RSC Advances Blog

We are very pleased to introduce Dr Abdu Saeed who is the corresponding author of the RSC Advances article, antibacterial activity of the micro and nanostructures of the optical material tris(8-hydroxyquinoline)aluminum and its application as an antimicrobial coating. This was well received by reviewers and was handpicked by our handling editors to be part of our Popular Advances collection – a big congratulations to all the authors!

Dr Saeed told us more about the work that went into this study and what he hopes to achieve in the future. You can explore other articles in our 2022 Popular Advances online collection here!

Meet the Author:

Abdu Saeed was born in Ibb, Yemen, in 1979. After obtaining two degrees in physics (from Ibb University and Taiz University, respectively) he was selected as a teaching assistant at Thamar University. Afterwards, he pursued an MSc and PhD in applied experimental physics at King Abdulaziz University, Saudia Arabia, where he was selected as the best postgraduate student! Nowadays, Dr Saeed works in multidisciplinary fields including energy, electrical properties, nanotechnology, and polymer science. Currently, Dr Saeed and his group are studying the bio applications of the optical material tris(8-hydroxyquinoline)aluminum.

Could you briefly explain the focus of your article to the non-specialist and why it is of current interest?
This research focuses mainly on estimating the antibacterial activity of Alq3, but the effect of particle size (micro- and nano- structures) of the Alq3 powders was also investigated. Furthermore, we successfully incorporated this material with polystyrene to form an antibacterial composite for coating purposes.

How big an impact could your results potentially have?
Alq3 is one of the most famous small molecular semiconductors with efficient electroluminescence and fluorescence properties. Since this material was used to manufacture the first OLED, it has been utilized massively in fabricating optoelectrical devices. However, it has not been used in bio applications. Therefore, we think use as an antibacterial coating could bring more interest to Alq3 in bio applications. 

Could you explain the motivation behind this study?
I was studying the toxicity of this material and found two things: Firstly, this material has high toxicity and, when used as a dye for fluorescence bioimaging, the captured images had high fluorescence. These results gave the motivation to utilize this material in new bio applications. Secondly, we spent three months overcoming bacterial contamination in the lab while doing the cell viability experiments. These two things motivated us to study whether Alq3 can be used as an antibacterial agent.

In your opinion, what are the key design considerations for your study?
Alq3 is an attractive and exciting material. It has different crystal structures, and it is considered the most popular organometallic semiconductor in OLED. Its molecular structure has a conjugated π-electron system, which is advantageous for many applications. This material has electroluminescence (EL) and photoluminescence (PL) properties. EL properties make it an excellent material for optoelectronics devices; PL properties make it a good material for optical applications. Its diverse properties and current applications make it an excellent candidate for more investigations into new applications.

Which part of the work towards this paper proved to be most challenging?
We tested the antibacterial activity of the Alq3 samples on seven different human pathogenic bacterial strains representing Gram-positive and Gram-negative bacteria: Escherichia coli ATCC 11775 (EC), Enterococcus faecalis ATCC 29212 (EF), Klebsiella pneumoniae ATCC 13883 (KP), Methicillin-resistant Staphylococcus aureus ATCC 33591 (MRSA), Pseudomonas aeruginosa ATCC 9027 (PA), Staphylococcus aureus ATCC 12600 (SA), and Salmonella Typhimurium ATCC 14028 (ST). Estimating the IC50 for this material against the bacterial strains was the most challenging part of this study.

What aspect of your work are you most excited about at the moment?
We are most excited about using Alq3 in biosensor applications, particularly in bioimaging. We believe that it will be interesting to make modifications, such as using an appropriate material as a surface modifier containing optimized ligands to synthesize Alq3 into a core-shell form. This could further reduce Alq3’s toxicity whilst maintaining its impressive fluorescence.

What is the next step? What work is planned?
We will use what we have achieved to identify and obtain further uses for Alq3. We will study its antifungal activity and incorporate it with suitable polymers for its antifungal tests. Additionally, we hope to check its interaction with different viruses. The first use of Alq3 for bioimaging was by us – we believe there is still much more effort to be made to optimize the use of Alq3 in bioimaging. 

Antibacterial activity of the micro and nanostructures of the optical material tris(8-hydroxyquinoline)aluminum and its application as an antimicrobial coating

Abdu Saeed, Aysh Y. Madkhli, Rami Adel Pashameah, Noor M. Bataweel, Mir Ali Razvi and Numan Salah

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We are excited to introduce Dr James Knight, who is the corresponding author of the RSC Advances article, The influence of degree of labelling upon cellular internalisation of antibody-cell penetrating peptide conjugates. The manuscript was well received by reviewers and was handpicked by our handling editors to be part of our Popular Advances collection.

