Investigation of Sub-100 nm Gold Nanoparticles for Laser-Induced Thermotherapy of Cancer

Biomimetic retractable DNA nanocarrier with sensitive responsivity for efficient drug delivery and enhanced photothermal therapy

BACKGROUND

The coalition of DNA nanotechnology with diversiform inorganic nanoparticles offers powerful tools for the design and construction of stimuli-responsive drug delivery systems with spatiotemporal controllability, but it remains challenging to achieve high-density oligonucleotides modification close to inorganic nanocores for their sensitive responsivity to optical or thermal signals.

RESULTS

Inspired by Actinia with retractable tentacles, here we design an artificial nano-Actinia consisted of collapsible DNA architectures attached on gold nanoparticle (AuNP) for efficient drug delivery and enhanced photothermal therapy. The collapsible spheroidal architectures are formed by the hybridization of long DNA strand produced in situ through rolling circle amplification with bundling DNA strands, and contain numerous double-helical segments for the intercalative binding of quercetin as the anti-cancer drug. Under 800-nm light irradiation, the photothermal conversion of AuNPs induces intensive localized heating, which unwinds the double helixes and leads to the disassembly of DNA nanospheres on the surface of AuNPs. The consequently released quercetin can inhibit the expression of heat shock protein 27 and decrease the thermal resistance of tumor cells, thus enhancing photothermal therapy efficacy.

CONCLUSIONS

By combining the deformable DNA nanostructures with gold nanocores, this Actinia-mimetic nanocarrier presents a promising tool for the development of DNA-AuNPs complex and opens a new horizon for the stimuli-responsive drug delivery.

Nanoarchitectured Graphene Organic Framework for Drug Delivery and Chemo-photothermal Synergistic Therapy

The combination of phototherapy and chemotherapy has received extensive attention in the field of cancer therapy. Hence, graphene organic framework (GOF) with a large d-spacing was prepared by solvothermal method, and a novel nanocomposite based on bovine serum albumin (BSA) and the anticancer drug doxorubicin (DOX) was developed, which effectively achieved a photothermal-chemotherapy synergistic treatment. When the feeding ratio was 1:1.6, the DOX loading capacity was 18.51%, and the GOF-BSA/DOX nanocomposite possessed unobvious pH response characteristic, as well as the cumulative release of DOX reached 54.17% at 42°C in the acidic environment (pH = 5.0). The nanocarriers also showed excellent photothermal property and photothermal stability in vitro. In addition, under 808 nm near-infrared laser (NIR) irradiation, the GOF-BSA/DOX nanocomposites generated a large amount of heat, which significantly enhanced the synergistic antitumor effect of in vitro photothermal-chemotherapy. Furthermore, the GOF-BSA/DOX nanocomposites exhibited significantly increased cytotoxicity in the NIR compared with chemotherapy or photothermal therapy alone, suggesting that the combination of chemotherapy and photothermal therapy has excellent antitumor capacity. Therefore, porous GOF nanocarriers may have great potential in combined anti-tumour therapy.

Nanoparticle-assisted, image-guided laser interstitial thermal therapy for cancer treatment

Laser interstitial thermal therapy (LITT) guided by magnetic resonance imaging (MRI) is a new treatment option for patients with brain and non-central nervous system (non-CNS) tumors. MRI guidance allows for precise placement of optical fiber in the tumor, while MR thermometry provides real-time monitoring and assessment of thermal doses during the procedure. Despite promising clinical results, LITT complications relating to brain tumor procedures, such as hemorrhage, edema, seizures, and thermal injury to nearby healthy tissues, remain a significant concern. To address these complications, nanoparticles offer unique prospects for precise interstitial hyperthermia applications that increase heat transport within the tumor while reducing thermal impacts on neighboring healthy tissues. Furthermore, nanoparticles permit the co-delivery of therapeutic compounds that not only synergize with LITT, but can also improve overall effectiveness and safety. In addition, efficient heat-generating nanoparticles with unique optical properties can enhance LITT treatments through improved real-time imaging and thermal sensing. This review will focus on (1) types of inorganic and organic nanoparticles for LITT; (2) in vitro, in silico, and ex vivo studies that investigate nanoparticles' effect on light-tissue interactions; and (3) the role of nanoparticle formulations in advancing clinically relevant image-guided technologies for LITT. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

