Gold nanoparticles induce nuclear damage in breast cancer cells, which is further amplified by hyperthermia

The nucleolus: Coordinating stress response and genomic stability

The perception that the nucleoli are merely the organelles where ribosome biogenesis occurs is challenged. Only around 30 % of nucleolar proteins are solely involved in producing ribosomes. Instead, the nucleolus plays a critical role in controlling protein trafficking during stress and, according to its dynamic nature, undergoes continuous protein exchange with nucleoplasm under various cellular stressors. Hence, the concept of nucleolar stress has evolved as cellular insults that disrupt the structure and function of the nucleolus. Considering the emerging role of this organelle in DNA repair and the fact that rDNAs are the most fragile genomic loci, therapies targeting the nucleoli are increasingly being developed. Besides, drugs that target ribosome synthesis and induce nucleolar stress can be used in cancer therapy. In contrast, agents that regulate nucleolar activity may be a potential treatment for neurodegeneration caused by abnormal protein accumulation in the nucleolus. Here, I explore the roles of nucleoli beyond their ribosomal functions, highlighting the factors triggering nucleolar stress and their impact on genomic stability.

Strategies for the Nuclear Delivery of Metal Complexes to Cancer Cells

The nucleus is an essential organelle for the function of cells. It holds most of the genetic material and plays a crucial role in the regulation of cell growth and proliferation. Since many antitumoral therapies target nucleic acids to induce cell death, tumor-specific nuclear drug delivery could potentiate therapeutic effects and prevent potential off-target side effects on healthy tissue. Due to their great structural variety, good biocompatibility, and unique physico-chemical properties, organometallic complexes and other metal-based compounds have sparked great interest as promising anticancer agents. In this review, strategies for specific nuclear delivery of metal complexes are summarized and discussed to highlight crucial parameters to consider for the design of new metal complexes as anticancer drug candidates. Moreover, the existing opportunities and challenges of tumor-specific, nucleus-targeting metal complexes are emphasized to outline some new perspectives and help in the design of new cancer treatments.

Acute toxicity study of onion peel-derived gold nano-bioconjugate

The acute anti-inflammatory activity of onion peel-derived gold nano-bioconjugate was already established earlier. The current study was aimed to investigate the acute oral toxicity of onion peel-derived gold nano-bioconjugate (GNBC) for safe therapeutic utilization in vivo. The acute toxicity study was carried out in female mice for 15 days and showed no mortality and any abnormal complications. The lethal dose (LD50) was evaluated and found to be higher than 2000 mg/kg. After 15 days, animals were euthanized and hematological, and biochemical analyses were performed. In all hematological and biochemical assays, treated animals did not show significant toxicity when compared to the control group. The body weight, behavior, and histopathological studies showed that GNBC is nontoxic. Thereby, the results suggest that onion peel-derived gold nano-bioconjugate GNBC can be utilized for therapeutic applications in vivo.

Gold nanoparticles-based photothermal therapy for breast cancer

AuNPs-mediated photothermal therapy (PTT) is gaining popularity in both laboratory research and medical applications. It has proven clear advantages in breast cancer therapy over conventional thermal ablation because of its easily-tuned features of irradiation light with inside hyperthermia ability. Notwithstanding this significant progress, the therapeutic potential of AuNPs-mediated PTT in cancer treatments is still impeded by several challenges, including inherent non-specificity, low photothermal conversion effectiveness, and the limitation of excitation light tissue penetration. Given the rapid progress of AuNPs-mediated PTT, we present a comprehensive overview of significant breakthroughs in the recent advancements of AuNPs for PTT, focusing on breast cancer cells. With the improvement of chemical synthesis technology, AuNPs of various sizes and shapes with desired properties can be synthesized, allowing breast cancer targeting and treatment. In this study, we summarized the different sizes and features of four major types of AuNPs in this review: Au nanospheres, Au nanocages, Au nanoshells, and Au nanorods, and explored their benefits and drawbacks in PTT. We also discussed the diagnostic, bioconjugation, targeting, and cellular uptake of AuNPs, which could improve the performance of AuNP-based PTT. Besides that, potential challenges and future developments of AuNP-mediated PTT for clinical applications are discussed. AuNP-mediated PTT is expected to become a highly promising avenue in cancer treatment in the near future.

Organelle-targeted therapies: a comprehensive review on system design for enabling precision oncology

Cancer is a major threat to human health. Among various treatment methods, precision therapy has received significant attention since the inception, due to its ability to efficiently inhibit tumor growth, while curtailing common shortcomings from conventional cancer treatment, leading towards enhanced survival rates. Particularly, organelle-targeted strategies enable precise accumulation of therapeutic agents in organelles, locally triggering organelle-mediated cell death signals which can greatly reduce the therapeutic threshold dosage and minimize side-effects. In this review, we comprehensively discuss history and recent advances in targeted therapies on organelles, specifically including nucleus, mitochondria, lysosomes and endoplasmic reticulum, while focusing on organelle structures, organelle-mediated cell death signal pathways, and design guidelines of organelle-targeted nanomedicines based on intervention mechanisms. Furthermore, a perspective on future research and clinical opportunities and potential challenges in precision oncology is presented. Through demonstrating recent developments in organelle-targeted therapies, we believe this article can further stimulate broader interests in multidisciplinary research and technology development for enabling advanced organelle-targeted nanomedicines and their corresponding clinic translations.

