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Sustained release and efficacy of Kn2-7-loaded chitosan nanoparticles under low pH conditions
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  • Published: 05 March 2026

Sustained release and efficacy of Kn2-7-loaded chitosan nanoparticles under low pH conditions

  • Bonke Phathekile  ORCID: orcid.org/0000-0002-2097-09581,2,
  • Nicole Remaliah Samantha Sibuyi  ORCID: orcid.org/0000-0001-7175-53882,3,
  • Samantha Meyer  ORCID: orcid.org/0000-0002-5167-06082,4,
  • Abram Madimabe Madiehe  ORCID: orcid.org/0000-0002-3935-467X2,5,
  • Grace Emily Okuthe  ORCID: orcid.org/0000-0001-6357-67426,
  • Martin Opiyo Onani  ORCID: orcid.org/0000-0002-4735-36691 &
  • …
  • Mervin Meyer  ORCID: orcid.org/0000-0002-8296-48602 

Scientific Reports , Article number:  (2026) Cite this article

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We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Subjects

  • Biotechnology
  • Chemistry
  • Drug discovery
  • Microbiology
  • Nanoscience and technology

Abstract

Delivery of antimicrobial peptides to low-pH sites is a significant challenge, and results in reduced treatment efficacy for vaginal infections. Chitosan nanoparticles (CNPs) could be ideal vehicles for drugs to acidic pH environments and sustain their therapeutic effects. CNPs were synthesized using the ionic gelation technique and loaded with Kn2-7 peptide. The CNPs were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, high-resolution transmission and scanning electron microscopes. The stability and antibacterial effects of Kn2-7-loaded CNPs were evaluated at low and normal pH levels. The CNPs had a size distribution of 327–416 nm and a zeta potential of 9.61–23.9 mV. The size distribution (340.2–753.7 nm) and Zeta potential (15.9–67.7 mV) of CNPs changed after loading Kn2-7. The CNPs loading capacity and Kn2-7 entrapment efficiency were 35.6% and 78.3%, respectively. The Kn2-7-CNPs were not stable at low-pH and released Kn2-7 instantly; however, stabilization of Kn2-7-CNPs with poly (acrylic acid) (PAA) and tripolyphosphate (TPP) increased their stability and sustained Kn2-7 release at acidic pH. The Kn2-7-CNPs_1 mg/mL TPP-PAA inhibited the growth of Staphylococcus aureus at pH 3.8 better than the Kn2-7 alone. Therefore, the Kn2-7-CNPs_1mg/mL TPP-PAA could serve as a promising candidate for protecting and delivering drugs in low-pH environments.

Data availability

The data presented in this manuscript can be requested from the corresponding authors on reasonable request.

References

  1. Rosenstein, I. J. et al. Effect on normal vaginal flora of three intravaginal microbicidal agents potentially active against human immunodeficiency virus type 1. J. Infect. Dis. 177, 1386–1390. https://doi.org/10.1086/517820 (1998).

    Google Scholar 

  2. Sánchez-Sánchez, M. P. et al. Chitosan and Kappa-Carrageenan vaginal acyclovir formulations for prevention of genital Herpes. In vitro and ex vivo evaluation. Mar. Drugs. 13, 5976–5992. https://doi.org/10.3390/md13095976 (2015).

    Google Scholar 

  3. Lund, P., Tramonti, A. & De Biase, D. Coping with low pH: molecular strategies in neutralophilic bacteria. FEMS Microbiol. Rev. 38, 1091–1125. https://doi.org/10.1111/1574-6976.12076 (2014).

    Google Scholar 

  4. Nakano, F. Y., Leão, R. & de BF, Esteves, S. C. Insights into the role of cervical mucus and vaginal pH in unexplained infertility. Med. Express. 2, 1–8. https://doi.org/10.5935/MedicalExpress.2015.02.07 (2015).

    Google Scholar 

  5. Hmed, B., Serria, H. T. & Mounir, Z. K. Scorpion peptides: potential use for new drug development. J. Toxicol. 2013, 1–15. https://doi.org/10.1155/2013/958797 (2013).

    Google Scholar 

  6. Notario-Pérez, F., Ruiz-Caro, R. & Veiga-Ochoa, M. D. Historical development of vaginal microbicides to prevent sexual transmission of HIV in women: from past failures to future hopes. Drug Des. Devel Ther. 11, 1767–1787. https://doi.org/10.2147/DDDT.S133170 (2017).

    Google Scholar 

  7. Cutler, B. & Justman, J. Vaginal microbicides and the prevention of HIV transmission. Lancet Infect. Dis. 8, 685–697. https://doi.org/10.1016/S1473-3099(08)70254-8 (2008).