The Nanosystems Involved in Treating Lung Cancer

Even though there are various types of cancer, this pathology as a whole is considered the principal cause of death worldwide. Lung cancer is known as a heterogeneous condition, and it is apparent that genome modification presents a significant role in the occurrence of this disorder. There are conventional procedures that can be utilized against diverse cancer types, such as chemotherapy or radiotherapy, but they are hampered by the numerous side effects. Owing to the many adverse events observed in these therapies, it is imperative to continuously develop new and improved strategies for managing individuals with cancer. Nanomedicine plays an important role in establishing new methods for detecting chromosomal rearrangements and mutations for targeted chemotherapeutics or the local delivery of drugs via different types of nano-particle carriers to the lungs or other organs or areas of interest. Because of the complex signaling pathways involved in developing different types of cancer, the need to discover new methods for prevention and detection is crucial in producing gene delivery materials that exhibit the desired roles. Scientists have confirmed that nanotechnology-based procedures are more effective than conventional chemotherapy or radiotherapy, with minor side effects. Several nanoparticles, nanomaterials, and nanosystems have been studied, including liposomes, dendrimers, polymers, micelles, inorganic nanoparticles, such as gold nanoparticles or carbon nanotubes, and even siRNA delivery systems. The cytotoxicity of such nanosystems is a debatable concern, and nanotechnology-based delivery systems must be improved to increase the bioavailability, biocompatibility, and safety profiles, since these nanosystems boast a remarkable potential in many biomedical applications, including anti-tumor activity or gene therapy. In this review, the nanosystems involved in treating lung cancer and its associated challenges are discussed.

Polythiolactone-Decorated Silica Particles: A Versatile Approach for Surface Functionalization, Catalysis and Encapsulation

The surface chemistry of colloidal silica has tremendous effects on its properties and applications. Commonly the design of silica particles is based on their de novo synthesis followed by surface functionalization leading to tailormade properties for a specific purpose. Here, the design of robust "precursor" polymer-decorated silica nano- and microparticles is demonstrated, which allows for easy post-modification by polymer embedded thiolactone chemistry. To obtain this organic-inorganic hybrid material, silica particles (SiO2 P) were functionalized via surface-initiated atom transfer radical polymerization (SI-ATRP) with poly(2-hydroxyethyl acrylate) (PHEA)-poly(thiolactone acrylamide (PThlAm) co-polymer brushes. Exploiting the versatility of thiolactone post-modification, a system was developed that could be used in three exemplary applications: 1) the straightforward molecular post-functionalization to tune the surface polarity, and therefore the dispersibility in various solvents; 2) the immobilization of metal nanoparticles into the polymer brushes via the in situ formation of free thiols that preserved catalytic activity in a model reaction; 3) the formation of redox-responsive, permeable polymer capsules by crosslinking the thiolactone moieties with cystamine dihydrochloride (CDH) followed by dissolution of the silica core.

Rational Design of Albumin Theranostic Conjugates for Gold Nanoparticles Anticancer Drugs: Where the Seed Meets the Soil?

Multifunctional gold nanoparticles (AuNPs) may serve as a scaffold to integrate diagnostic and therapeutic functions into one theranostic system, thereby simultaneously facilitating diagnosis and therapy and monitoring therapeutic responses. Herein, albumin-AuNP theranostic agents have been obtained by conjugation of an anticancer nucleotide trifluorothymidine (TFT) or a boron-neutron capture therapy drug undecahydro-closo-dodecaborate (B₁₂H₁₂) to bimodal human serum albumin (HSA) followed by reacting of the albumin conjugates with AuNPs. In vitro studies have revealed a stronger cytotoxicity by the AuNPs decorated with the TFT-tagged bimodal HSA than by the boronated albumin conjugates. Despite long circulation time, lack of the significant accumulation in the tumor was observed for the AuNP theranostic conjugates. Our unique labelling strategy allows for monitoring of spatial distribution of the AuNPs theranostic in vivo in real time with high sensitivity, thus reducing the number of animals required for testing and optimizing new nanosystems as chemotherapeutic agents and boron-neutron capture therapy drug candidates.

