In an article recently published in the open-access MDPI journal nanomaterials, researchers investigated the mechanism of interaction between nanoscale materials and specific cells for biomedical applications, primarily related to targeted delivery and tracing.
Here, the localization, cellular uptake quantity, and response time of gold nanorods in MCF-7 and SKBR-3 breast cancer cells were measured.
Background
The amalgamation of biotechnology and nanotechnology has been a quite fascinating field of research for the last few years.
Currently, nanomaterials are extensively used in biomedical applications such as drug delivery, magnetic or fluorescent bio-imaging, tissue engineering, tracing pathogens in sensitive organs, cancer chemotherapy, and many more. However, each nanomaterial interacts differently with a particular type of cell.
Many studies have shown cellular uptake of gold nanorods by cancer cells. MCF-7 and SKBR-3 cancer cell lines represent HER2-negative and HER2-positive breast cancer models, respectively. These cells intake gold nanorods through a mechanism occurring at the surface of the cell membrane, called endocytosis.
Inductively coupled plasma mass spectrometry (ICP-MS) can measure the efficiency of targeted delivery and cellular uptake of these nanoparticles, while transmission electron microscopy (TEM) can be used to investigate their localization.
Figure 1. Transmission electron microscope images of gold nanorods with aspect ratio around 3 at different magnifications (a–c). (d) UV–visible spectrum analysis of the prepared gold nanorods showing longitudinal and transverse plasmons around 690 nm and 514 nm, respectively. © White, B., White, M., Nima Alsudani, Z., Watanabe, F., Biris, A., Ali, N., (2022)
About the Study
In this article, researchers investigated the interaction mechanism of gold nanorods (Au NRs) in two types of breast cancer cell lines namely, MCF-7 and SKBR-3. More than 200 Au NRs with an average length and diameter of 36 and 12 nm, respectively, were synthesized using the silver ion-assisted seed-mediated method. Subsequently, MCF-7 and SKBR-3 cells were cultured in a conducive medium and allowed to bind with different concentrations of Au NRs for 1 and 2 days.
The excess Au NRs were washed away from the treated cancels using phosphate buffer saline (PBS) solution followed by treating with the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) reagent. Finally, ICP-MS and TEM analyses were performed to investigate the interaction mechanism.
Figure 2. TEM images of AuNRs in SKBR-3 cells at different time points and concentrations. SKBR-3 cells were treated with 5, 25, and 75 μg/mL of AuNRs for 1, 4, 24, and 48 h. Internalization of nanorods was observed starting at 4hourincubation with 75 μg/mL (a). After 24hourof incubation, internalization was observed with the 25 μg/mL (b) and 75 μg/mL concentrations (c). For cells incubated for 48 h, we observed internalization with 5, 25, and 75 μg/mL concentrations (d, e, and f, respectively). Red arrows point to gold nanorods localized in SKBR-3 cells. Electron photomicrographs shown are representative of at least three independent experiments with similar conditions. © White, B., White, M., Nima Alsudani, Z., Watanabe, F., Biris, A., Ali, N., (2022)
Observations
TEM images showed Au NRs had longitudinal and transverse plasmon resonances at around 680 and 514 nm, respectively. The average zeta potential of the NRs was −47.18 ± 4.26 mV. Au NRs did not show any cytotoxicity in healthy human cells. MTT methods indicated that the MCF-7 cells were less sensitive to Au NR exposure than the SKBR-3 cells for longer exposure times at higher concentrations. The SKBR-3 cells exhibited a drop in cell vitality due to higher sensitivity, whereas the MCF-7 cells had almost no drop in cell viability.
Both types of cells demonstrated a different pattern in cellular uptake of Au NRs for different exposure times and concentrations. The SKBR-3 cells had a constant cellular uptake between one to four hours, but 25 μg/mL Au NRs concentration had a higher uptake than the 75 μg/mL sample, i.e. lower concentration had a higher cellular uptake. In contrast, in MCF-7 cells, the 75 μg/mL AuNR-treated cell samples exhibited higher cellular uptake than 5 and 25 μg/mL samples, i.e. higher concentration samples had higher cellular uptake than lower concentration samples.
Furthermore, TEM analysis showed that the Au NRs interacted with the cell membrane of both cancer cells starting from one to 48 hours of exposure time. However, the Au NRs entered into the cell (i.e. internalized) for the samples with concentrations of 25 and 75 μg/mL. The 5 μg/mL concentration samples were never internalized. Moreover, the minimum exposure time for internalization was one hour and four hours for the MCF-7 and SKBR-3 cells, respectively.
The mechanism for the cellular uptake of the Au NRs was primarily micropinocytosis instead of receptor-mediated endocytosis. These Au NRs-carrying macropinosomes further interacted with the lysosomes inside the cells.