Effects of temperature on the toxicity of waterborne nanoparticles under global warming: Facts and mechanisms

Global climate change is predicted to increase the average temperature of aquatic environments. Temperature changes modulate the toxicity of emerging chemical contaminants, such as nanoparticles (NPs). However, current hazard assessments of waterborne NPs seldom consider the influence of temperature. In this review, we gathered and analyzed the effects of temperature on the toxicity of waterborne NPs in different organisms. There was a general decrease in bioavailability with increasing temperature in algae and plants due to NPs aggregation, thus, reducing their toxicities. However, the agglomerated large particles caused by the increase in temperature induce a shading effect and inhibit algal photosynthesis. The toxicity of NPs in microorganisms and aquatic animals increases with increasing temperature. This may be due to the significant influence of high temperature on the uptake and excretion of chemicals across membranes, which increase the production of reactive oxygen species and enhance oxidative damage to organisms. High temperature also affect the formation and composition of a protein corona on NPs, altering their toxicity. Our results provide new insights into the toxicity of NPs in the context of global warming, and highlight the deficiencies of current research on NPs.

Novel combination of multi-walled carbon nanotubes and gold nanocomposite for photothermal therapy in human breast cancer model

Despite current medical advancements, the resistance of malignant tumours to conventional medical therapies highlights the need for innovative therapeutic techniques. Numerous studies have focused on the promising application of nanomaterials in recent years. Nanoparticles (NPs) are used to treat cancer. Plasmonic photothermal therapy (PPTT) is a cancer-ablation technique in which photon energy is rapidly converted into heat by some radiative and non-radiative events. Gold NPs (Au-NPs) and carbon nanotubes (CNTs) are plasmonic NPs with excellent thermal conductivity and their near-infrared (NIR) absorbance has several interesting qualities. Additionally, CNTs could penetrate cells. In this study, Au-NPs were used to fabricate multi-walled CNTs (MWCNTs), which could boost its efficacy in cancer treatment in accordance with PPTT. Transmission electron microscopy, field-emission scanning electron microscopy (FESEM), atomic force microscopy and FTIR were used to examine the MWCNTs made from walnut shell. Au-NPs were explored using green chemistry and MWCNT-COOAu, MWCNT-COO and MWCNT-Au were examined by Raman, EDX and FESEM techniques. The effect of MWCNT-COOAu, MWCNT-COO and MWCNT-Au at various concentrations (3.12, 6.25, 12.5 and 25 µg/mL) and irradiation time intervals (30, 60, 90 and 120 sec) by using NIR laser under λ = 1064 nm and P = 3 W on the breast cancer cell line (MCF7) was investigated. The highest temperatures for MWCNT-COO, MWCNT-COOAu and MWCNT-Au were determined to be 44.1 °C, 46 °C and 46.9 °C, respectively, which produced 61.66 %, 72 % and 85.3 % cytotoxicity, respectively, in MCF7 cell line at a concentration of 25 µg/mL and an irradiation period of 120 sec. The treatment of MCF7 cell line by photothermal therapy was found to be in a concentration- and time-dependent manner.

Gold Nanoparticles Contact with Cancer Cell: A Brief Update

The fine-tuning of the physicochemical properties of gold nanoparticles has facilitated the rapid development of multifunctional gold-based nanomaterials with diagnostic, therapeutic, and therapeutic applications. Work on gold nanoparticles is increasingly focusing on their cancer application. This review provides a summary of the main biological effects exerted by gold nanoparticles on cancer cells and highlights some critical factors involved in the interaction process (protein corona, tumor microenvironment, surface functionalization). The review also contains a brief discussion of the application of gold nanoparticles in target discovery.

Phytochemical-conjugated bio-safe gold nanoparticles in breast cancer: a comprehensive update

Breast cancer is the most common malignancy in women and is rated among one of the three common malignancies worldwide in combination with colon and lung cancer. The escalating mortality rate of breast cancer patients has captivated the attention of the present-day researchers to come up with new management options. According to WHO, early detection, timely diagnosis and comprehensive breast cancer management are the three cornerstones for controlling breast cancer incidences per year. Multidisciplinary theragnostic approaches for simultaneous diagnosis and treatment of breast cancer have further enriched the therapeutic arsenal. Imaging and biopsy play a significant role in the diagnosis of breast cancer. The treatment plan mostly initiates with general surgery or radiation therapy followed up with adjuvant and/or neoadjuvant therapy. Conventional chemotherapeutics in breast cancer suffer from toxicity and lack of site specificity. Bio-safe gold nanoparticles hold sufficient promise for bridging this gap. Diverse phytochemicals-based synthesis routes to arrive at nano-dimensional gold with spotlight on reaction mechanisms, reaction variables, specific advantages, toxicity and their influence in breast cancer conditions are the focus of this work. This review marks the first attempt to explore the potential of phytochemical-derived nano-gold in breast cancer treatment.

Recent advances in targeted nanotherapeutic approaches for breast cancer management

Breast cancer is the most commonly occurring tumor disease worldwide. Breast cancer is currently managed by conventional chemotherapy, which is inadequate in curbing this heterogeneous disease and results in off-site toxic effects, suggesting effective treatment approaches with better therapeutic profiles are needed. This review, therefore, focuses on the recent advancements in delivering therapeutics to the target site using passive and/or active targeted nanodrug-delivery systems to ameliorate endolysosomal escape. In addition, recent strategies in targeting breast cancer stem cells are discussed. The role of naturally cell-secreted nanovesicles (exosomes) in the management of triple-negative breast cancer is also discussed.

Recent advances in active targeting of nanomaterials for anticancer drug delivery

One of the challenges in cancer chemotherapy is the low target to non-target ratio of therapeutic agents which incur severe adverse effect on the healthy tissues. In this regard, nanomaterials have tremendous potential for impacting cancer therapy by altering the toxicity profile of the drug. Some of the striking advantages provided by the nanocarriers mediated targeted drug delivery are relatively high build-up of drug concentration at the tumor site, improved drug content in the formulation and enhanced colloidal stability. Further, nanocarriers with tumor-specific moieties can be targeted to the cancer cell through cell surface receptors, tumor antigens and tumor vasculatures with high affinity and accuracy. Moreover, it overcomes the bottleneck of aimless drug biodistribution, undesired toxicity and heavy dosage of administration. This review discusses the recent developments in active targeting of nanomaterials for anticancer drug delivery through cancer cell surface targeting, organelle specific targeting and tumor microenvironment targeting strategies. Special emphasis has been given towards cancer cell surface and organelle specific targeting as delivery of anticancer drugs through these routes have made paradigm change in cancer management. Further, the current challenges and future prospects of nanocarriers mediated active drug targeting are also demonstrated.