Gold Nanoparticles for Vectorization of Nucleic Acids for Cancer Therapeutics

Cancer remains a complex medical challenge and one of the leading causes of death worldwide. Nanomedicines have been proposed as innovative platforms to tackle these complex diseases, where the combination of several treatment strategies might enhance therapy success. Among these nanomedicines, nanoparticle mediated delivery of nucleic acids has been put forward as key instrument to modulate gene expression, be it targeted gene silencing, interference RNA mechanisms and/or gene edition. These novel delivery systems have strongly relied on nanoparticles and, in particular, gold nanoparticles (AuNPs) have paved the way for efficient delivery systems due to the possibility to fine-tune their size, shape and surface properties, coupled to the ease of functionalization with different biomolecules. Herein, we shall address the different molecular tools for modulation of expression of oncogenes and tumor suppressor genes and discuss the state-of-the-art of AuNP functionalization for nucleic acid delivery both in vitro and in vivo models. Furthermore, we shall highlight the clinical applications of these spherical AuNP based conjugates for gene delivery, current challenges, and future perspectives in nanomedicine.

Laser enhancement of cancer cell destruction by photothermal therapy conjugated glutathione (GSH)-coated small-sized gold nanoparticles

The current study presents the employment of glutathione (GSH)-modified small-sized gold nanoparticles (AuNPs) ~ 3 nm in photothermal therapy (PTT), to evaluate the targeting and the toxic effect of cancer rather than normal cells. GSH is pH-sensitive surfaces that exhibit a fast response to the variation in pH conditions between normal (~ 7.4) and cancer cells (6-6.5). Results showed a considerable toxic impact via GSH-AuNP accumulation in cancer cells by both green and NIR laser irradiation. A proportional relation of cellular death to AuNP concentration, exposure time, and light-to-heat conversion efficiency has been demonstrated. The small-sized GSH-AuNPs represent promising agents for developing the safety issues of photothermal cancer treatment by the selective targeting of cancer rather than normal cells, reducing the NP toxicity by their size overlapping with the renal clearance barrier of kidney filtration (~ 5.5 nm), and promoting the photothermal performance in the NIR region, in which light penetration into deep cancer regions is more interested.

NIR triggered glycosylated gold nanoshell as a photothermal agent on melanoma cancer cells

Nowadays, gold nanoshells are used in targeted nano photothermal cancer therapy. This study surveyed the application of gold nanoshell (GNs) to thermal ablative therapy for melanoma cancer cells and it takes advantage of the near infrared absorption of gold nanoshells. The synthesis and characterization of glycosylated gold nanoshells (GGNs) were done. The cytotoxicity and photothermal effects of GNs on melanoma cells were evaluated using MTT assay and flow cytometry. The characterization data showed that GGNs are spherical, with a hydrodynamic size of 46.7 nm. Results suggest that the cellular uptake of GGNs was about 78%. Viability assays showed no significant toxicity at low concentrations of GNs. The higher heating rate and toxicity of cancer cells were obtained for the cells exposed to 808 nm NIR laser after incubation with GGNs rather than the GNs. The viability of these cells has dramatically decreased by 29%. Furthermore, 61% more cell lethality was achieved for A375 cells using combined photothermal therapy and treatment with GGNs in comparison to NIR radiation alone. In conclusion, our findings suggest that the synthesized gold/silica core-shell nanoparticles conjugated with glucosamine have high potentials to be considered as an efficient metal-nanoshell in the process of targeted cancer photothermal therapy.

