GREEN SYNTHESIS OF GOLD NANOPARTICLES (AuNPs) USING Rhizophora apiculata BLUME AND Rhizophora mucronata LAM. AQUEOUS LEAF EXTRACTS: A PRELIMINARY EVALUATION
Ronnalyn P. Casupanan¹,2, Johnny A. Ching2,3, Christopher Jay T. Robidillo4
1Department of Arts and Sciences, St. Dominic College of Asia, Bacoor City, Cavite, Philippines
2College of Professional and Graduate Studies, De La Salle University–Dasmariñas, City of Dasmariñas, Cavite, Philippines
3College of Science, De La Salle University–Dasmariñas, City of Dasmariñas, Cavite, Philippines
4Department of Physical Sciences and Mathematics (DPSM), University of the Philippines, Manila
ABSTRACT
The increasing environmental concerns associated with conventional nanoparticle synthesis have accelerated interest in sustainable green nanotechnology. This study evaluated the feasibility of synthesizing gold nanoparticles (AuNPs) using aqueous leaf extracts of Rhizophora mucronata Lam. and Rhizophora apiculata Blume as biological reducing and stabilizing agents. Different extract-to-HAuCl4 volume ratios (45:1.25, 45:2.5, and 45:5) were prepared and incubated under continuous stirring at room temperature. Nanoparticle formation was monitored using UV–Vis spectrophotometry, while Fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used for characterization. Phytochemical screening confirmed the presence of alkaloids, flavonoids, tannins, and phenolic compounds in both extracts. FTIR spectra revealed hydroxyl, carbonyl, and C–O functional groups associated with nanoparticle reduction and stabilization. Stable surface plasmon resonance (SPR) peaks were observed at 547 nm for R. mucronata-mediated AuNPs and 543 nm for R. apiculata-mediated AuNPs. TEM analysis revealed spherical, triangular, and hexagonal nanoparticles with mean particle sizes of 56.7 ± 46.4 nm and 51.2 ± 40.2 nm, respectively. The acidic reaction conditions and prolonged reduction time likely contributed to anisotropic growth and particle polydispersity. The findings demonstrate that both mangrove species possess strong potential as eco-friendly biological resources for AuNP synthesis and provide baseline information for future optimization and biomedical applications.
Keywords: gold nanoparticles, green synthesis, mangroves, Rhizophora apiculata, Rhizophora mucronata, nanotechnology
Cite this Article:
Casupanan RP, Ching JA, & Robidillo CJT. 2026. Green Synthesis of Gold Nanoparticles (AuNPs) using Rhizophora apiculata Blume and Rhizophora mucronata lam. Aqueous Leaf Extracts: A Preliminary Evaluation. Lasaliksik. 3(2).
Polymer Composition and Environmental Characteristics of Microplastics in Manila–Bacoor Bay, Philippines
Eurika Innah Alyza O. Murano¹, Mark Angelo del Rosario², Michael C. Guyamin³
1College of Professional and Graduate Studies, De La Salle University–Dasmariñas, City of Dasmariñas, Cavite, Philippines
2College of Medicine, University of the Philippines, Manila
3College of Science, De La Salle University–Dasmariñas, City of Dasmariñas, Cavite, Philippines
ABSTRACT
Microplastic pollution is an emerging environmental concern in coastal systems because of its persistence, widespread distribution, and potential ecological and public health implications. This study characterized the physical features and polymer composition of microplastics collected from two coastal sites within the Manila–Bacoor Bay system, Philippines. The sites represented contrasting coastal conditions: a highly urbanized area in Barangay Pulvorista, Kawit, Cavite, and a comparatively less disturbed but livelihood-dependent coastal area in Barangay San Rafael IV, Noveleta, Cavite. Surface water samples were collected during the dry season and processed using stainless-steel sieves and laboratory sorting. Suspected microplastics were visually classified according to morphology and color, while representative particles were analyzed using Fourier transform infrared spectroscopy. Results showed that the recovered particles consisted mainly of fragments, fibers, and pellets, with colors including white, translucent, blue, red, orange, yellow, brown, purple, and mixed-color particles. Fourier transform infrared spectroscopy identified several polymers, including polyacrylamide, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, polyvinylpyrrolidone, cis-polyisoprene, polyacetylene, carboxymethyl cellulose, and cellulose-based materials. Site A showed polymers commonly associated with wastewater discharge, consumer packaging, road runoff, and urban activities, while Site B showed greater polymer diversity linked to fishing, aquaculture, domestic wastewater, textile materials, packaging, and shoreline livelihood activities. The findings indicate that microplastic contamination in Manila–Bacoor Bay is influenced by both land-based and marine-based sources. This study provides baseline evidence for polymer-level microplastic contamination in Bacoor Bay and highlights the need for integrated solid waste management, wastewater control, fisheries-sector waste recovery, and long-term coastal monitoring.
Keywords: microplastics, FTIR spectroscopy, polymer diversity, coastal pollution, Bacoor Bay, Manila Bay, plastic waste
Cite this Article:
Murano EIAO, del Rosario MA, & Guyamin MC. 2026. Polymer Composition and Environmental Characteristics of Microplastics in Manila–Bacoor Bay, Philippines. Lasaliksik. 3(2).
LASALIKSIK
Lasaliksik is a peer-reviewed journal published by the University Research Office of De La Salle University-Dasmariñas (DLSU-D) and serves as the University’s official publication for Science and Mathematics. The title of the journal highlights the Filipino word “saliksik” which translates to “to search/ research” and thus the journal’s goal of disseminating newly discovered knowledge as well as developments and extended results of scientific studies. More importantly, the journal aims to provide an academic platform for researchers to share their scholarly works and research endeavors in various disciplines of science and mathematics, both pure and applied.
Lasaliksik accepts original full articles, expository studies, research notes, review articles and perspectives for review and releases one volume per year having two issues.
Editorial Board
Editor-in-Chief
Dr. Johnny A. Ching (Biology, De La Salle University-Dasmariñas)
Associate Editor
Dr. Nelda A. Nacion (Mathematics, De La Salle University- Dasmariñas)
Managing Editor
Jaime Zeus Agustin (De La Salle University- Dasmariñas)
Members
Dr. Edwin A. Balila (Statistics, Adventist University of the Philippines)
Dr. Drexel H. Camacho (Chemistry, De La Salle University, Manila)
Dr. Julieta Z. Dungca (Microbiology, Centro Escolar University)
Dr. Ma. Melanie M. Guiang (Plant Science, Central Mindanao University)
Dr. Maria Carla F. Manzano (Physics, De La Salle University, Manila)
Dr. Veeranoot Nissapatorn (Microbio and Parasitology, Walailak University, Thailand)
Dr. Marie Christine M. Obusan (Environmental Science, University of the Phils., Diliman)
Dr. Hanna Arini Parhusip (Applied Mathematics, Universitas Kristen Satya Wacana Indonesia)
Dr. Maila de Lourdes Gomes Periera (Cell and Molecular Biology, University of Aviero, Portugal)
Dr. Janet M. Luistro (Ecotoxicology, De La Salle University- Dasmariñas)
Dr. Cristina C. Salibay (Biology, De La Salle University- Dasmariñas)
Dr. Ma. Theresa Christine C. Valdez (Mathematics, De La Salle University- Dasmariñas)
Dr. Elizabeth B. Villa (Crimonology, De La Salle University- Dasmariñas)