Dr Knight told us more about the work that went into this paper and what he hopes to achieve in the future. You can explore other articles in our 2022 Popular Advances online collection here!

Meet the Author:

Dr James Knight is lecturer in radiochemistry at the School of Natural and Environmental Sciences at Newcastle University. His research surrounds the synthesis and preclinical evaluation of radiopharmaceuticals for imaging and therapeutic applications. Additionally, he is the Degree Programme Director for MSc Drug Chemistry and the lead for radiochemistry within the Discovery of Medicines research theme in the Faculty of Medical Sciences. Interestingly, he also recently co-authored two textbooks on click chemistry and its role in radiochemistry!

The first author, Toni Pringle, is a PhD student who led the research in this paper!

Could you briefly explain the focus of your article to the non-specialist and why it is of current interest?
In the present era of precision medicine, antibodies have emerged as an important class of highly target-specific therapeutic drugs, particularly in oncology, yet their inefficient cellular internalisation limits their scope of application to disease targets situated on the exterior side of the cell membrane. This article is based on research led by PhD student Toni Pringle who modified Herceptin (an antibody used to treat HER2-positive breast and gastric cancers) with a peptide that confers cell-penetrating properties and examined how the extent of this modification affected the uptake of Herceptin in human breast cancer cells, resulting in data that advances our understanding of the cell-internalising properties of these constructs.

How big an impact could your results potentially have?
The results of our study shine a light on the significant influence of a fundamental molecular design parameter – the degree of cell-penetrating peptide labelling. Notably, we found that a radiolabelled analogue of Herceptin modified with five cell-penetrating peptides had uptake in HER2-expressing cells 14.7-fold higher after 48 hours compared to an equivalent analogue with no peptide modification. The scale of this enhancement is exciting when you consider its implications for enhancing the therapeutic index of antibody-drug conjugates, as well as its potential to expand the scope of antibody-based positron emission tomography imaging agents to include disease biomarkers located in the intracellular environment.

Could you explain the motivation behind this study?
The main focus of our research is the development of radiopharmaceuticals that can be used as imaging and/or therapeutic agents for cancer. We are particularly interested in radiopharmaceuticals based on antibody-cell penetrating peptide conjugates (Ab-CPPs) and our motivation in this case was to understand the extent to which cellular internalisation of cancer target-specific Ab-CPP is affected by the degree of peptide labelling. Our group is keen to expand in this area and we felt it was crucial to get a firm handle on this important parameter.

In your opinion, what are the key design considerations for your study?
To allow us to determine the degree of peptide labelling, we decided to use a bioconjugation strategy based on strain-promoted alkyne-azide cycloaddition as this provided a convenient way to measure this parameter by depletion of the alkyne absorbance in the UV region. We also had to think carefully about how to approach the cell-based assays which were fairly complex due to the need to consider several factors, such as the specific activity of the radiolabelled Ab-CPPs, cell numbers and how these would change over the course of the experiment (and how to account for this), the sensitivity of the gamma counter, and of course, radio-protection measures at each stage etc. I must say that Toni did a fabulous job here in the planning and implementation of these experiments.

Which part of the work towards this paper proved to be most challenging?
Working with radioisotopes can be challenging as the agents we put so much effort into making are continually and irretrievably disappearing from the moment we make them! As a result, we have to plan our work very carefully, and often this involves coordinating the activities of several people!

What aspect of your work are you most excited about at the moment?
Radiochemistry and imaging at Newcastle University is thriving and enjoying a period of expansion. The imminent opening of our radiopharmaceutical GMP suite will grant us the ability to readily translate our probes into the clinic, and we have a dedicated network of academics and clinicians supporting us in this endeavour. For me, this is an incredibly exciting prospect!

What is the next step? What work is planned?
We’re taking this forward in two ways. First, we are applying this approach to antibody-drug conjugates to examine the influence of DOL upon therapeutic efficacy in target cell populations. Second, we are developing PET radioligands based on Ab-CPPs to target intracellular biomarkers that arise early in the development of pancreatic cancer to facilitate early detection. In each case, we are applying new, improved cell penetrating peptides. We are looking forward to sharing the results of these investigations soon!

The influence of degree of labelling upon cellular internalisation of antibody-cell penetrating peptide conjugates.

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We are very pleased to introduce Professor Takashi Morii, who is the corresponding author of the RSC Advances article, A two-step screening to optimize the signal response of an auto-fluorescent protein-based biosensor. The manuscript was well received by reviewers and was handpicked by our reviewers and handling editors to be part of our Popular Advances collection.