Engineered Gold-Based Nanomaterials: Morphologies and Functionalities in Biomedical Applications. A Mini Review

In the last decade, several engineered gold-based nanomaterials, such as spheres, rods, stars, cubes, hollow particles, and nanocapsules have been widely explored in biomedical fields, in particular in therapy and diagnostics. As well as different shapes and dimensions, these materials may, on their surfaces, have specific functionalizations to improve their capability as sensors or in drug loading and controlled release, and/or particular cell receptors ligands, in order to get a definite targeting. In this review, the up-to-date progress will be illustrated regarding morphologies, sizes and functionalizations, mostly used to obtain an improved performance of nanomaterials in biomedicine. Many suggestions are presented to organize and compare the numerous and heterogeneous experimental data, such as the most important chemical-physical parameters, which guide and control the interaction between the gold surface and biological environment. The purpose of all this is to offer the readers an overview of the most noteworthy progress and challenges in this research field.

Thermodynamics of adsorption of lysozyme on gold nanoparticles from second harmonic light scattering

Gold nanoparticle (GNP) interaction with hen egg white lysozyme (Lyz) has been investigated by many groups in order to understand protein mediated aggregation of GNPs and the underlying mechanism of aggregation. In this article, we have studied the interaction of citrate-capped GNPs of 16, 28, 41, and 69 nm sizes with Lyz by the non-destructive label-free second harmonic light scattering (SHLS) technique at physiological pH in phosphate buffer. The surface sensitivity of the nonlinear optical SHLS technique is very high and we have looked at the GNP-Lyz interaction at nanomolar concentrations. We have followed the increase in the SHLS intensity of GNPs as a function of the added concentration of Lyz in small aliquots. The SH intensity profile exhibits saturation behaviour and was fitted with a modified Langmuir adsorption model which yielded the binding constant (Kb), the binding stoichiometry (nsat) at saturation and the free energy change (ΔG) in the adsorption process. The free energy change was further decomposed into changes in the enthalpy (ΔH) and entropy (ΔS) of adsorption by carrying out temperature dependent SHLS measurements in a specially designed cell. The thermodynamic quantities extracted from the measurements show that the binding is exothermic (ΔH < 0) as well as spontaneous (ΔS > 0). We find that the first step in the adsorption of Lyz on the GNP surface is nanoparticle protein corona (NP-PC) formation driven predominantly by electrostatic attraction. In the second step of adsorption, the adsorbed lysozymes on the surface form a bridge between two or more GNPs leading to the latter's aggregation, which is the main reason for the enhancement of the SH scattering signal. Although the interaction between the GNPs and Lyz is driven by strong electrostatic attraction, the thermodynamic quantities reported here indicate that the protein is physisorbed on the nanoparticle surface. We have also demonstrated that SHLS provides a new tool for full thermodynamic characterization of protein adsorption on metal nanoparticles at ultralow concentrations.

Glowing gold nanoparticle coating: restoring the lost property from bulk gold

The unique electronic, optical, and catalytic properties of AuNPs caused by localized surface plasmon resonance (LSPR) have attracted many scientists, but the LSPR diminishes the captivating luster of bulk gold. An exciting challenge is the fabrication of golden-colored AuNPs, but a decisive factor for controlling the absorption/reflection of AuNPs remains elusive. We now propose a simple and versatile method for the fabrication of glowing AuNPs to restore the "lost golden color" of AuNPs in combination with the deposition of AuNPs on a cellulose filter or a PET/cotton fabric by the successive ionic layer adsorption and reaction (SILAR) method and simple pencil drawing. The obtained materials exhibited the glowing golden-color on the pencil-drawn surface and common red and blue colors on the other parts. Surprisingly, the golden-colored AuNPs still maintain a catalytic activity different from that of bulk gold and could be used as a catalyst for the reduction of p-nitrophenol, pendimethalin or 2,4-dinitrophenol in the presence of NaBH₄. We believe that the re-endowment of such a property characteristic of bulk gold into gold nanomaterials would lead to further advancement in the arts and culture as well as electronics, optics, and catalysis.