Intracellular and extracellular targets as mechanisms of cancer therapy by nanomaterials in relation to their physicochemical properties

Cancer nanomedicine has evolved in recent years and is only expected to increase due to the ease with which nanomaterials (NMs) may be manipulated to the advantage of the cancer patient. The success of nanomedicine is dependent on the cell death mechanism, which in turn is dependent on the organelle initially targeted. The success of cancer nanomedicine is also dependent on other cellular mechanisms such as the induction of autophagy dysfunction, manipulation of the tumor microenvironment (TME) and secretome or induction of host immune responses. Current cancer phototherapies for example, photothermal- or photodynamic therapies as well as radio enhancement also form a major part of cancer nanomedicine. In general, cancer nanomedicine may be grouped into those NMs exhibiting inherent anti-cancer properties that is, self-therapeutic NMs (Group 1), NMs leading to localization of phototherapies or radio-enhancement (Group 2), and NMs as nanocarriers in the absence or presence of external radiation (Group 3). The recent advances of these three groups, together with their advantages and disadvantages as well as their cellular mechanisms and ultimate outcomes are summarized in this review. By exploiting these different intracellular mechanisms involved in initiating cell death pathways, it is possible to synthesize NMs that may have the desirable characteristics to maximize their efficacy in cancer therapy. Therefore, a summary of these important physicochemical characteristics is also presented that need to be considered for optimal cancer cell targeting and initiation of mechanisms that will lead to cancerous cell death. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Tri-modal imaging of gold-dotted magnetic nanoparticles for magnetic resonance imaging, computed tomography and intravascular ultrasound: an in vitro study

Aim: To examine the multimodal contrasting ability of gold-dotted magnetic nanoparticles (Au*MNPs) for magnetic resonance (MR), computed tomography (CT) and intravascular ultrasound (IVUS) imaging. Materials & methods: Au*MNPs were prepared by adapting an impregnation method, without using surface capping reagents and characterized (transmission electron microscopy, x-ray diffraction and Fourier-transform infrared spectroscopy) with their in vitro cytotoxicity assessed, followed by imaging assessments. Results: The contrast-enhancing ability of Au*MNPs was shown to be concentration-dependent across MR, CT and IVUS imaging. The Au content of the Au*MNP led to evident increases of the IVUS signal. Conclusion: We demonstrated that Au*MNPs showed concentration-dependent contrast-enhancing ability in MRI and CT imaging, and for the first-time in IVUS imaging due to the Au content. These Au*MNPs are promising toward solidifying tri-modal imaging-based theragnostics.

Simultaneous label-free live imaging of cell nucleus and luminescent nanodiamonds

In recent years, fluorescent nanodiamond (fND) particles containing nitrogen-vacancy (NV) centers gained recognition as an attractive probe for nanoscale cellular imaging and quantum sensing. For these applications, precise localization of fNDs inside of a living cell is essential. Here we propose such a method by simultaneous detection of the signal from the NV centers and the spectroscopic Raman signal from the cells to visualize the nucleus of living cells. However, we show that the commonly used Raman cell signal from the fingerprint region is not suitable for organelle imaging in this case. Therefore, we develop a method for nucleus visualization exploiting the region-specific shape of C-H stretching mode and further use k-means cluster analysis to chemically distinguish the vicinity of fNDs. Our technique enables, within a single scan, to detect fNDs, distinguish by chemical localization whether they have been internalized into cell and simultaneously visualize cell nucleus without any labeling or cell-fixation. We show for the first time spectral colocalization of unmodified high-pressure high-temperature fND probes with the cell nucleus. Our methodology can be, in principle, extended to any red- and near-infrared-luminescent cell-probes and is fully compatible with quantum sensing measurements in living cells.

Adaptive changes induced by noble-metal nanostructures in vitro and in vivo

The unique features of noble-metal nanostructures (NMNs) are leading to unprecedented expansion of research and exploration of their application in therapeutics, diagnostics and bioimaging fields. With the ever-growing applications of NMNs, both therapeutic and environmental NMNs are likely to be exposed to tissues and organs, requiring careful studies towards their biological effects in vitro and in vivo. Upon NMNs exposure, tissues and cells may undergo a series of adaptive changes both in morphology and function. At the cellular level, the accumulation of NMNs in various subcellular organelles including lysosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, and nucleus may interfere with their functions, causing changes in a variety of cellular functions, such as digestion, protein synthesis and secretion, energy metabolism, mitochondrial respiration, and proliferation. In animals, retention of NMNs in metabolic-, respiratory-, immune-related, and other organs can trigger significant physiological and pathological changes to these organs and influence their functions. Exploring how NMNs interact with tissues and cells and the underlying mechanisms are of vital importance for their future applications. Here, we illustrate the characteristics of NMNs-induced adaptive changes both in vitro and in vivo. Potential strategies in the design of NMNs are also discussed to take advantage of beneficial adaptive changes and avoid unfavorable changes for the proper implementation of these nanoplatforms.