Figure 3. TEM images showing localization of gold nanorods in macropinosomes and lysosomes in both SKBR-3 and MCF-7 cell lines. AuNR localization in (a) macropinosomes (MA) and (b) lysosomes (Ly) of SKBR-3 cells. (c) Macropinosomes (MA) containing gold nanorods in MCF-7 and (d) lysosomes (Ly) containing gold nanorods in MCF-7. Red arrows point out macropinosomes and lysosomes containing gold nanorods in each image. Electron photomicrographs shown are representative of at least three independent experiments with similar conditions. © White, B., White, M., Nima Alsudani, Z., Watanabe, F., Biris, A., Ali, N., (2022)
Conclusions
To conclude, the researchers of this study investigated the interaction of Au NRs in two types of breast cancer cell lines, i.e. MCF-7 and SKBR-3. The shape, size, and zeta potential of Au NRs had different effects on cell vitality and toxicity of different cancer cells. Additionally, both cell types had different patterns of cellular uptake for Au NRs at different concentrations and exposure times.
The Au NRs did not enter into the cancer cells for samples with lower concentrations of NRs or lower exposure time. Also, the cellular uptake mechanism was primarily driven by micropinocytosis. These findings will help improve biomedical applications related to targeted drug delivery, tracing, and bio-imaging involving nanomaterials.
![](https://www.nanoappsmedical.com/wp-content/uploads/2017/05/spacer.jpg)
News
The Silent Battle Within: How Your Organs Choose Between Mom and Dad’s Genes
Research reveals that selective expression of maternal or paternal X chromosomes varies by organ, driven by cellular competition. A new study published today (July 26) in Nature Genetics by the Lymphoid Development Group at the MRC [...]
Study identifies genes increasing risk of severe COVID-19
Whether or not a person becomes seriously ill with COVID-19 depends, among other things, on genetic factors. With this in mind, researchers from the University Hospital Bonn (UKB) and the University of Bonn, in [...]
Small regions of the brain can take micro-naps while the rest of the brain is awake and vice versa
Sleep and wake: They're totally distinct states of being that define the boundaries of our daily lives. For years, scientists have measured the difference between these instinctual brain processes by observing brain waves, with [...]
Redefining Consciousness: Small Regions of the Brain Can Take Micro-Naps While the Rest of the Brain Is Awake
The study broadly reveals how fast brain waves, previously overlooked, establish fundamental patterns of sleep and wakefulness. Scientists have developed a new method to analyze sleep and wake states by detecting ultra-fast neuronal activity [...]
AI Reveals Health Secrets Through Facial Temperature Mapping
Researchers have found that different facial temperatures correlate with chronic illnesses like diabetes and high blood pressure, and these can be detected using AI with thermal cameras. They highlight the potential of this technology [...]
Breakthrough in aging research: Blocking IL-11 extends lifespan and improves health in mice
In a recent study published in the journal Nature, a team of researchers used murine models and various pharmacological and genetic approaches to examine whether pro-inflammatory signaling involving interleukin (IL)-11, which activates signaling molecules such [...]
Promise for a universal influenza vaccine: Scientists validate theory using 1918 flu virus
New research led by Oregon Health & Science University reveals a promising approach to developing a universal influenza vaccine—a so-called "one and done" vaccine that confers lifetime immunity against an evolving virus. The study, [...]
New Projects Aim To Pioneer the Future of Neuroscience
One study will investigate the alterations in brain activity at the cellular level caused by psilocybin, the psychoactive substance found in “magic mushrooms.” How do neurons respond to the effects of magic mushrooms? What [...]
Decoding the Decline: Scientific Insights Into Long COVID’s Retreat
Research indicates a significant reduction in long COVID risk, largely due to vaccination and the virus’s evolution. The study analyzes data from over 441,000 veterans, showing lower rates of long COVID among vaccinated individuals compared [...]
Silicon Transformed: A Breakthrough in Laser Nanofabrication
A new method enables precise nanofabrication inside silicon using spatial light modulation and laser pulses, creating advanced nanostructures for potential use in electronics and photonics. Silicon, the cornerstone of modern electronics, photovoltaics, and photonics, [...]
Caught in the actinium: New research could help design better cancer treatments
The element actinium was first discovered at the turn of the 20th century, but even now, nearly 125 years later, researchers still don't have a good grasp on the metal's chemistry. That's because actinium [...]
Innovative Light-Controlled Drugs Could Revolutionize Neuropathic Pain Treatment
A team of researchers from the Institute for Bioengineering of Catalonia (IBEC) has developed light-activated derivatives of the anti-epileptic drug carbamazepine to treat neuropathic pain. Light can be harnessed to target drugs to specific [...]
Green Gold: Turning E-Waste Into a Treasure Trove of Rare Earth Metals
Scientists are developing a process inspired by nature that efficiently recovers europium from old fluorescent lamps. The approach could lead to the long-awaited recycling of rare earth metals. A small molecule that naturally serves [...]
Cambridge Study: AI Chatbots Have an “Empathy Gap,” and It Could Be Dangerous
A new study suggests a framework for “Child Safe AI” in response to recent incidents showing that many children perceive chatbots as quasi-human and reliable. A study has indicated that AI chatbots often exhibit [...]
Nanoparticle-based delivery system could offer treatment for diabetics with rare insulin allergy
Up to 3% of people with diabetes have an allergic reaction to insulin. A team at Forschungszentrum Jülich has now studied a method that could be used to deliver the active substance into the [...]
Nanorobot kills cancer cells in mice with hidden weapon
Researchers at Karolinska Institutet in Sweden have developed nanorobots that kill cancer cells in mice. The robot's weapon is hidden in a nanostructure and is exposed only in the tumor microenvironment, sparing healthy cells. [...]