Radiolabeled Molecular Imaging Probes for the In Vivo Evaluation of Cellulose Nanocrystals for Biomedical Applications

Cellulose nanocrystals (CNCs) have remarkable potential to improve the delivery of diagnostic and therapeutic agents to tumors; however, the in vivo studies on CNC biodistribution are still limited. We developed CNC-based imaging probes for the in vitro and in vivo evaluation using two labeling strategies: site-specific hydrazone linkage to the terminal aldehyde of the CNC and nonsite-specific activation using 1,1'-carbonyldiimidazole (CDI). The in vivo behavior of unmodified CNC, DOTA-CNC (ald.), and DOTA-CNC (OH) was investigated in healthy and 4T1 breast cancer mouse models. They displayed good biocompatibility in cell models. Moreover, the biodistribution profile and SPECT/CT imaging confirmed that the accumulation of ¹¹¹In-labeled DOTA-CNC (ald.) and ¹¹¹In-DOTA-CNC (OH) was primarily in hepatic, splenic, and pulmonary ducts in accordance with the clearance of nontargeted nanoparticles. The developed CNC imaging probes can be used to obtain information with noninvasive imaging on the behavior in vivo to guide structural optimization for targeted delivery.

Magnetic field-inducible drug-eluting nanoparticles for image-guided thermo-chemotherapy

Multifunctional nanoparticles integrating cancer cell imaging and treatment modalities into a single platform are recognized as a promising approach; however, their development currently remains a challenge. In this study, we synthesized magnetic field-inducible drug-eluting nanoparticles (MIDENs) by embedding superparamagnetic iron oxide nanoparticles (Fe₃O₄; SPIONs) and cancer therapeutic drugs (doxorubicin; DOX) in a temperature-responsive poly (lactic-co-glycolic acid) (PLGA) nanomatrix. Application of an external alternating magnetic field (AMF) generated heat above 42 °C and subsequent transition of the PLGA polymer matrix (T_g = 42-45 °C) from the glassy to the rubbery state, facilitating the controlled release of the loaded DOX, ultimately allowing for simultaneous hyperthermia and local heat-triggered chemotherapy for efficient dual cancer treatment. The average size of the synthesized MIDENs was 172.1 ± 3.20 nm in diameter. In vitro studies showed that the MIDENs were cytocompatible and especially effective in destroying CT26 colon cancer cells with AMF application. In vivo studies revealed that the MIDENs enabled enhanced T₂ contrast magnetic resonance imaging and a significant suppression of malignant tumor growth under an AMF. Our multifunctional MIDENs, composed of biocompatible substances and therapeutic/imaging modalities, will be greatly beneficial for cancer image-guided thermo-chemotherapy applications.

Important parameters for optimized metal nanoparticles-aided electromagnetic field (EMF) effect on cancer

Background

A number of experimental research findings for the metal nanoparticles (NPs)-mediated EMF photothermal therapy of cancer cells show an intriguing trend of the NPs’ size-dependent efficacy. This is a phenomenon we find to trend with the light absorption bandwidth behavior (full width at half maximum) of the NPs and the accompanying electric field enhancement. We find that the nanoparticle sizes that have been reported to produce the optimized effect on cancer cells are of minimum absorption bandwidth and optimized electric field magnitude. While the death of cancer cells under the NPs-aided EMF effect has in the past attracted varied interpretations, either as a thermal or non-thermal effect, photothermal effect has gained a wide acceptance due to the exhibited hyperthermia. However, the exhibited trend of the NPs’ size-dependent efficacy is beginning to feature as a possible manifestation of other overlooked underlying or synergistic phenomenal conditions.

Method

We present a theoretical model and analysis which reveal that the contribution and efficacy of the metal NPs in the destruction of cancer depend partly but significantly on the accompanying electric field intensity enhancement factor and partly on their absorption cross-section.

Results

This paper finds that, other than the expected hyperthermia, the metal NPs’ sizes for the optimized therapy on cancer cells seem to fulfill other synergistic conditions which need to come to the fore. We find interplay between electric field and thermal effects as independent energy channels where balancing may be important for the optimized EMF effect, in the ratio of about 5:1. The required balancing depends on the absorption bandwidth and absorption cross-section of the NPs, the frequency of EMF used and the relative permittivity of the cancer cells. The NPs’ size-dependent efficacy decreases away from the NPs’ size of minimum absorption bandwidth, which is around 20 nm for Au NPs or other shapes of equivalent surface area–volume ratio. While the absorption wavelength peak for metal NPs would change with the change of shape, the responsible condition(s) for optimizing the efficacy remains relatively invariable.