Gold nanourchins induce cellular stress, impair proteostasis and damage RNA

Gold nanoparticles have excellent potential for theranostic applications, but their impact on living cells is only partially understood. Many gold nanoparticles enter cells through endosomes/lysosomes which are linked to different cell organelles and compartments. Our study focuses on the unfolded protein response (UPR) in the endoplasmic reticulum (ER), cytoplasmic RNA-granules and proteostasis, because they are established indicators of cell stress and key regulators of cellular homeostasis. Using HeLa and renal proximal tubule cells as model systems, we show that gold nanourchins reduce cell proliferation, cause ER stress and impair proteostasis. Specifically, gold nanourchins activate the PERK-branch of the UPR, promote RNA oxidation, enhance P-body formation, and accumulate the oxidative stress marker Nrf2 and NFκB in nuclei. Taken together, our study demonstrates that gold nanourchins compromise ER, redox, protein, and RNA homeostasis. These insights provide new information on the cellular responses and molecular changes that gold nanourchins elicit in mammalian cells.

Gold nanoparticle uptake is enhanced by estradiol in MCF-7 breast cancer cells

Purpose: In the present study, we investigated the effects of 17β-estradiol (E₂) on membrane roughness and gold nanoparticle (AuNP) uptake in MCF-7 breast cancer cells. Methods: Estrogen receptor (ER)-positive breast cancer cells (MCF-7) were exposed to bare 20 nm AuNPs in the presence and absence of 1×10^-9 M E₂ for different time intervals for up to 24 hrs. The effects of AuNP incorporation and E₂ incubation on the MCF-7 cell surface roughness were measured using atomic force microscopy (AFM). Endocytic vesicle formation was studied using confocal laser scanning microscopy (CLSM). Finally, the results were confirmed by hyperspectral optical microscopy. Results: High-resolution AFM images of the surfaces of MCF-7 membranes (up to 250 nm²) were obtained. The incubation of cells for 12 hrs with AuNP and E₂ increased the cell membrane roughness by 95% and 30% compared with the groups treated with vehicle (ethanol) or AuNPs only, respectively. This effect was blocked by an ER antagonist (7α,17β-[9-[(4,4,5,5,5-Pentafluoropentyl)sulfinyl]nonyl]estra-1,3,5(10)-triene-3,17-diol [ICI] 182,780). Higher amounts of AuNPs were localized inside MCF-7 cells around the nucleus, even after 6 hrs of E₂ incubation, compared with vehicle-treated cells. Endolysosome formation was induced by E₂, which may be associated with an increase in AuNP-uptake. Conclusions: E₂ enhances AuNP incorporation in MCF-7 cells by modulating of plasma membrane roughness and inducing lysosomal endocytosis. These findings provide new insights into combined nanotherapies and hormone therapies for breast cancer.

Cellular senescence is associated with reorganization of the microtubule cytoskeleton

Senescent cells undergo structural and functional changes that affect essentially every aspect of cell physiology. To date, the impact of senescence on the cytoskeleton is poorly understood. This study evaluated the cytoskeleton in two independent cellular models of kidney epithelium senescence. Our work identified multiple senescence-related alterations that impact microtubules and filamentous actin during interphase. Both filamentous systems reorganized profoundly when cells became senescent. As such, microtubule stability increased during senescence, making these filaments more resistant to disassembly in the cold or by nocodazole. Microtubule stabilization was accompanied by enhanced α-tubulin acetylation on lysine 40 and the depletion of HDAC6, the major deacetylase for α-tubulin lysine 40. Rho-associated kinase Rock1 is an upstream regulator that modulates key properties of the cytoplasmic cytoskeleton. Our research shows that Rock1 concentrations were reduced significantly in senescent cells, and we revealed a mechanistic link between microtubule stabilization and Rock1 depletion. Thus, Rock1 overexpression partially restored the cold sensitivity of microtubules in cells undergoing senescence. Additional components relevant to microtubules were affected by senescence. Specifically, we uncovered the senescence-related loss of the microtubule nucleating protein γ-tubulin and aberrant formation of γ-tubulin foci. Concomitant with the alterations of microtubule and actin filaments, senescent cells displayed functional changes. In particular, cell migration was impaired significantly in senescent cells. Taken together, our study identified new senescence-associated deficiencies of the microtubule and actin cytoskeleton, provided insights into the underlying molecular mechanisms and demonstrated functional consequences that are important to the physiology and function of renal epithelial cells.

Analytical methodology for studying cellular uptake, processing and localization of gold nanoparticles

Interactions of gold nanoparticles (AuNPs) with live cells are known to exert a great impact on their functions, including cell signalling, genomic, proteomic, and metabolomic processes. Modern analytical techniques applied to studying nanoparticle-cell interactions are to improve our understanding of the mode of action of AuNPs, which is essential for their approval in disease therapeutics. Such methods may vary depending on what step of particle internalization is in question, i.e., cellular uptake, intracellular transport (accompanying by changes in the chemical state), translocation to different cell compartments, interaction with relevant subcellular structures and localization. This review focuses on the implementation and critical assessment of advanced analytical methodologies to investigate the cellular processing of AuNPs. Also addressed is a sought-after issue of accounting in in-vitro studies for a chemical form in which the AuNPs enter the cell in vivo.

The effects of lanthanide-doped upconverting nanoparticles on cancer cell biomarkers

Lanthanide-doped upconverting nanoparticles (Ln-UCNPs) possess optical and physicochemical properties that are promising for the design of new theranostic platforms. This applies in particular to the treatment of cancer. Towards this goal, oleate-capped-NaLuF4:Tm3+(0.5%)/Yb3+(20%)/Gd3+(30%) with an average size of 35 nm ± 2 nm were synthesized by co-precipitation. Due to their hydrophobic surface, these Ln-UCNPs produced agglomerates under cell culture conditions. To assess the cellular response to Ln-UCNPs at the molecular level, we evaluated several key aspects of tumor cell physiology. Using cancer lines of different origins, we demonstrated Ln-UCNP dependent changes of cancer cell biomarkers. Multiple cellular components that regulate tumorigenesis and cancer cell homeostasis were affected. In particular, Ln-UCNPs reduced the abundance of hsp70s, elevated DNA damage, and diminished nucleolin and B23/nucleophosmin, proteins required for the assembly of ribosomes. Treatment with Ln-UCNPs also decreased the concentration of paxillin, a focal adhesion protein that is involved in directed cell migration. Furthermore, epidermal growth factor (EGFR) levels were decreased by Ln-UCNPs for most cancer cell lines examined. Taken together, we identified several potential cancer cell targets that were affected by Ln-UCNPs. Our work thereby provides the foundation to optimize Ln-UCNPs for the targeted killing of tumor cells.

