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Poly-branched fluorescent imaging probes

Fluorescent smartprobes designed for real-time imaging of microbes in situ and ex vivo


  • Fluorescent detection of gram-positive and gram-negative bacteria and fungi
  • Further development of tri-branched dendrimers

Development Status

  • Validated in in vitro assays, microbial keratitis clinical samples and in explant human lungs
  • Intrathecal toxicology and GLP intravenous toxicology studies have been performed and highlighted no adverse effects on rodents

IP Status

  • Priority filed in 2014
  • Granted in US, pending in Europe
  • Claims in the US cover poly-branched probes

Commercial Offerings

  • Licensing


There is a growing burden of bacterial & fungal infections worldwide and accurate diagnosis remains a cornerstone to providing effective treatment. The development of optical molecular imaging smartprobes to detect bacteria or fungi in vivo in situ at the bedside would provide a paradigm changing technology to many aspects of infectious medicine. BAC ONE has been shown to detect bacteria and fungi in a number of diseases including pneumonia, cystic fibrosis and in corneal scrapes from patients with suspected microbial keratitis.

With broad patent protection in the US, there is also the opportunity to further develop these tri-branched dendrimer probes for your own applications.

Dendrimers have a range of potential applications in biology and medicine, including drug delivery, imaging, and gene therapy. In drug delivery, dendrimers can be used to target specific cells or tissues, increasing the efficiency and reducing the side effects of drugs. In imaging, dendrimers can be used as contrast agents to enhance the visibility of certain structures in the body. In gene therapy, dendrimers can be used to deliver genetic material to cells to correct genetic disorders. Dendrimers also have potential applications in materials science, electronics, and nanotechnology.

Technology Overview

BAC ONE is a modified tri-branched dendrimer based on an antimicrobial peptide (Ubiquicidin) scaffold, with each dendrimer coupled to a NBD fluorophore via a PEG linker.

NBD is an environmentally sensitive fluorophore, with excitation at 465nm and peak emission at 540nm. Its environmentally sensitive composition means its fluorescence will increase in the presence of a hydrophobic environment and remain optically silent out with these conditions. As the apolar bacterial/fungal membrane is a hydrophobic environment, the fluorescence signal will increase in the membrane and allow microbial identification.

In vitro assays have confirmed BAC ONE labels a range of bacterial strains including S. aureus, K. pneumoniae, P. aeruginosa, E. coli and H. influenzae, amongst others, as well as filamentous fungi Aspergillus spp and Fusarium spp. BAC ONE does not label mammalian cells and does not result in any membrane toxicity or architectural changes. Furthermore, studies have shown that BAC ONE can detect colonised bacteria in situ in pulmonary segments of ventilated ovine lungs and in whole explant cystic fibrosis human lungs. Bac One is also able to detect bacterial and fungal pathogens collected directly from the cornea of microbial keratitis patients, with equivalent or better sensitivity and specificity than current gold-standard diagnostic techniques.


  • Fast, fluorescent labelling of gram- positive and gram-negative bacteria, as well as fungi
  • Broad patent coverage (US granted) covering poly-branched probes, without restricting to specific fluorophores or linkers or binding moieties
  • A single dose intratracheal instillation toxicology study and a repeat dose GLP IV toxicology package has been performed in rodents with no findings observed


Gunasekaran, R., Lalitha, P., Megia-Fernandez, A., Bradley, M., Williams, R. L., Dhaliwal, K., ... & Mills, B. (2020). Exploratory use of fluorescent SmartProbes for the rapid detection of microbial isolates causing corneal ulcer. American journal of ophthalmology, 219, 341-350.

Akram, A. R., Avlonitis, N., Scholefield, E., Vendrell, M., McDonald, N., Aslam, T., ... & Dhaliwal, K. (2019). Enhanced avidity from a multivalent fluorescent antimicrobial peptide enables pathogen detection in a human lung model. Scientific reports, 9(1), 1-10.

Akram, A. R., Avlonitis, N., Lilienkampf, A., Perez-Lopez, A. M., McDonald, N., Chankeshwara, S. V., ... & Dhaliwal, K. (2015). A labelled-ubiquicidin antimicrobial peptide for immediate in situ optical detection of live bacteria in human alveolar lung tissue. Chemical Science, 6(12), 6971-6979.

Header image: Catalin/Adobe Stock

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Emily Thompson

Technology Transfer Manager
Edinburgh Innovations Ltd
The University of Edinburgh