Conclusion

From the modeling and the analysis of the NPs’ size for optimizing the EMF therapy on cancer cells, the ratio of electric field enhancement by metal NPs to the associated thermal effect is a very important factor for efficacy.

In-vitro Study of Photothermal Anticancer Activity of Carboxylated Multiwalled Carbon Nanotubes

BACKGROUND AND OBJECTIVE

Multi-walled Carbon Nano Tubes (MWCNTs) as an important element of nanosciences have a remarkable absorption in the region of NIR window (650-900 nm) which can overcome the limitations of deep treatment in photothermal therapy. To disperse MWCNTs in water, it is proposed to attach carboxylated functional group (-COOH) to MWCNTs in order to increase dispersivity in water.

MATERIALS AND METHODS

A stable suspension of MWCNTs-COOH with different concentrations (from 2.5 to 500 μg/ml) was prepared. Then, they were compared for their ability to increase temperature in the presence of 810 nm laser irradiation and through a wide range of radiation time (from 20 to 600 s) and three laser powers (1.5, 2 and 2.5 w). The temperature rise was recorded real time every 20 seconds by a precise thermometer.

RESULTS

Absorption spectrum of MWCNTs-COOH suspension was remarkably higher than water in a wavelength range of 200 to 1100 nm. For example, using the concentrations of 2.5 and 80 μg/ml of MWCNTs-COOH suspension caused a temperature elevation 2.35 and 9.23 times compared to water, respectively, upon 10 min laser irradiation and 2.5 w. Moreover, this predominance can be observed for 1.5 and 2 w radiation powers, too. Our findings show that the maximum of temperature increase was obtained at 80 μg/ml concentration of MWCNT-COOH suspension for three powers and through all periods of exposure time. Our results show that the minimum required parameters for a 5°C temperature increase (a 5°C temperature increase causes cell death) were achieved through 2.5 w, 28 μg/ml concentration and 20 second irradiation time in which both concentration and radiation times were relatively low.

CONCLUSION

Our results showed that MWCNTs-COOH can be considered as a potent photothermal agent in targeted therapies. New strategies must be developed to minimize the concentration, irradiation time and radiation power used in experiments.

Engineered gold nanoparticles for photothermal cancer therapy and bacteria killing

Gold nanoparticle mediated photothermal therapy in future medicine.

Stability and binding interaction of bilirubin on a gold nano-surface: steady state fluorescence and FT-IR investigation

A gold nanoparticle exhibits strong absorption and emission due to its unique physical geometry and surface plasmon resonance phenomena. A further modification with organic molecules makes it more appropriate for biological applications. The current manuscript illustrated the optical behavior and stability of bilirubin (BR) coated gold (AuBR) nanoparticles, using BR itself as a reducing agent. In addition, FT-IR and steady state fluorescence measurements were performed to illustrate the binding interaction of BR with the Au(III) ion and the nanoparticles. BR showed a strong affinity towards Au(III) and the measured binding constant was ∼4.3 × 10(5) M(-1). It caused reduction of the Au(III) ion and rendered the formation of cubic face centered AuBR nanoparticles, which were ∼20 nm in diameter. The particles were stabilized as BR was bound to the gold nanoparticle surface, which was confirmed by FT-IR measurement. An intense carboxyl C=O stretching vibration at 1695 cm(-1) was observed for the BR powder but was absent for the AuBR nanoparticles. However, two weak bands at ∼1563 and 1391 cm(-1), presumably due to the asymmetric and symmetric stretching vibrations of the carboxylate form (COO(-)), were found for the AuBR nanoparticles. A stretching vibration of lactam C[double bond, length as m-dash]O appeared at 1645 cm(-1) for BR and the band was shifted to 1647 cm(-1) for the AuBR nanoparticles. The stretching modes of pyrrole N-H and lactam N-H were detected at 3406 cm(-1) and 3267 cm(-1), respectively, for BR. However, the pyrrole N-H band shifted to 3446 cm(-1) and became broader for the AuBR nanoparticles. The observed blue shift in the lactam C[double bond, length as m-dash]O and N-H vibrations of the AuBR nanoparticles indicated a weakening/absence of internal hydrogen bonds between the carboxyl groups and the four N-H bonds in the BR moiety. The binding of BR to the surface provides great stability to the nanoparticles, which remained monodispersed in the large pH range (pH 4 to 12) for more than a month. However, under acidic pH conditions the particles associated to form bigger particles and the plasmon resonance band shifted as they grew; the plasmon resonance band shifted from 525 nm (at pH 7.0) to 555 nm (at pH 3.0). The particles also remained stable in the presence of a higher concentration of salt (KCl and NaCl) in the dispersing media.

