Near-Infrared Light-Activated Pt@Au Nanorings-Based Probe for Fluorescence Imaging and Targeted Photothermal Therapy of Cancer Cells

Photothermal Nanomaterials: A Powerful Light-to-Heat Converter

All forms of energy follow the law of conservation of energy, by which they can be neither created nor destroyed. Light-to-heat conversion as a traditional yet constantly evolving means of converting light into thermal energy has been of enduring appeal to researchers and the public. With the continuous development of advanced nanotechnologies, a variety of photothermal nanomaterials have been endowed with excellent light harvesting and photothermal conversion capabilities for exploring fascinating and prospective applications. Herein we review the latest progresses on photothermal nanomaterials, with a focus on their underlying mechanisms as powerful light-to-heat converters. We present an extensive catalogue of nanostructured photothermal materials, including metallic/semiconductor structures, carbon materials, organic polymers, and two-dimensional materials. The proper material selection and rational structural design for improving the photothermal performance are then discussed. We also provide a representative overview of the latest techniques for probing photothermally generated heat at the nanoscale. We finally review the recent significant developments of photothermal applications and give a brief outlook on the current challenges and future directions of photothermal nanomaterials.

Gold Nanoparticles as a Biosensor for Cancer Biomarker Determination

Molecular biology applications based on gold nanotechnology have revolutionary impacts, especially in diagnosing and treating molecular and cellular levels. The combination of plasmonic resonance, biochemistry, and optoelectronic engineering has increased the detection of molecules and the possibility of atoms. These advantages have brought medical research to the cellular level for application potential. Many research groups are working towards this. The superior analytical properties of gold nanoparticles can not only be used as an effective drug screening instrument for gene sequencing in new drug development but also as an essential tool for detecting physiological functions, such as blood glucose, antigen-antibody analysis, etc. The review introduces the principles of biomedical sensing systems, the principles of nanomaterial analysis applied to biomedicine at home and abroad, and the chemical surface modification of various gold nanoparticles.

Application of "smart" multifunctional nanoprobes in tumor diagnosis and treatment

Cancer is one of the major diseases that pose a threat to human health and life, especially because it is difficult to diagnose and cure, and recurs easily. In recent years, the development of nanotechnology has provided researchers with new tools for cancer treatment. In particular, nanoprobes that facilitate integrated diagnosis and treatment, high-resolution imaging, and accurate tumor targeting provide new avenues for the early detection and treatment of cancer. This review focuses on the preparations and applications of two kinds of "smart" multifunctional nanoprobes: "Off-On" nanoprobes and "Charge-Reversal" nanoprobes. This review also briefly discusses their mechanisms of action, as they could provide new ideas for the further development of this field.

Heterometallic nanomaterials: Activity modulation, sensing, imaging and therapy

Heterometallic nanomaterials (HMNMs) display superior physicochemical properties and stability to monometallic counterparts, accompanied by wider applications in the fields of catalysis, sensing, imaging, and therapy due to synergistic effects between multi-metals in HMNMs. So far, most reviews have mainly concentrated on introduction of their preparation approaches, morphology control and applications in catalysis, assay of heavy metal ions, and antimicrobial activity. Therefore, it is very important to summarize the latest investigations of activity modulation of HMNMs and their recent applications in sensing, imaging and therapy. Taking the above into consideration, we briefly underline appealing chemical/physical properties of HMNMs chiefly tailored through the sizes, shapes, compositions, structures and surface modification. Then, we particularly emphasize their widespread applications in sensing of targets (e.g. metal ions, small molecules, proteins, nucleic acids, and cancer cells), imaging (frequently involving photoluminescence, fluorescence, Raman, electrochemiluminescence, magnetic resonance, X-ray computed tomography, photoacoustic imaging, etc.), and therapy (e.g. radiotherapy, chemotherapy, photothermal therapy, photodynamic therapy, and chemodynamic therapy). Finally, we present an outlook on their forthcoming directions. This timely review would be of great significance for attracting researchers from different disciplines in developing novel HMNMs.

Heterometallic nanomaterials display wide applications in the fields of catalysis, sensing, imaging and therapy due to synergistic effects between the multi-metals.