Professor Mori told us more about the work that went into this article and what he hopes to achieve in the future. You can explore other articles in our 2022 Popular Advances online collection here.

Meet the author:

Takashi Morii was born in 1959 in Hyogo, Japan. He studied Chemistry at Kyoto University (B. Eng., 1982, Ph.D. 1988) with Prof. T. Matsuura and Prof. I. Saito. He conducted postdoctoral research with Prof. J. K. Barton at Columbia University and California Institute of Technology. In 1992, he was appointed as an Assistant Professor at Kyoto Institute of Technology and subsequently moved to Institute for Chemical Research at Kyoto University. In 1998, he moved to Institute of Advanced Energy, Kyoto University, where he was promoted to Professor in 2005.

Could you briefly explain the focus of your article to the non-specialist (in one or two sentences only) and why it is of current interest? 

Construction of an auto-fluorescent protein (AFP)-based biosensor consisting of a recognition, or a reaction, module and AFP often encounters difficulty owing to the lack of structural information for the recognition module and requirement of laborious tasks for functional optimization. This study describes a two-step screening strategy that allows facile optimization of the optical response of AFP-based biosensor for nitric oxide (NO), which is also applicable for many types of AFP-based biosensors.

How big an impact could your results potentially have? 

Our two-step, first in silico and second in vitro, screening strategy provides a convenient and high-throughput screening method for the optimization of the signal response of AFP-based biosensors. Especially, our strategy has an advantage for cases when the detailed information on the structural change of recognition module is not available. AFP-based biosensors are quite useful in visualizing the dynamics of cellular important factors because of their suitability for high spatiotemporal resolution and long-time imaging. Our strategy would accelerate the development of various types of biosensors for the factors of interest in the cell.

Could you explain the motivation behind this study?

We have previously constructed a fusion of a segment of the putative NO-sensing module of the TRPC5 channel with enhanced green fluorescent protein (EGFP) to evaluate this putative NO-induced structural change in TRPC5. While the construct successfully detected the putative structural change by the reaction with NO as a change in the fluorescence intensity ratio of EGFP, the observed response was quite weak. We considered that the TRPC5 loop-EGFP construct could be converted to a cellular NO sensor by enhancing its response through the mutation and screening. In addition, developing a general strategy to construct AFP-based biosensors that visualize various kinds of second messengers would promote further investigation of signal transduction.

In your opinion, what are the key design considerations for your study?  

An AFP-based biosensor is designed by conjugating an appropriate recognition or reaction module for a given target to an AFP transduction module. Structural changes in the recognition module induced by the recognition/reaction event are transduced to a change of fluorescence signal of AFP. To obtain usable AFP-based biosensors, many sensor candidates must be constructed and evaluated their responses, which are time consuming and required laborious tasks. We consider that a screening to select candidates showing larger structural changes at the reaction module upon the reaction based on in silico simulation in the first step would reduce these tasks. Structural change of the reaction modules of candidates are evaluated by root-mean-square-deviation (RMSD) of the coordinates for the backbone of reaction module between before and after the reaction based on in silico simulation.

Which part of the work towards this paper proved to be most challenging? 

The most challenging part of this work is whether the in silico screening evaluated by using the RMSD values could select candidates with reasonable signal responses because it is very difficult to predict the exact structural change of candidates upon the reaction in silico. Fortunately, the second in vitro screening revealed that RMSD values could successfully provide indexes for the signal response of the candidates, although large RMSD values did not always correspond to the large signal response.

What aspect of your work are you most excited about at the moment? 

It was quite exciting to find that the sensor candidates from the first in silico screening showed enhanced signals in the in vitro second screening. It was also exciting to confirm that a construct obtained from the two-step screening showed a reasonable signal response in living mammalian cells. This result demonstrated that our screening strategy can be applied to enhance the signal response sufficient for cellular applications.

What is the next step? What work is planned?

The reaction module of selected AFP-based biosensor changes its structure upon formation of a disulphide bond to emit the signal. We anticipated a certain selectivity for the disulphide bond formation by NO, but apparently the selected AFP-based biosensor showed similar response to NO and H₂O₂. The next step is to develop a convenient strategy to install a selectivity to NO and H₂O₂ on the AFP-based biosensor selected in this work.

A two-step screening to optimize the signal response of an auto-fluorescent protein-based biosensor

Shunsuke Tajima,^a Eiji Nakata,^a Reiko Sakaguchi,^b Masayuki Saimura,^a Yasuo Mori^c and Takashi Morii^*a

RSC Adv., 2022,12, 15407-15419

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