Interaction of gold nanoparticles with proteins and cells

Gold nanoparticles (Au NPs) possess many advantages such as facile synthesis, controllable size and shape, good biocompatibility, and unique optical properties. Au NPs have been widely used in biomedical fields, such as hyperthermia, biocatalysis, imaging, and drug delivery. The broad application range may result in hazards to the environment and human health. Therefore, it is important to predict safety and evaluate therapeutic efficiency of Au NPs. It is necessary to establish proper approaches for the study of toxicity and biomedical effects. In this review, we first focus on the recent progress in biological effects of Au NPs at the molecular and cellular levels, and then introduce key techniques to study the interaction between Au NPs and proteins. Knowledge of the biomedical effects of Au NPs is significant for the rational design of functional nanomaterials and will help predict their safety and potential applications.

Off to the organelles - killing cancer cells with targeted gold nanoparticles

Gold nanoparticles (AuNPs) are excellent tools for cancer cell imaging and basic research. However, they have yet to reach their full potential in the clinic. At present, we are only beginning to understand the molecular mechanisms that underlie the biological effects of AuNPs, including the structural and functional changes of cancer cells. This knowledge is critical for two aspects of nanomedicine. First, it will define the AuNP-induced events at the subcellular and molecular level, thereby possibly identifying new targets for cancer treatment. Second, it could provide new strategies to improve AuNP-dependent cancer diagnosis and treatment.

Our review summarizes the impact of AuNPs on selected subcellular organelles that are relevant to cancer therapy. We focus on the nucleus, its subcompartments, and mitochondria, because they are intimately linked to cancer cell survival, growth, proliferation and death. While non-targeted AuNPs can damage tumor cells, concentrating AuNPs in particular subcellular locations will likely improve tumor cell killing. Thus, it will increase cancer cell damage by photothermal ablation, mechanical injury or localized drug delivery. This concept is promising, but AuNPs have to overcome multiple hurdles to perform these tasks. AuNP size, morphology and surface modification are critical parameters for their delivery to organelles. Recent strategies explored all of these variables, and surface functionalization has become crucial to concentrate AuNPs in subcellular compartments.

Here, we highlight the use of AuNPs to damage cancer cells and their organelles. We discuss current limitations of AuNP-based cancer research and conclude with future directions for AuNP-dependent cancer treatment.

Au-nanomaterials as a superior choice for near-infrared photothermal therapy

Photothermal therapy (PPT) is a platform to fight cancer by using multiplexed interactive plasmonic nanomaterials as probes in combination with the excellent therapeutic performance of near-infrared (NIR) light. With recent rapid developments in optics and nanotechnology, plasmonic materials have potential in cancer diagnosis and treatment, but there are some concerns regarding their clinical use. The primary concerns include the design of plasmonic nanomaterials which are taken up by the tissues, perform their function and then clear out from the body. Gold nanoparticles (Au NPs) can be developed in different morphologies and functionalized to assist the photothermal therapy in a way that they have clinical value. This review outlines the diverse Au morphologies, their distinctive characteristics, concerns and limitations to provide an idea of the requirements in the field of NIR-based therapeutics.