    Google Scholar 

  8. Choudhury, A., Das, S. & Kar, M. A review on novelty and potentiality of vaginal drug delivery. Int. J. PharmTech Res. 3, 1033–1044 (2011).

    Google Scholar 

  9. Lei, J. et al. The antimicrobial peptides and their potential clinical applications. Am. J. Transl. Res.11: 3919–3931. (2019).

  10. Fadaka, A. O., Sibuyi, N. R. S., Madiehe, A. M. & Meyer, M. Nanotechnology-based delivery systems for antimicrobial peptides. Pharmaceutics 13 https://doi.org/10.3390/pharmaceutics13111795 (2021).

  11. Chen, Y. et al. Anti-HIV-1 activity of a new Scorpion venom peptide derivative Kn2-7. ;7: 1–9. (2012). https://doi.org/10.1371/journal.pone.0034947

  12. Inthanachai, T. et al. The inhibitory effect of human Beta-defensin-3 on Candida glabrata isolated from patients with candidiasis. Immunol. Invest. 50, 80–91. https://doi.org/10.1080/08820139.2020.1755307 (2021).

    Google Scholar 

  13. Pauwels, R. & De Clercq, E. Development of vaginal microbicides for the prevention of heterosexual transmission of HIV. J. Acquir. Immune Defic. Syndr. Hum. Retrovirology. 11, 211–221. https://doi.org/10.1097/00042560-199603010-00001 (1996).

    Google Scholar 

  14. Kumari, P., Ghosh, B. & Biswas, S. Nanocarriers for cancer-targeted drug delivery. J. Drug Target. 24, 179–191. https://doi.org/10.3109/1061186X.2015.1051049 (2016).

    Google Scholar 

  15. Debi Prasanna, M., Yogesh, P., Palve, D. & Sahoo, Nayak, P. L. Synthesis and characterization of Chitosan/Cloisite 30B (MMT) nanocomposite for controlled release of anticancer drug Curcumin. Int. J. Pharm. Res. Allied Sci. 1, 52–62 (2012).

    Google Scholar 

  16. Robertson, J. 11119. Am Math Mon. 111: 915. (2004). https://doi.org/10.2307/4145104

  17. Qi, L., Xu, Z., Jiang, X., Hu, C. & Zou, X. Preparation and antibacterial activity of Chitosan nanoparticles. ;339: 2693–2700. (2004). https://doi.org/10.1016/j.carres.2004.09.007

  18. Kean, T. & Thanou, M. Biodegradation, biodistribution and toxicity of Chitosan ☆. Adv. Drug Deliv Rev. 62, 3–11. https://doi.org/10.1016/j.addr.2009.09.004 (2010).

    Google Scholar 

  19. Filippov, S. K. et al. Dynamic light scattering and transmission electron microscopy in drug delivery: a roadmap for correct characterization of nanoparticles and interpretation of results. Mater. Horizons. 10, 5354–5370. https://doi.org/10.1039/d3mh00717k (2023).

    Google Scholar 

  20. Bodnar, M., Hartmann, J. F. & Borbely, J. Preparation and characterization of chitosan-based nanoparticles. Biomacromolecules 6, 2521–2527. https://doi.org/10.1021/bm0502258 (2005).

    Google Scholar 

  21. Honary, S. & Zahir, F. Effect of zeta potential on the properties of Nano-Drug delivery Systems - A review (Part 1). Trop. J. Pharm. Res. 12, 255–264 (2013).

    Google Scholar 

  22. Banerjee, T., Mitra, S., Kumar Singh, A., Kumar Sharma, R. & Maitra, A. Preparation, characterization and biodistribution of ultrafine Chitosan nanoparticles. Int. J. Pharm. 243, 93–105. https://doi.org/10.1016/S0378-5173(02)00267-3 (2002).

    Google Scholar 

  23. Eskandari, N. M. D., Zolfagharian, R. & Mohammad, H. Preparation and in vitro characterization of Chitosan nanoparticles containing mesobuthus Eupeus Scorpion venom as an antigen delivery system. J. Venom. Anim. Toxins Incl. Trop. Dis. 18, 44–52. https://doi.org/10.1590/S1678-91992012000100006 (2012).

    Google Scholar 

  24. Gimondi, S., Ferreira, H., Reis, R. L. & Neves, N. M. Intracellular trafficking of Size-Tuned nanoparticles for drug delivery. Int. J. Mol. Sci. 25 https://doi.org/10.3390/ijms25010312 (2024).

  25. Vedantam, P., Huang, G. & Tzeng, T. R. J. Size-dependent cellular toxicity and uptake of commercial colloidal gold nanoparticles in DU-145 cells. Cancer Nanotechnol. 4, 13–20. https://doi.org/10.1007/s12645-013-0033-8 (2013).