Ultrasmall PEI-Decorated Bi2Se3 Nanodots as a Multifunctional Theranostic Nanoplatform for in vivo CT Imaging-Guided Cancer Photothermal Therapy

Bi-based nanomaterials, such as Bi2Se3, play an important part in biomedicine, such as photothermal therapy (PTT) and computed tomography (CT) imaging. Polyethylenimine (PEI)-modified ultrasmall Bi2Se3 nanodots were prepared using an ultrafast synthetic method at room temperature (25°C). Bi2Se3 nanodots exhibited superior CT imaging performance, and could be used as effective photothermal reagents owing to their broad absorption in the ultraviolet-visible-near infrared region. Under irradiation at 808 nm, PEI-Bi2Se3 nanodots exhibited excellent photothermal-conversion efficiency of up to 41.3%. Good biocompatibility and significant tumor-ablation capabilities were demonstrated in vitro and in vivo. These results revealed that PEI-Bi2Se3 nanodots are safe and a good nanotheranostic platform for CT imaging-guided PTT of cancer.

Recent progress in sensing application of metal nanoarchitecture-enhanced fluorescence

Fluorescence analytical methods, as real time and in situ analytical approaches to target analytes, can offer advantages of high sensitivity/selectivity, great versatility, non-invasive measurement and easy transmission over long distances. However, the conventional fluorescence assay still suffers from low specificity, insufficient sensitivity, poor reliability and false-positive responses. By exploiting various metal nanoarchitectures to manipulate fluorescence, both increased fluorescence quantum yield and improved photostability can be realized. This metal nanoarchitecture-enhanced fluorescence (MEF) phenomenon has been extensively studied and used in various sensors over the past years, which greatly improved their sensing performance. Thus in this review, we primarily give a general overview of MEF based sensors from mechanisms to state-of-the-art applications in environmental assays, biological/medical analysis and diagnosis areas. Finally, their pros and cons as well as further development directions are also discussed.

Inorganic-inorganic nanohybrids for drug delivery, imaging and photo-therapy: recent developments and future scope

Advanced nanotechnology has been emerging rapidly in terms of novel hybrid nanomaterials that have found various applications in day-to-day life for the betterment of the public. Specifically, gold, iron, silica, hydroxy apatite, and layered double hydroxide based nanohybrids have shown tremendous progress in biomedical applications, including bio-imaging, therapeutic delivery and photothermal/dynamic therapy. Moreover, recent progress in up-conversion nanohybrid materials is also notable because they have excellent NIR imaging capability along with therapeutic benefits which would be useful for treating deep-rooted tumor tissues. Our present review highlights recent developments in inorganic-inorganic nanohybrids, and their applications in bio-imaging, drug delivery, and photo-therapy. In addition, their future scope is also discussed in detail.

ICG-loaded gold nano-bipyramids with NIR activatable dual PTT-PDT therapeutic potential in melanoma cells

A great amount of effort is directed towards the progress of cancer treatment approaches aspiring to develop non-invasive, targeted and highly efficient therapies. In this context, Photothermal (PTT) and Photodynamic (PDT) Therapies were proven as promising. This work aims to integrate the therapeutic activities of two near-infrared (NIR) photoactive biomaterials - gold nano-bipyramids (AuBPs) and Indocyanine Green (ICG) - into one single targeted hybrid nanosystem able to operate as dual PTT-PDT agent with higher efficiency compared with each one alone. Firstly, different aspect ratio' AuBPs were systematically investigated in water solution for their intrinsic ability to efficiently generate toxic reactive oxygen species, namely oxygen singlet (¹O₂), under NIR laser irradiation, as this effect is less investigated in literature. Interestingly, the photodynamic activity of AuBPs measured by monitoring the photooxidation of 9,10-Anthracenediyl-bis(methylene)dimalonic acid (ABDA) - a well-known ¹O₂ sensor, is important, counting for 30 % decrease in ABDA optical absorbance for the most active AuBPs, well-correlating with the previously determined photothermal conversion efficiency. Furthermore, ICG was successfully grafted onto the Poly-lactic acid (PLA) coating of plasmonic nanoparticles and, consequently, the as-designed fully integrated hybrid nanosystem shows improved PTT-PDT performance in solution. Specifically, by triggering simultaneous PTT-PDT activities, the ¹O₂ amount is doubled, while the heating monitoring shows higher and faster increase in temperature compared to AuBPs alone. Finally, the efficiency of the combined PTT-PDT therapeutic activity was validated in vitro against B16-F10 cell line by covalent conjugation of the nanosystem with Folic Acid, which ensures the cellular recognition by overexpression of folate receptor.