Helium: Journal of Science and Applied Chemistry

Silver Nanoparticles in Point-of-Care Diagnostics: Enhancing Sensitivity, Selectivity, and Future Prospects

Martina Asti Rahayu — Mon, 01 Dec 2025 00:00:00 +0000

Silver nanoparticles (AgNPs) have emerged as indispensable nanomaterials for point-of-care (POC) medical diagnostics, due to their unique optical, electrical, and chemical properties that enhance sensor sensitivity, selectivity, and stability. This review systematically discusses the fundamental physicochemical characteristics of AgNPs, with emphasis on surface plasmon resonance (SPR) and its role in signal amplification in techniques such as surface-enhanced Raman spectroscopy (SERS), electrochemical biosensors, and immunosensors. Special attention is given to how synthesis strategies, including chemical, physical, and green, affect nanoparticle uniformity, biocompatibility, and functionalization potential. The review also compares surface modification approaches, including polymer coatings for stability, aptamer/antibody conjugation for specificity, and core–shell architectures for fluorescence enhancement, highlighting their impact on biomarker detection in complex biological matrices. By critically analyzing current challenges such as aggregation, oxidation, and nonspecific binding, the paper synthesizes recent advances in antifouling strategies, scalable production, and integration of AgNPs into portable and wearable diagnostic platforms. Unlike previous reviews, this work consolidates developments across synthesis, surface chemistry, and device engineering, and provides a forward-looking perspective on multiparametric and theragnostic applications. Overall, the paper underlines the importance of multidisciplinary collaboration to accelerate the translation of AgNPs-based sensors into clinically viable POC technologies for personalized healthcare and early disease detection.

Migration of Bisphenol A from Canned Sardines into Food Simulants: Effect of Temperature and Concentration

Alfin Ghanesa Putra, Sutanto Sutanto, Muhammad Fathurrahman — Mon, 01 Dec 2025 00:00:00 +0000

Epoxy resin coatings containing Bisphenol A (BPA) are widely used in canned food packaging, including sardine cans. They may pose a risk of chemical migration into food products under specific conditions. This study aimed to evaluate BPA migration into food simulants, acetic acid (1%, 3%, and 10%) and ethanol (10%, 20%, and 50%), at three temperatures (60 °C, 100 °C, and 121 °C). Migration levels were quantified using High-Performance Liquid Chromatography (HPLC) with UV-Vis detection. Preliminary analysis of five sardine can brands revealed BPA concentrations ranging from 0.0052 to 0.0487 mg/kg. Results demonstrated a significant increase in BPA migration with both simulant concentration and temperature. In ethanol, migration increased by 437% when the concentration rose from 10% to 50% at 121 °C, while a 92% increase was observed in acetic acid from 1% to 10% under the same conditions. Temperature had a more pronounced effect: BPA migration in 20% ethanol rose by 3,714% between 60 °C and 121 °C. Migration in 3% acetic acid increased from undetectable to 0.1515 mg/kg across the same temperature range. These findings indicate that BPA migration is significantly influenced by simulant type, concentration, and temperature, underscoring the necessity for stringent control over packaging conditions to ensure food safety.

Anti-cholesterol Activity of Kemuning Leaf Extract (Murraya paniculata (L.) Jack.) Using Different Extraction Methods and Solvents

Ardhalya Octarizha, Devy Susanty, Ade Ayu Oksari, Nurlela Nurlela — Mon, 01 Dec 2025 00:00:00 +0000

High cholesterol levels may accumulate in blood vessels, causing blockages. Reducing cholesterol levels using biological materials is an essential area of research currently to minimize the impact of chemical drugs. One of the biological materials with potential as an anti-cholesterol is the Kemuning plant (Murraya paniculata (L.) Jack). This study aims to determine the content of secondary metabolites, total phenolic content, total flavonoid content, and anti-cholesterol activity of Kemuning leaf extract, with variations in extraction methods and solvents. The extraction methods used were ultrasound-assisted extraction (UAE) and maceration. The solvents used in this study had different polarities, namely 96% ethanol, ethyl acetate, and n-hexane. The extract obtained from variations in extraction methods and solvents was tested for phytochemistry, total phenolics, total flavonoids, and in vitro anti-cholesterol activity using the Liebermann-Burchard method. The results showed that Kemuning leaf extract contained secondary metabolite compounds with anti-cholesterol activity. The best extraction method for secondary metabolites was the UAE method using 96% ethanol; however, the best EC50 value was obtained from maceration with ethyl acetate. The total phenolic content of the 96% ethanol extract of Kemuning leaf using the UAE method was 61.48 mg Gallic Acid Equivalent (GAE/g extract), the total flavonoid content was 100.77 mg Quercetin Equivalent (QE/g extract), and the anti-cholesterol activity had an EC₅₀ of 13.03 µg/mL.