    Google Scholar 

  26. Hoshyar, N., Gray, S., Han, H. & Bao, G. The effect of nanoparticle size on in vivo pharmacokinetics and cellular interaction. Nanomedicine 11, 673–692. https://doi.org/10.2217/nnm.16.5 (2016).

    Google Scholar 

  27. Wang, Z. L. New developments in transmission electron microscopy for nanotechnology. Adv. Mater. 15, 1497–1514. https://doi.org/10.1002/adma.200300384 (2003).

    Google Scholar 

  28. Kiilll, C. P. et al. Synthesis and factorial design applied to a novel chitosan/sodium polyphosphate nanoparticles via ionotropic gelation as an RGD delivery system. Carbohydr. Polym. 157, 1695–1702. https://doi.org/10.1016/j.carbpol.2016.11.053 (2017).

    Google Scholar 

  29. Hasheminejad, N., Khodaiyan, F. & Safari, M. Improving the antifungal activity of clove essential oil encapsulated by Chitosan nanoparticles. Food Chem. 275, 113–122. https://doi.org/10.1016/j.foodchem.2018.09.085 (2019).

    Google Scholar 

  30. Amidi, M. et al. Preparation and characterization of protein-loaded N-trimethyl Chitosan nanoparticles as nasal delivery system. J. Control Release. 111, 107–116. https://doi.org/10.1016/j.jconrel.2005.11.014 (2006).

    Google Scholar 

  31. Khan, S. & Anwar, N. Highly porous pH-Responsive carboxymethyl Chitosan- grafted -Poly (Acrylic Acid) based smart hydrogels for 5-Fluorouracil controlled delivery and colon targeting. Int. J. Polym. Sci. 2019, 1–15. https://doi.org/10.1155/2019/6579239 (2019).

    Google Scholar 

  32. Elfadil, D., Elkhatib, W. F., El-sayyad, G. S. & Nps, A. Microbial pathogenesis promising advances in nanobiotic-based formulations for drug specific targeting against multidrug-resistant microbes and biofilm-associated infections. Microb. Pathog. 170, 105721. https://doi.org/10.1016/j.micpath.2022.105721 (2022).

    Google Scholar 

  33. Chakraborty, N., Jha, D., Roy, I., Kumar, P. & Gaurav, S. S. Nanobiotics against antimicrobial resistance: Harnessing the power of nanoscale materials and technologies. J. Nanobiotechnol. 20, 375. https://doi.org/10.1186/s12951-022-01573-9 (2022).

  34. Grenha, A., Seijo, B. & Remuñán-López, C. Microencapsulated Chitosan nanoparticles for lung protein delivery. Eur. J. Pharm. Sci. 25, 427–437. https://doi.org/10.1016/j.ejps.2005.04.009 (2005).

    Google Scholar 

  35. Kavaz, D., Kirac, F., Kirac, M. & Vaseashta, A. Low releasing mitomycin C molecule encapsulated with Chitosan nanoparticles for intravesical installation. J. Biomater. Nanobiotechnol. 08, 203–219. https://doi.org/10.4236/jbnb.2017.84014 (2017).

    Google Scholar 

  36. Bhardwaj, P. & Singh, S. Formulation and in vitro evaluation of pH-sensitive Chitosan beads of flurbiprofen. Indian Journal of Drugs. 1, 48–54. (2013).

  37. Fathi, M. et al. Stimuli-responsive chitosan-based nanocarriers for cancer therapy. Bioimpacts. 7, 269–277. (2017). https://doi.org/10.15171/bi.2014.008

  38. Hui Zhang, J. W. Review on bioactive peptides and Pharmacological activities of Buthus martensii Karsch. Biochem. Pharmacol. 4 (2). https://doi.org/10.4172/2167-0501.1000166 (2015).

  39. Cao, L. et al. Antibacterial activity and mechanism of a Scorpion venom peptide derivative in vitro and in vivo. PLoS One. 7, (2012). https://doi.org/10.1371/journal.pone.0040135

  40. Malcolm, R. K., Woolfson, A. D., Toner, C. F., Morrow, R. J. & Mccullagh, S. D. Long-term, controlled release of the HIV microbicide TMC120 from silicone elastomer vaginal rings. J. Antimicrob. Chemother. 56, 954–956. (2005). https://doi.org/10.1093/jac/dki326

  41. Tuğcu-Demiröz, F. et al. Development and characterization of Chitosan nanoparticles loaded nanofiber hybrid system for vaginal controlled release of benzydamine. Eur. J. Pharm. Sci. 161, 105801. https://doi.org/10.1016/j.ejps.2021.105801 (2021).

