Modified Porphyrin Assemblies Show Potential as DNA Nanocarriers

A team of researchers recently published a paper in the journal ACS Langmuir that demonstrated the effectiveness of using porphyrin assemblies as nanocarriers for deoxyribonucleic acid (DNA).  

Modified Porphyrin Assemblies Show Potential as DNA Nanocarriers​​​​​​​

​​​​​​​Study: Adsorption of DNA Oligonucleotides by Self-Assembled Metalloporphyrin Nanomaterials. Image Credit: unoL/Shutterstock.com

Porphyrinsan Biosensors

DNA nanobiotechnology has been used extensively in recent years, with applications relating to drug delivery, biosensors, disease diagnosis, and biological imaging. Graphene oxide (GO) and metallic nanoparticles such as gold nanoparticles (AuNPs) are often used to detect small molecules or nucleic acids by physically absorbing aptamer and DNA probes in biosensors.

Two-dimensional (2D) materials and different metal oxides were studied extensively to investigate their applications in biosensors. However, macromolecular organic compounds such as porphyrins have not been studied on a similar scale for biosensing applications.

Porphyrins are widely used in applications related to photodynamic therapy as they possess robust light capture ability, rapid electron injection, excellent optical properties, and good biocompatibility. DNA and molecular porphyrins can form different binding structures.

Additionally, porphyrins possess a high molar extinction coefficient, which can be useful to develop biosensors as they can reduce the fluorescence of fluorophore-labeled DNA. However, porphyrins are typically insoluble in water and highly hydrophobic in nature. The solubility of porphyrin in water can be enhanced by preparing porphyrin assemblies.

Previous studies have demonstrated the effectiveness of iron porphyrin assemblies (FePNPs) in detecting the fluorescence of nucleic acid. However, more information is required about the influence of the porphyrin assembly morphology and aggregation structure in the detection and adsorption of nucleic acids.

The Study

In this study, researchers used zinc meso-tetra(4-pyridyl)porphyrin (ZnTPyP), a metalloporphyrin building block often used extensively in antibacterial, biophototherapy, and photocatalysis applications, to investigate the influence of zinc porphyrin assemblies with multiple aggregation structures on DNA adsorption.

ZnTPyP, DNA samples, 1 M hydrochloric acid (HCl), 1 M sodium hydroxide (NaOH), N-(2-hydroxyethyl)piperazine-N′-ethanesulfonic acid (HEPES), and emulsifiers that include sodium dodecyl sulfate (SDS), myristyl trimethyl ammonium bromide (MTAB), and cetyltrimethyl ammonium bromide (CTAB) were used as starting materials for the study. Milli-Q water with 18.2 M Ω resistivity was used to prepare all solutions in the study.

Transmission electron microscopy (TEM) with 200 kV acceleration voltage was performed using a JEOL IEM 2010, while an ultraviolet-visible (UV−vis) spectrophotometer was used to obtain the electronic absorption spectra. The crystalline structures of every porphyrin assembly were assessed using the X-ray diffraction (XRD) technique, while the zeta potential values were obtained using the dynamic light scattering (DLS) method.

0.5 mL ZnTPyP solution was quickly added into a 9.5 mL aqueous solution containing 0.01 M emulsifier and NaOH with rapid stirring, and then the resultant mixture was constantly stirred for 48 h at 25oC. In the final reaction system, the concentration of ZnTPyP was 0.5 mM.

The synthesized ZnTPyP assemblies were obtained at 15,000 rpm and subsequently washed two times with Milli-Q water to eliminate impurities and excess emulsifiers. The ZnTPyP assemblies with various morphologies were prepared using different types of emulsifiers, varying the ZnTPyP concentrations or adjusting the pH by NaOH.

Ten μL of carboxyfluorescein (FAM)-12-mer DNA was mixed with 90 μL of HEPES buffer containing ZnTPyP assemblies and incubated at room temperature for 10 min. Subsequently, the ZnTPyP assemblies were separated from the mixture by centrifugation at 15,000 rpm, and the fluorescence intensity of the assemblies containing the nanoabsorbed DNA was determined using a microplate reader. The reduced fluorescence in the assemblies was used to measure the DNA adsorption percentage.

The experiment was repeated with different DNA samples without changing the adsorption time and the concentration of porphyrin assemblies and DNA. The pH of the HEPES buffer was varied to determine the DNA adsorption in different pH values. Additionally, the adsorption of double- and single-stranded DNA were determined. DNA adsorption percentages of ZnTPyP assemblies were also measured after treating them with ethanol and urea.

Observations

Different aggregated ZnTPyP assemblies were synthesized and characterized successfully. Among the five ZnTPyP assemblies synthesized in this study, four assemblies were positively charged. A limited extent of DNA adsorption was observed in the negatively charged ZnNPs-6, indicating that other interaction forces were much stronger than the charge repulsion on the porphyrin assembly surface. The observation confirms that DNA adsorption can happen even when the charge of the DNA is the same as that of the assembly surface.

The porphyrin assemblies with a hexagonal stacking structure, specifically ZnNWs-6, exposed more functional groups that allowed hydrogen bonding and facilitated greater DNA adsorption. Hydrogen bonding was verified after the ZnTPyP assemblies were washed with urea.

No significant effect of the DNA length and sequence was observed on the adsorption percentages. The adsorption of single-stranded DNA was relatively more effective than the adsorption of double-stranded DNA, indicating the role played by the DNA bases in the adsorption process.

To summarize, the findings of this study provide a reference for the synthesis of novel porphyrin/DNA assembly composite materials and the surface interactions associated with them.  

Reference

Wang, J., Wang, Z., Liu, J. et al. (2022) Adsorption of DNA Oligonucleotides by Self-Assembled Metalloporphyrin Nanomaterials. ACS Langmuir. https://pubs.acs.org/doi/10.1021/acs.langmuir.2c00108

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Samudrapom Dam

Written by

Samudrapom Dam

Samudrapom Dam is a freelance scientific and business writer based in Kolkata, India. He has been writing articles related to business and scientific topics for more than one and a half years. He has extensive experience in writing about advanced technologies, information technology, machinery, metals and metal products, clean technologies, finance and banking, automotive, household products, and the aerospace industry. He is passionate about the latest developments in advanced technologies, the ways these developments can be implemented in a real-world situation, and how these developments can positively impact common people.

Citations

Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Dam, Samudrapom. (2022, March 15). Modified Porphyrin Assemblies Show Potential as DNA Nanocarriers. AZoNano. Retrieved on July 02, 2022 from https://www.azonano.com/news.aspx?newsID=38827.

  • MLA

    Dam, Samudrapom. "Modified Porphyrin Assemblies Show Potential as DNA Nanocarriers". AZoNano. 02 July 2022. <https://www.azonano.com/news.aspx?newsID=38827>.

  • Chicago

    Dam, Samudrapom. "Modified Porphyrin Assemblies Show Potential as DNA Nanocarriers". AZoNano. https://www.azonano.com/news.aspx?newsID=38827. (accessed July 02, 2022).

  • Harvard

    Dam, Samudrapom. 2022. Modified Porphyrin Assemblies Show Potential as DNA Nanocarriers. AZoNano, viewed 02 July 2022, https://www.azonano.com/news.aspx?newsID=38827.

Tell Us What You Think

Do you have a review, update or anything you would like to add to this news story?

Leave your feedback
Your comment type
Submit