Gold nanoparticles: A plausible tool to combat neurological bacterial infections in humans

Management of bacterial infections of central nervous system is a major challenge for the scientists all over the world. Despite the development of various potential drugs, the issue of central nervous system infections persists in the society. The main constraint is the delivery of drugs across the blood brain barrier and only a few drugs after meeting the stringent criteria could cross the blood brain barrier. On the other hand, certain bacterial pathogens could easily enter the brain by using several factors and mechanisms by crossing the blood brain barriers. Interestingly, in the recent past, gold nanoparticles have shown immense potential to overcome the issues associated with the treatment of central nervous system infections, especially due to their inherent ability to cross the blood brain barrier. Initially, the present review summarized the recent updates on the pathogenesis and factors involved in neurological bacterial infections, including the mechanism used by bacterial pathogens to cross the blood brain barriers. Thereafter, the emphasis of the review was on providing current information on gold nanoparticles pertinent to their applicability for the treatment of neurological infections. After discussing the background of neurological bacterial infections, the characteristic features, antibacterial properties, mechanisms of antibacterial action and ability to cross the blood brain barrier of gold nanoparticles have been summarized. Some of the features of gold nanoparticles that make them an ideal candidate for brain delivery are biocompatibity, stability, ability to get synthesized in different sizes with facile methods, surface affinity towards various functional groups, spontaneous crossing of blood brain barrier without applying any external field and most importantly, easy non-invasive tracing by CT imaging. The current updates on the development of gold nanoparticles based therapeutic strategies for the prevention and treatment of central nervous system infections have been discussed in the present study. However, further investigation would be required to translate these preclinical outcomes into clinical applications. Nevertheless, we could safely state that the information gathered and discussed in the present review would benefit the scientists working in the field of neuro-nanotechnology.

Novel Combination of Silver Nanoparticles and Carbon Nanotubes for Plasmonic Photo Thermal Therapy in Melanoma Cancer Model

Purpose: Plasmonic photo thermal therapy (PPTT) is a therapeutic method in which the photon energy is rapidly transformed into heat via a series of radiative and non-radiative phenomena to ablate cancer. Plasmonic NPs, such as silver NPs (Ag NPs), have considerable properties in optical absorbance. Furthermore, good thermal conductivity and cell penetration ability of carbon nanotubes (CNTs) could improve the efficacy of Ag NPs for PPTT. Decoration of the multi-walled carbon nanotubes (MWCNTs) with silver has been developed to enhance thermal conductivity of the MWCNT particles. Methods: The Ag NPs were decorated on the CNTs and the ability of these particles (CNT/Ag NPs) in reduction of melanoma tumor size after PTT was evaluated experimentally. For comparison, the PTT of silver nanorods (Ag NRs) and CNTs were investigated. The melanoma tumor was induced by injection of B16/F10 cell line to the inbred mice. Different NPs were injected into the tumors and then irradiated via laser diode (λ=670 nm, P=500 mW, and I= 3.5 W/cm²) at scheduled time. Results: Monitoring of tumor sizes showed that integration of CNTs with silver could enhance the optical absorption of CNTs and improve tumor destruction in PPTT technique. Conclusion: The CNT/Ag NPs could act as a potent agent in PPTT method in curing solid tumors.

In vitro outlook of gold nanoparticles in photo-thermal therapy: a literature review

Hyperthermia is an anti-cancer treatment in which the temperature of the malignant tumor is increased more than other adjacent normal tissues. Microwave, ultrasound, laser, and radiofrequency sources have been used for hyperthermia of cancerous tissues. In the past decade, near-infrared (NIR) laser for cancer therapy, known as photo-thermal therapy (PTT), was expanded in which the photo-sensitizer agent converts the light photon energy to heat. The heat following PTT can destroy cancer cells. There are some photo-sensitizer agents which have been used for PTT; however, owing to recent advances in nanotechnology, noble metal nanoparticles like gold (Au) nanoparticles (GNPs) have been used successfully in PTT. GNPs have some desirable specifications, including simple and controlled synthesis, small size, high level of biocompatibility, and surface plasmon resonance (SPR). The SPR effect of the GNPs increases the radiative properties like absorption and scattering; therefore, they can be used in PTT. In this article, we reviewed recent in vitro studies of PTT using GNPs in literature. At first, we focus on the physical properties of GNPs, their interaction with infrared radiation, and physical parameters governing the interaction of infrared radiation with the GNPs. Then, we review the passive and active targeting of GNPs using the different coating to induce the thermal damage in cancer cells using low-level laser PPT. The GNPs' cellular internalization into cancer cells is a challenge which is consequently considered. In this review, we also summarize the results of synergistic cancer therapy studies on the combination of radiation therapy as a routine cancer treatment and PTT: in which significant improvement occurs in treatment efficacy.

