The Centers for Disease Control and Prevention estimates that more than 2.8 million Americans experience antibiotic-resistant infections each year; more than 35,000 die from those infections.
The study, “Hydrophilic Nanoparticles that Kill Bacteria while Sparing Mammalian Cells Reveal the Antibiotic Role of Nanostructures,” was published Jan. 11 by Nature Communications.
Past research has shown that hydrophobicity (a molecule’s ability to repel water) and hydrophilicity (a molecule’s ability to attract and dissolve in water) affects cells; the more hydrophobic a substance is, the more adverse the reaction it will cause. However, Liang said, there is no quantitative standard for how much hydrophobicity is acceptable.
“Basically, you can kill bacteria when you increase hydrophobicity,” Liang said. “But it will also kill healthy cells, and we don’t want that.”
For their study, the Liang team used novel hydrophilic nanoparticles known as nanoantibiotics that were developed by Liang’s laboratory. Structurally speaking, these novel nanoantibiotics resemble tiny hairy spheres, each composed of many hydrophilic polymer brushes grafted onto silica nanoparticles of different sizes.
These synthetic compounds, which Liang’s lab produces, are designed to kill bacteria via membrane disruptions like antimicrobial peptides do, but through a different mode of membrane remodeling that damages bacterial membranes and not mammalian cells. Antimicrobial peptides are a diverse class of amphipathic molecules (partially hydrophilic-partially hydrophobic), which occur naturally and serve as the first line of defense for all multicellular organisms. The direct use of antimicrobial peptides as antibiotics is limited by their stability and toxicity.
There have been other studies in which researchers grafted amphipathic molecules onto nanoparticles, and they too kill bacteria. However, Liang said the primary issue in using amphipathic molecules is that it becomes very difficult to strike the right balance between their hydrophobicity and hydrophilicity so that the toxicity of these molecules to our own cells is significantly reduced.
“In our case, we remove that uncertainty from the equation because we started with a hydrophilic polymer,” Liang pointed out. “The cytotoxicity of hydrophobic moieties is not a concern anymore. Those hydrophilic polymers by themselves, or the silica nanoparticles alone don’t kill bacteria; they have to be grafted onto the nanostructure to be able to kill bacteria. And so, this is the first important discovery.”
The Liang team also discovered that the degree of antibiotic activity is affected by the size of the hairy spheres, which according to Liang is the second important discovery of this research. Those measuring 50 nanometers and below appear to be much more active than those whose size exceeds 50 nanometers. Liang said those measuring approximately 10 nanometers appear to be the most active. (Using synchrotron small angle X-ray scattering and other methods, the Liang team is able to interpret the molecular mechanism of the size-dependent antibiotic activity.)
These discoveries are important because using nanoantibiotics to kill bacteria evades all known mechanisms of bacterial resistance unless bacteria completely revamp their pathways for making cell membranes, which Liang said is unlikely.
“It is also nearly impossible for bacteria to develop new resistance against the nanoantibiotics,” Liang emphasized. “Furthermore, this discovery illuminates a blueprint to develop new antibiotics that would kill bacteria upon contact, but remain amiable to humans because they are produced using non-toxic and environmentally friendly ingredients via nanoengineering.”
News
What is ‘American Covid’ and how bad is it?
Cases of so-called ‘American Covid’ are on the rise in the UK. The strain is officially called XFG, or ‘Stratus’, and is the most common variant in North America, hence the name. It might soon [...]
Researcher at Russian plague laboratory dies of ‘unknown’ infection
Russian authorities have imposed "anti-epidemic measures" after a laboratory worker at an institute in Siberia dedicated to studying the plague and other infectious diseases died of a mysterious illness. The researcher, a 28-year-old female [...]
GHCE Concept
From the preface of the book Global Health Care Equivalency in the Age of Nanotechnology, Nanomedicine and Artificial Intelligence, Edited by Frank Boehm: Since the publication of my first book (Nanomedical Device and Systems [...]
A Surprising Brain Signal Could Explain Why Eating Less Protein Extends Lifespan
A new paper suggests that limiting protein intake triggers a coordinated response throughout the body that may help explain how protein restriction affects healthy aging. Animals respond to protein restriction, or reduced protein in [...]
Back and shoulder surgery is often worse than useless
Millions of operations should be scrapped SIX IN TEN Britons have surgery at some point. So do lots of Americans, at a cost of perhaps $500bn a year, a third of all spending on [...]
Cocaine plays with mind, hijacks brain circuit, drives increasingly rigid and repetitive behavior
Researchers have found that cocaine hijacks brain circuit, which to drive increasingly rigid and repetitive behavior. The brain circuit that normally participates in selecting natural mouth and face movements, but which becomes disproportionately engaged [...]
Injectable nanodevices could provide effective treatment for drug-resistant glioblastoma
The brain cancer glioblastoma is one of the most aggressive and treatment-resistant cancers known to medicine, carrying a median survival of just 12-15 months, even with the best available care. Now, researchers at the [...]
New Treatment Cuts “Bad” Cholesterol in Half for a Full Year
A single infusion of an experimental CRISPR-Cas9 therapy was reported to safely lower LDL cholesterol by 52.5% and triglycerides by 47.8%, as measured 12 months after treatment. What if one infusion could keep cholesterol [...]
Too Much RNA Can Drain a Cell’s Energy, Scientists Discover
A virus may cripple a cell’s power supply simply by producing too much of a molecule the cell needs to survive. New research from the Texas A&M College of Veterinary Medicine and Biomedical Sciences [...]
West African scientists warn of weakening health systems and urge stronger outbreak detection
LOME, Togo (AP) — West African laboratory scientists called on governments Friday to strengthen capacity to detect disease outbreaks to avoid another major outbreak, saying health systems across the region are becoming weaker. Participants [...]
A Little-Known Protein Could Point to a New Way To Treat Alzheimer’s
A study suggests that increasing SORLA protein levels could help treat Alzheimer’s disease and other disorders involving tau protein. Increasing SORLA, a protein with a protective role in the brain, helped mice withstand damage [...]
Cancer’s Hidden Antioxidant Shield Helps It Escape the Immune System
Blocking an antioxidant protein that tumors use to suppress immune attacks improved cancer immunotherapy responses in mice. Cancer cells can release antioxidants that interfere with the immune cells trying to kill them. Researchers have [...]
Scientists Find a Berry Compound That Helps Muscle Cells Burn Fat
Pterostilbene, a compound found naturally in some foods, affects how skeletal muscles process fats by stabilizing a protein called PPARδ and increasing its signaling activity. Pterostilbene, a natural compound found in blueberries, grapes, and [...]
Two Hidden Forces Help Build the Human Brain Before Birth
Scientists have uncovered two surprising forces that help guide how the human brain forms before birth. Before birth, the human brain is shaped in large part by an unusual class of stem cells known [...]
Researchers Uncover a Hidden Trigger Behind Chronic Inflammation
The findings offer new insights that could help guide the development of future therapies. A protein called human resistin may help flip on one of the immune system’s most powerful inflammatory switches. Researchers at [...]
Scientists Have Uncovered Previously Hidden Microbial Activity on Human Skin
The most abundant microbes on your skin may not be the ones doing most of the work. Human skin supports vast communities of bacteria, fungi, and viruses that can influence its protective barrier, immune [...]
