computed tomography (CT). Furthermore, AgPCPP nanoparticles readily improve the conspicuity of breast tumors in vivo. Under NIR laser irradiation, AgPCPP nanoparticles significantly reduce breast tumor growth, leading to prolonged survival compared to free Ag2S-NP. Over time, AgPCPP retention in tissues gradually decreases, without any signs of acute toxicity, providing strong evidence of their safety and biodegradability. Therefore, AgPCPP may serve as a "one-for-all" theranostic agent that degrades into small components for excretion after fulfilling diagnostic and therapeutic tasks, offering good prospects for clinical translation.

A biodegradable "one-for-all" nanoparticle for multimodality imaging and enhanced photothermal treatment of breast cancer.

Silver sulfide nanoparticles (Ag 2 S-NP) have been proposed for various optical-based biomedical applications, such as near-infrared fluorescence (NIRF) imaging, photoacoustics (PA) and photothermal therapy (PTT). However, their absorbance is relatively low in the NIR window used in these applications, and previous formulations were synthesized using toxic precursors under harsh conditions and have clearance issues due to their large size. Herein, we synthesized sub-5 nm Ag 2 S-NP and encapsulated them in biodegradable, polymeric nanoparticles (AgPCPP). All syntheses were conducted using biocompatible reagents in the aqueous phase and under ambient conditions. We found that the encapsulation of Ag 2 S-NP in polymeric nanospheres greatly increases their NIR absorbance, resulting in enhanced optical imaging and photothermal heating effects. We therefore found that AgPCPP have potent contrast properties for PA and NIRF imaging, as well as for computed tomography (CT). We demonstrated the applicability of AgPCPP nanoparticles as a multimodal imaging probe that readily improves the conspicuity of breast tumors in vivo . PTT was performed using AgPCPP with NIR laser irradiation, which led to significant reduction in breast tumor growth and prolonged survival compared to free Ag 2 S-NP. Lastly, we observed a gradual decrease in AgPCPP retention in tissues over time with no signs of acute toxicity, thus providing strong evidence of safety and biodegradability. Therefore, AgPCPP may serve as a "one-for-all" theranostic agent that degrades into small components for excretion once the diagnostic and therapeutic tasks are fulfilled, thus providing good prospects for translation to clinical use.

Towards the Clinical Translation of a Silver Sulfide Nanoparticle Contrast Agent: Large Scale Production with a Highly Parallelized Microfluidic Chip.

Ultrasmall silver sulfide nanoparticles (Ag 2 S-NP) have been identified as promising contrast agents for a number of modalities and in particular for dual-energy mammography. These Ag 2 S-NP have demonstrated marked advantages over clinically available agents with the ability to generate higher contrast with high biocompatibility. However, current synthesis methods are low-throughput and highly time-intensive, limiting the possibility of large animal studies or eventual clinical use of this potential imaging agent. We herein report the use of a scalable silicon microfluidic system (SSMS) for the large-scale synthesis of Ag 2 S-NP. Using SSMS chips with 1 channel, 10 parallelized channels, and 256 parallelized channels, we determined that the Ag 2 S-NP produced were of similar quality as measured by core size, concentration, UV-visible spectrometry, and in vitro contrast generation. Moreover, by combining parallelized chips with increasing reagent concentration, we were able to increase output by an overall factor of 3,400. We also found that in vivo imaging contrast generation was consistent across synthesis methods and confirmed renal clearance of the ultrasmall nanoparticles. Finally, we found best-in-class clearance of the Ag 2 S-NP occurred within 24 hours. These studies have identified a promising method for the large-scale production of Ag 2 S-NP, paving the way for eventual clinical translation.

Effect of Nanoparticle Synthetic Conditions on Ligand Coating Integrity and Subsequent Nano-Biointeractions.

Most current nanoparticle formulations have relatively low clearance efficiency, which may hamper their likelihood for clinical translation. Herein, we sought to compare the clearance and cellular distribution profiles between sub-5 nm, renally-excretable silver sulfide nanoparticles (Ag2S-NPs) synthesized via either a bulk, high temperature, or a microfluidic, room temperature approach. We found that the thermolysis approach led to significant ligand degradation, but the surface coating shell was unaffected by the microfluidic synthesis. We demonstrated that the clearance was improved for Ag2S-NPs with intact ligands, with less uptake in the liver. Moreover, differential distribution in hepatic cells was observed, where Ag2S-NPs with degraded coatings tend to accumulate in Kupffer cells and those with intact coatings are more frequently found in hepatocytes. Therefore, understanding the impact of synthetic processes on ligand integrity and subsequent nano-biointeractions will aid in designing nanoparticle platforms with enhanced clearance and desired distribution profiles.

Development of a bio-MEMS device for electrical and mechanical conditioning and characterization of cell sheets for myocardial repair.

Here we propose a bio-MEMS device designed to evaluate contractile force and conduction velocity of cell sheets in response to mechanical and electrical stimulation of the cell source as it grows to form a cellular sheet. Moreover, the design allows for the incorporation of patient-specific data and cell sources. An optimized device would allow cell sheets to be cultured, characterized, and conditioned to be compatible with a specific patient's cardiac environment in vitro, before implantation. This design draws upon existing methods in the literature but makes an important advance by combining the mechanical and electrical stimulation into a single system for optimized cell sheet growth. The device has been designed to achieve cellular alignment, electrical stimulation, mechanical stimulation, conduction velocity readout, contraction force readout, and eventually cell sheet release. The platform is a set of comb electrical contacts consisting of three-dimensional walls made of polydimethylsiloxane and coated with electrically conductive metals on the tops of the walls. Not only do the walls serve as a method for stimulating cells that are attached to the top, but their geometry is tailored such that they are flexible enough to be bent by the cells and used to measure force. The platform can be stretched via a linear actuator setup, allowing for simultaneous electrical and mechanical stimulation that can be derived from patient-specific clinical data.