Gold nanourchins and celastrol reorganize the nucleo- and cytoskeleton of glioblastoma cells

The physicochemical properties and cytotoxicity of diverse gold nanoparticle (AuNP) morphologies with smooth surfaces have been examined extensively. Much less is known about AuNPs with irregular surfaces. This study focuses on the effects of gold nanourchins in glioblastoma cells. With limited success of monotherapies for glioblastoma, multimodal treatment has become the preferred regimen. One possible example for such future therapeutic applications is the combination of AuNPs with the natural cytotoxic agent celastrol. Here, we used complementary physical, chemical and biological methods to characterize AuNPs and investigate their impact on glioblastoma cells. Our results show that gold nanourchins altered glioblastoma cell morphology and reorganized the nucleo- and cytoskeleton. These changes were dependent on gold nanourchin surface modification. PEGylated nanourchins had no significant effect on glioblastoma cell morphology or viability, unless they were combined with celastrol. By contrast, CTAB-nanourchins adversely affected the nuclear lamina, microtubules and filamentous actin. These alterations correlated with significant glioblastoma cell death. We identified several mechanisms that contributed to the impact of AuNPs on the cytoskeleton and cell survival. Specifically, CTAB-nanourchins caused a significant increase in the abundance of Rock1. This protein kinase is a key regulator of the cytoskeleton. In addition, CTAB-nanourchins led to a marked decline in pro-survival signaling via the PI3 kinase-Akt pathway. Taken together, our study provides new insights into the molecular pathways and structural components altered by gold nanourchins and their implications for multimodal glioblastoma therapy.

Toward a systematic exploration of nano-bio interactions

Many studies of nanomaterials make non-systematic alterations of nanoparticle physicochemical properties. Given the immense size of the property space for nanomaterials, such approaches are not very useful in elucidating fundamental relationships between inherent physicochemical properties of these materials and their interactions with, and effects on, biological systems. Data driven artificial intelligence methods such as machine learning algorithms have proven highly effective in generating models with good predictivity and some degree of interpretability. They can provide a viable method of reducing or eliminating animal testing. However, careful experimental design with the modelling of the results in mind is a proven and efficient way of exploring large materials spaces. This approach, coupled with high speed automated experimental synthesis and characterization technologies now appearing, is the fastest route to developing models that regulatory bodies may find useful. We advocate greatly increased focus on systematic modification of physicochemical properties of nanoparticles combined with comprehensive biological evaluation and computational analysis. This is essential to obtain better mechanistic understanding of nano-bio interactions, and to derive quantitatively predictive and robust models for the properties of nanomaterials that have useful domains of applicability.

Plasmonic/Magnetic Multifunctional nanoplatform for Cancer Theranostics

A multifunctional magneto-plasmonic CoFe2O4@Au core-shell nanoparticle was developed by iterative-seeding based method. This nanocargo consists of a cobalt ferrite kernel as a core (Nk) and multiple layers of gold as a functionalizable active stratum, (named as Nk@A after fifth iteration). Nk@A helps in augmenting the physiological stability and enhancing surface plasmon resonance (SPR) property. The targeted delivery of Doxorubicin using Nk@A as a nanopayload is demonstrated in this report. The drug release profile followed first order rate kinetics optimally at pH 5.4, which is considered as an endosomal pH of cells. The cellular MR imaging showed that Nk@A is an efficient T2 contrast agent for both L6 (r2-118.08 mM-1s-1) and Hep2 (r2-217.24 mM-1s-1) cells. Microwave based magnetic hyperthermia studies exhibited an augmentation in the temperature due to the transformation of radiation energy into heat at 2.45 GHz. There was an enhancement in cancer cell cytotoxicity when hyperthermia combined with chemotherapy. Hence, this single nanoplatform can deliver 3-pronged theranostic applications viz., targeted drug-delivery, T2 MR imaging and hyperthermia.

Increasing roughness of the human breast cancer cell membrane through incorporation of gold nanoparticles

Gold nanoparticles (AuNPs) have been proposed for use in the treatment of different types of cancer, including breast cancer. At present, neither the mechanisms of AuNP interaction with the plasma membrane surface and their delivery and intracellular distribution in cancer cells nor their effect on the plasma membrane so as to allow cell incorporation of larger amounts of AuNPs is known. The objective of this work was to study the interaction of bare 20 nm diameter AuNPs with the plasma membrane of human MCF-7 breast cancer cells, as well as their uptake, intracellular distribution, and induction of changes on the cell surface roughness. The dynamics of intracellular incorporation and the distribution of AuNPs were observed by confocal laser scanning microscopy. Changes in roughness were monitored in synchronized MCF-7 cells by atomic force microscopy high-resolution imaging at 6 hour intervals for 24 hours during a single cell cycle. The results show that bare AuNPs are capable of emitting fluorescence at 626 nm, without the need for a fluorescent biomarker, which allows monitoring their uptake and intracellular distribution until they reach the nucleus. These results are correlated with changes in cell roughness, which significantly increases at 12 hours of incubation with AuNPs, when compared with control cells. The obtained data provide bases to understand molecular processes of the use of AuNPs in the treatment of different diseases, mainly breast cancer.

Treatment of natural mammary gland tumors in canines and felines using gold nanorods-assisted plasmonic photothermal therapy to induce tumor apoptosis

Plasmonic photothermal therapy (PPTT) is a cancer therapy in which gold nanorods are injected at the site of a tumor before near-infrared light is transiently applied to the tumor causing localized cell death. Previously, PPTT studies have been carried out on xenograft mice models. Herein, we report a study showing the feasibility of PPTT as applied to natural tumors in the mammary glands of dogs and cats, which more realistically represent their human equivalents at the molecular level. We optimized a regime of three low PPTT doses at 2-week intervals that ablated tumors mainly via apoptosis in 13 natural mammary gland tumors from seven animals. Histopathology, X-ray, blood profiles, and comprehensive examinations were used for both the diagnosis and the evaluation of tumor statuses before and after treatment. Histopathology results showed an obvious reduction in the cancer grade shortly after the first treatment and a complete regression after the third treatment. Blood tests showed no obvious change in liver and kidney functions. Similarly, X-ray diffraction showed no metastasis after 1 year of treatment. In conclusion, our study suggests the feasibility of applying the gold nanorods-PPTT on natural tumors in dogs and cats without any relapse or toxicity effects after 1 year of treatment.