  42. Zambito, Y. Nanoparticles based on Chitosan derivatives. Advances in Biomaterials Science and Biomedical Applications, Ed Pignatello R, pp 243–263. https://doi.org/10.5772/54944 (2013).

  43. Liu, M. et al. Efficient mucus permeation and tight junction opening by dissociable mucus-inert agent coated trimethyl Chitosan nanoparticles for oral insulin delivery. J. Control Release. 222, 67–77. https://doi.org/10.1016/j.jconrel.2015.12.008 (2016).

    Google Scholar 

  44. Sahasathian, T. et al. Sustained release of amoxicillin from Chitosan tablets. Arch. Pharm. Res. 30, 526–531. https://doi.org/10.1007/BF02980229 (2007).

    Google Scholar 

  45. Hussein-al-ali, S. H., Kura, A., Hussein, M. Z. & Fakurazi, S. Preparation of Chitosan nanoparticles as a drug delivery system for Perindopril erbumine. Polym. Compos. 59, 544-552. https://doi.org/10.1002/pc.23967 (2016).

  46. Wu, Y. et al. Facile fabrication of poly(acrylic acid) coated Chitosan nanoparticles with improved stability in biological environments. Eur. J. Pharm. Biopharm. 112, 148–154. https://doi.org/10.1016/j.ejpb.2016.11.020 (2017).

    Google Scholar 

  47. Saeed, R. M., Dmour, I. & Taha, M. O. Stable Chitosan-Based nanoparticles using polyphosphoric acid or hexametaphosphate for tandem Ionotropic/Covalent crosslinking and subsequent investigation as novel vehicles for drug delivery. Front. Bioeng. Biotechnol. 8, 4. https://doi.org/10.3389/FBIOE.2020.00004/BIBTEX (2020).

    Google Scholar 

  48. Id, Z. D. et al. Application of BisANS fluorescent dye for developing a novel protein assay. PLoS One. 14, e0215863. https://doi.org/10.1371/journal.pone.0215863 (2019).

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Acknowledgements

The research data presented herein is part of Dr Bonke Phathekile’s MSc project “Synthesis of peptide-loaded chitosan nanoparticles for the treatment of sexually transmitted infections (STI’s), 2020” that is available on the university website.

Funding

This research was funded by NRF-Thuthuka Rating Track, Grant number TTK150625121238; UID: 99307 and UWC Natechnology platform.

Author information

Authors and Affiliations

  1. Organometallics and Nanomaterials, Department of Chemical Sciences, University of the Western Cape, Bellville, South Africa

    Bonke Phathekile & Martin Opiyo Onani

  2. DSTI/TIA Nanotechnology Platform, Department of Biotechnology, University of the Western Cape, Bellville, South Africa

    Bonke Phathekile, Nicole Remaliah Samantha Sibuyi, Samantha Meyer, Abram Madimabe Madiehe & Mervin Meyer

  3. Health Platform, Advanced Materials Division, Mintek, Randburg, Gauteng, South Africa

    Nicole Remaliah Samantha Sibuyi

  4. Phytotherapy Research Group, Department of Biomedical Sciences, Faculty of Health and Wellness Sciences, Cape Peninsula University of Technology, Cape Town, South Africa

    Samantha Meyer

  5. Nanobiotechnology Research Group, Department of Biotechnology, University of the Western Cape, Bellville, South Africa

    Abram Madimabe Madiehe

  6. Department of Biological and Environmental Sciences, Walter Sisulu University, Mthatha, South Africa

    Grace Emily Okuthe

Authors
  1. Bonke Phathekile
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  2. Nicole Remaliah Samantha Sibuyi
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Contributions

SM, AMM, GEO, MOO and MM - Conceptualization, resources, supervision, funding acquisition; BP and NRSS - methodology, project administration, formal analysis, investigation and data curation; BP – writing-original draft preparation; NRSS, SM, AMM, GEO, MOO and MM – writing-review and editing. All authors have read and agreed to the published version of the manuscript.

Corresponding authors

Correspondence to Nicole Remaliah Samantha Sibuyi, Martin Opiyo Onani or Mervin Meyer.

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Phathekile, B., Sibuyi, N.R.S., Meyer, S. et al. Sustained release and efficacy of Kn2-7-loaded chitosan nanoparticles under low pH conditions. Sci Rep (2026). https://doi.org/10.1038/s41598-026-37673-x

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  • Received: 08 March 2025

  • Accepted: 23 January 2026

  • Published: 05 March 2026

  • DOI: https://doi.org/10.1038/s41598-026-37673-x

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Keywords

  • Antimicrobial peptides
  • Chitosan nanoparticles
  • Kn2-7 peptide
  • Microbicides
  • Sexually transmitted infections
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