A fluorescent quantum dot conjugate to probe the interaction of Enterolobium contortisiliquum trypsin inhibitor with cancer cells

Natália R M Santos; Weslley F de Oliveira; Mariana P Cabrera; Clovis M Bezerra Filho; Leydianne L S Patriota; Thiago H Napoleão; Patrícia M G Paiva; Maria Luiza V Oliva; Paulo E Cabral Filho; Adriana Fontes; Maria T S Correia

doi:10.1016/j.ijbiomac.2023.126453

A fluorescent quantum dot conjugate to probe the interaction of Enterolobium contortisiliquum trypsin inhibitor with cancer cells

Int J Biol Macromol. 2023 Dec 1:252:126453. doi: 10.1016/j.ijbiomac.2023.126453. Epub 2023 Aug 22.

Affiliations

¹ Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil; Departamento de Biofísica e Radiobiologia, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil.
² Departamento de Química Fundamental, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Recife, PE, 50740-560, Brazil.
³ Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, 04044-020, Brazil; Núcleo de Pesquisas em Ciências Ambientais e Biotecnologia, Universidade Católica de Pernambuco, Recife, PE, 50050-900, Brazil.
⁴ Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil.
⁵ Departamento de Bioquímica, Universidade Federal de São Paulo, São Paulo, SP, 04044-020, Brazil.
⁶ Departamento de Biofísica e Radiobiologia, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil.
⁷ Departamento de Biofísica e Radiobiologia, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil. Electronic address: adriana.fontes@ufpe.br.
⁸ Departamento de Bioquímica, Centro de Biociências, Universidade Federal de Pernambuco, Recife, PE, 50670-901, Brazil. Electronic address: maria.tscorreia@ufpe.br.

PMID: 37619683
DOI: 10.1016/j.ijbiomac.2023.126453

Abstract

Serine proteases play crucial biological roles and have their activity controlled by inhibitors, such as the EcTI, a serine protease inhibitor purified from Enterolobium contortisiliquum seeds, which has anticancer activity. This study aimed to conjugate EcTI with quantum dots (QDs), fluorophores with outstanding optical properties, and investigate the interaction of QDs-EcTI nanoprobe with cancer cells. The conjugation was evaluated by fluorescence correlation spectroscopy (FCS) and fluorescence microplate assay (FMA). EcTI inhibitory activity after interaction with QDs was also analyzed. From FCS, the conjugate presented a hydrodynamic diameter about 4× greater than bare QDs, suggesting a successful conjugation. This was supported by FMA, which showed a relative fluorescence intensity of ca. 3815% for the nanosystem, concerning bare QDs or EcTI alone. The EcTI inhibitory activity remained intact after its interaction with QDs. From flow cytometry analyses, approximately 62% of MDA-MB-231 and 90% of HeLa cells were labeled with the QD-EcTI conjugate, suggesting that their membranes have different protease levels to which EcTI exhibits an affinity. Concluding, the QD-EcTI represents a valuable nanotool to study the interaction of this inhibitor with cancer cells using fluorescence-based techniques with the potential to unravel the intricate dynamics of interplays between proteases and inhibitors in cancer biology.

Keywords: Nanoparticle; Protease inhibitor; Tumor cells.

MeSH terms

Coloring Agents
Fabaceae* / chemistry
HeLa Cells
Humans
Neoplasms*
Quantum Dots*
Serine Proteases
Trypsin Inhibitors / pharmacology

Substances

Trypsin Inhibitors
Serine Proteases
Coloring Agents