Zinc oxide nanoparticles-induced epigenetic change and G2/M arrest are associated with apoptosis in human epidermal keratinocytes

As an engineered nanomaterial, zinc oxide nanoparticles (ZnO NPs) are used frequently in biological applications and can make contact with human skin. Here, we systematically investigated the effects of ZnO NPs on non-tumorigenic human epidermal keratinocytes, which were used as a test model for this in vitro study, at the epigenetic and molecular levels. Our results showed that ZnO NPs induced cell cycle arrest at the G2/M checkpoint before the viability of human epidermal keratinocytes was reduced, which was associated with the chromatin changes at the epigenetic level, including increased methylation of histone H3K9 and decreased acetylation of histone H4K5 accompanied by chromatin condensation at 24 hours. The mRNA expression of the methyltransferase genes G9a and GLP was also increased upon treatment with ZnO NPs, and the acetyltransferase genes GCN5, P300, and CBP were downregulated. Reactive oxygen species were found to be more abundant after treatment with ZnO NPs for 6 hours, and DNA damage was observed at 24 hours. Transmission electron microscopy and flow cytometry confirmed that ZnO NPs were absorbed into the cell when they were added to the medium. Apoptotic human epidermal keratinocytes were detected, and the expression of the proapoptotic genes Bax, Noxa, and Puma increased significantly, while the expression of the antiapoptotic gene Bcl-xl decreased 24 hours after exposure to ZnO NPs. These findings suggest that the ZnO NPs induced cell cycle arrest at G2/M, which was associated with epigenetic changes and accompanied by p53-Bax mitochondrial pathway-mediated apoptosis.

An evaluation of in vitro intestinal absorption of iron, calcium and potassium in chickens receiving gold nanoparticles

This study evaluated the effect of oral administration of colloidal gold nanoparticles on accumulation of gold in the small intestine and intestinal absorption of iron, calcium and potassium under in vitro conditions. The gold nanoparticles are non-ionic, nanocrystalline, chemically pure particles 5 nm in size, produced in a physical process. In total, 126 one day-old Ross 308 chicks were assigned to 7 experimental groups of 18 birds each (3 replications of 6 individuals each). The control group (G-C) did not receive gold nanoparticles. Groups: Au-5(7), Au-10(7) and Au-15(7) received gold nanoparticles in their drinking water in the amounts of 5 mg l(-1) for group Au-5(7), 10 mg l(-1) for group Au-10(7) and 15 mg l(-1) for group Au-15(7) in 8-14, 22-28 and 36-42 d of life. The birds in groups Au-5(3), Au-10(3) and Au-15(3) received gold nanoparticles in the same amounts, but only in 8-10, 22-24 and 36-38 d of life. The study revealed that nanogold supplied via ingestion leads to dose- and time-dependent accumulation of gold in the intestinal walls. Nanogold present in the jejunum has a negative impact on the absorption of calcium, iron and potassium under in vitro conditions.

Noble Hybrid Nanostructures as Efficient Anti-Proliferative Platforms for Human Breast Cancer Cell

Nanomaterials have proven to possess great potential in biomaterials research. Recently, they have suggested considerable promise in cancer diagnosis and therapy. Among others, silicon (Si) nanomaterials have been extensively employed for various biomedical applications; however, the utilization of Si for cancer therapy has been limited to nanoparticles, and its potential as anticancer substrates has not been fully explored. Noble nanoparticles have also received considerable attention owing to unique anticancer properties to improve the efficiency of biomaterials for numerous biological applications. Nevertheless, immobilization and control over delivery of the nanoparticles have been challenge. Here, we develop hybrid nanoplatforms to efficiently hamper breast cancer cell adhesion and proliferation. Platforms are synthesized by femtosecond laser processing of Si into multiphase nanostructures, followed by sputter-coating with gold (Au)/gold-palladium (Au-Pd) nanoparticles. The performance of the developed platforms was then examined by exploring the response of normal fibroblast and metastatic breast cancer cells. Our results from the quantitative and qualitative analyses show a dramatic decrease in the number of breast cancer cells on the hybrid platform compared to untreated substrates. Whereas, fibroblast cells form stable adhesion with stretched and elongated cytoskeleton and actin filaments. The hybrid platforms perform as dual-acting cytophobic/cytostatic stages where Si nanostructures depress breast cancer cell adhesion while immobilized Au/Au-Pd nanoparticles are gradually released to affect any surviving cell on the nanostructures. The nanoparticles are believed to be taken up by breast cancer cells via endocytosis, which subsequently alter the cell nucleus and may cause cell death. The findings suggest that the density of nanostructures and concentration of coated nanoparticles play critical roles on cytophobic/cytostatic properties of the platforms on human breast cancer cells while having no or even cytophilic effects on fibroblast cells. Because of the remarkable contrary responses of normal and cancer cells to the proposed platform, we envision that it will provide novel applications in cancer research.

Gold Nanoparticles Impinge on Nucleoli and the Stress Response in MCF7 Breast Cancer Cells

Cancer cells can take up gold nanoparticles of different morphologies. These particles interact with the plasma membrane and often travel to intracellular organelles. Among organelles, the nucleus is especially susceptible to the damage that is inflicted by gold nanoparticles. Located inside the nucleus, nucleoli are specialized compartments that transcribe ribosomal RNA genes, produce ribosomes and function as cellular stress sensors. Nucleoli are particularly prone to gold nanoparticle-induced injury. As such, small spherical gold nanoparticles and gold nanoflowers interfere with the transcription of ribosomal DNA. However, the underlying mechanisms are not fully understood. In this study, we examined the effects of gold nanoparticles on nucleolar proteins that are critical to ribosome biogenesis and other cellular functions. We show that B23/nucleophosmin, a nucleolar protein that is tightly linked to cancer, is significantly affected by gold nanoparticles. Furthermore, gold nanoparticles impinge on the cellular stress response, as they reduce the abundance of the molecular chaperone hsp70 and O-GlcNAc modified proteins in the nucleus and nucleoli. Together, our studies set the stage for the development of nanomedicines that target the nucleolus to eradicate proliferating cancer cells.

