Ultrasound activated microneedle with antibacterial nanoparticles for skin infections

June 23, 2023

(Nanowerk News) A team of researchers led by Professor Kelvin Yeung from Department of Orthopedics and Traumatology, Faculty of Clinical Medicine, LKS School of Medicine, University of Hong Kong (HKUMed) have designed a new microneedle patch to offer a highly effective non-antibiotic approach to the treatment of skin infections.

In summary, a design engineered with zinc-responsive zinc-based metal-organic framework antibacterial nanoparticles promises painless delivery to treat bacterial infections of skin tissue and facilitate skin repair at the same time. The new microneedles are about 50 microns in diameter, similar to normal hair.

These findings have been published in Science Advances (“Microneedle based on ultrasound-induced interface engineering for the treatment of acne due to bacterial infections”). Acne treatment via efficient ultrasound-triggered antibacterial microneedle embedded patch. (Image: HKUMed) (click image to enlarge)


Acne is a common skin disease worldwide that affects more than 80% of adolescents and young adults. 1 Its main cause can be attributed to excessive lipid secretion that clogs hair follicles, thereby creating a hypoxic microenvironment in skin tissues. This unfavorable condition primarily favors proliferation Propionibacterium acnes (P. acnes) bacteria. Infected acne, considered as one of the skin infections, is mainly caused by P. acnes bacteria that affect millions of people worldwide. This not only causes the patient significant physical and emotional distress, but can also develop into a chronic inflammatory condition without proper treatment. Clinical management usually includes over-the-counter medications (ie, benzoyl peroxide and salicylic acid), or oral or topical administration of antibiotics. However, such treatments can be ineffective or have unpleasant side effects.

In general, the first line of treatment for infected acne is the administration of antibiotics either orally or topically. However, the therapeutic effect of topical antibiotic treatment is of great concern, especially when the drug penetrates the skin tissue. Also, the treatment becomes less effective, when the bacteria are resistant to the drug or when they migrate to the subcutaneous tissue. Specifically, P. acnes Bacteria can secrete extracellular polysaccharides to form biofilms that block attacks initiated by antibacterial agents or immune cells.

In fact, most of the microneedle products on the market mostly use pharmaceutical ingredients to treat acne. However, repeated use of antibiotics can reduce the sensitivity of bacteria to drugs. Patients who have had acne for a long time will find that the effects of the same treatment product can be significantly reduced after prolonged use.

Research methods and findings

The HKUMed team has devised a new microneedle patch that facilitates transdermal delivery of ultrasound-responsive antibacterial nanoparticles to treat infections caused by P. acnes with a minimally invasive approach. In the current design, an ultrasound responsive antibacterial nano material is introduced to the microneedle patch which responds quickly and efficiently to bacterial infection. The use of drugs is avoided in the treatment of acne.

The modified nanoparticles composed of ZnTCPP and ZnO are capable of generating large amounts of reactive oxygen species (ROS) subject to ultrasound stimulation which can effectively oxidize major cellular macromolecules of bacteria. The results show that the killing of P. acnes bacteria mediated ROS can reach 99.73% after 15 minutes of ultrasound stimulation. Also, levels of inflammatory markers, including tumor necrosis factor-a (TNF-α), interleukins (ILs), and matrix metalloproteinases (MMPs) were significantly reduced. In addition, zinc ions released can increase DNA replication related genes, thereby adding more fibroblasts towards superior skin repair.

Research significance

Professor Kelvin Yeung Wai-kwok, commented, ‘The new microneedle patch which enables the formation of ROS through ultrasound stimulation, considered as a non-antibiotic and transdermal approach, can not only effectively tackle the infection caused by the bacterium P. acnes, but also facilitate the skin. improvement due to the release of zinc ions. Due to the specific killing mechanism of ROS, we believe that this design is also capable of dealing with other skin infections caused by fungi, parasites or viruses, such as tinea pedis (ie “Athlete’s Foot” or “Hong Kong Foot” in slang).’

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