Anti-HER2/neu peptide-conjugated iron oxide nanoparticles for targeted delivery of paclitaxel to breast cancer cells

Nanoparticles (NPs) for targeted therapy are required to have appropriate size, stability, drug loading and release profiles, and efficient targeting ligands. However, many of the existing NPs such as albumin, liposomes, polymers, gold NPs, etc. encounter size limit, toxicity and stability issues when loaded with drugs, fluorophores, and targeting ligands. Furthermore, antibodies are bulky and this can greatly affect the physicochemical properties of the NPs, whereas many small molecule-based targeting ligands lack specificity. Here, we report the utilization of biocompatible, biodegradable, small (∼30 nm) and stable iron oxide NPs (IONPs) for targeted delivery of paclitaxel (PTX) to HER2/neu positive breast cancer cells using an anti-HER2/neu peptide (AHNP) targeting ligand. We demonstrate the uniform size and high stability of these NPs in biological medium, their effective tumour targeting in live mice, as well as their efficient cellular targeting and selective killing in human HER2/neu-positive breast cancer cells.

Radiation Nanomedicine for EGFR-Positive Breast Cancer: Panitumumab-Modified Gold Nanoparticles Complexed to the β-Particle-Emitter, (177)Lu

Our objective was to construct a novel radiation nanomedicine for treatment of breast cancer (BC) expressing epidermal growth factor receptors (EGFR), particularly triple-negative tumors (TNBC). Gold nanoparticles (AuNP; 30 nm) were modified with polyethylene glycol (PEG) chains (4 kDa) derivatized with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelators for complexing the β-emitter, (177)Lu and with PEG chains (5 kDa) linked to panitumumab for targeting BC cells expressing EGFR. The AuNP were further coated with PEG chains (2 kDa) to stabilize the particles to aggregation. The binding and internalization of EGFR-targeted AuNP ((177)Lu-T-AuNP) into BC cells was studied and compared to nontargeted (177)Lu-NT-AuNP. The cytotoxicity of (177)Lu-T-AuNP and (177)Lu-NT-AuNP was measured in clonogenic assays using BC cells with widely different EGFR densities: MDA-MB-468 (10(6) receptors/cell), MDA-MB-231 (10(5) receptors/cell), and MCF-7 cells (10(4) receptors/cell). Radiation absorbed doses to the cell nucleus of MDA-MB-468 cells were estimated based on subcellular distribution. Darkfield and fluorescence microscopy as well as radioligand binding assays revealed that (177)Lu-T-AuNP were specifically bound by BC cells dependent on their EGFR density whereas the binding and internalization of (177)Lu-NT-AuNP was significantly lower. The affinity of binding of (177)Lu-T-AuNP to MDA-MB-468 cells was reduced by 2-fold compared to (123)I-labeled panitumumab (KD = 1.3 ± 0.2 nM vs 0.7 ± 0.4 nM, respectively). The cytotoxicity of (177)Lu-T-AuNP was dependent on the amount of radioactivity incubated with BC cells, their EGFR density and the radiosensitivity of the cells. The clonogenic survival (CS) of MDA-MB-468 cells overexpressing EGFR was reduced to <0.001% at the highest amount of (177)Lu-T-AuNP tested (4.5 MBq; 6 × 10(11) AuNP per 2.5 × 10(4)-1.2 × 10(5) cells). (177)Lu-T-AuNP were less effective for killing MDA-MB-231 cells or MCF-7 cells with moderate or low EGFR density (CS = 33.8 ± 1.6% and 25.8 ± 1.2%, respectively). Because the β-particles emitted by (177)Lu have a 2 mm range, (177)Lu-NT-AuNP were also cytotoxic to BC cells due to a cross-fire effect but (177)Lu-T-AuNP were significantly more potent for killing MDA-MB-468 cells overexpressing EGFR than (177)Lu-NT-AuNP at all amounts tested. The cross-fire effect of the β-particles emitted by (177)Lu may be valuable for eradicating BC cells in tumors that have low or moderate EGFR expression or cells that are not targeted by (177)Lu-T-AuNP as a consequence of heterogeneous intratumoral distribution. The radiation dose to the nucleus of a single MDA-MB-468 cell was 73.2 ± 6.7 Gy, whereas (177)Lu-NT-AuNP delivered 5.6 ± 0.6 Gy. We conclude that (177)Lu-T-AuNP is a promising novel radiation nanomedicine with potential application for treatment of TNBC, in which EGFR are often overexpressed.

Toxicity and Biokinetics of Colloidal Gold Nanoparticles

Gold nanoparticles (Au-NPs) have promising potential for diverse biological application, but it has not been completely determined whether Au-NP has potential toxicity in vitro and in vivo. In the present study, toxicity of Au-NP was evaluated in human intestinal cells as well as in rats after 14-day repeated oral administration. Biokinetic study was also performed to assess oral absorption and tissue distribution. The results demonstrated that Au-NP did not cause cytotoxic effects on cells after 24 h exposure in terms of inhibition of cell proliferation, membrane damage, and oxidative stress. However, when a small number of cells were exposed to Au-NP for seven days, colony forming ability remarkably decreased by Au-NP treatment, suggesting its potential toxicity after long-term exposure at high concentration. Biokinetic study revealed that Au-NP slowly entered the blood stream and slightly accumulated only in kidney after oral administration to rats. Whereas, orally administered Au ions were rapidly absorbed, and then distributed in kidney, liver, lung, and spleen at high levels, suggesting that the biological fate of Au-NP is primarily in nanoparticulate form, not in ionic Au. Fourteen-day repeated oral toxicity evaluation showed that Au-NP did not cause severe toxicity in rats based on histopathological, hematological, and serum biochemical analysis.

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.