Analysis of Lead (Pb) In Street Vendors' Urine at Antang Market, Makassar

Santi Santi, Lisda Maulina — Fri, 12 Dec 2025 00:00:00 +0000

Lead is a pollutant originating from motor vehicles. As a heavy metal, it is harmful to living organisms and may cause serious health problems. This study aimed to determine the levels of lead (Pb) in the urine of street vendors around the Antang market, Makassar. This study used an atomic absorption spectrophotometer (AAS) to analyze lead levels in the urine of 10 street vendors who met the study criteria. The results of this study showed that of 10 respondents, 4 had lead levels below the standard threshold, and 6 exceeded it. The highest level was 0.28 mg/L. This suggests that prolonged exposure is associated with higher urinary lead levels.

The Effect of pH on Adsorption Capacity Based on the Ionic Imprinted Polymer-Cd(II) Method

Nur Anisa Pungkasari, Maria Monica Sianita — Sat, 13 Dec 2025 00:00:00 +0000

Population growth and technological advancement in Indonesia have contributed to increasing environmental pollution, particularly from industrial waste containing heavy metals such as cadmium (Cd²⁺). This pollution poses serious health risks as cadmium can enter the food chain through aquatic ecosystems. Therefore, effective separation methods are required to remove cadmium from water bodies. One such method is the use of Ionic Imprinted Polymer (IIP), which offers high selectivity toward specific metal ions. This study aimed to determine the adsorption capacity of cadmium using the IIP method, synthesized via precipitation polymerization, over pH values ranging from 3 to 8. CdCl₂ was used as the ion template, combined with Na₂EDTA as a chelating ligand, methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and benzoyl peroxide (BPO) as the initiator. Characterization was conducted using Fourier Transform Infrared Spectroscopy (FTIR) to identify the functional groups and confirm template removal, and Scanning Electron Microscopy (SEM) to observe surface morphology. Adsorption performance was tested using Atomic Absorption Spectrophotometry (AAS). The IIP showed a specific absorption at 520 cm⁻¹ (Cd–O stretch), confirming the presence of cadmium-binding sites, and exhibited a porous morphology, unlike the dense structure of the blank polymer. The results showed that the optimum adsorption of Cd²⁺ occurred at pH 6, with an adsorption capacity of 4.47 mg/g, which was higher than that of the non-imprinted polymer (3.08 mg/g at pH 4). The improved adsorption performance at pH 6 is attributed to the predominance of the deprotonated EDTA form (Y⁴⁻), which forms a stable complex with Cd²⁺ (Kf ≈ 10¹⁶.⁵), thereby enhancing selective adsorption. These findings confirm that IIP-Cd is an effective material for cadmium removal from aqueous environments, with pH playing a critical role in optimizing adsorption capacity.

Synthesis of Activated Carbon from Coffee Bean Skin to Reduce BOD in Liquid Waste from Rambak Cracker Industry

Beby Putri Rahayu, Amaria — Sat, 13 Dec 2025 00:00:00 +0000

Liquid waste from the rambak cracker industry in Tulungagung primarily contains organic compounds that can lead to high levels of Biological Oxygen Demand (BOD). The objectives of this study were: 1) to determine the characteristics of activated carbon from coffee bean skins synthesized from coffee bean skins with different concentrations of H₃PO₄ activator. 2) to determine the effect of activated carbon mesh size on BOD levels of liquid waste from the Rambak Cracker Industry. Activated carbon from coffee bean skins was synthesized with H₃PO₄ as an activator at 5, 10, and 20% concentrations, with a 200-mesh size. The synthesis results were compared with liquid waste from the rambak cracker industry to determine the difference in BOD levels. The quality of activated carbon was analyzed in accordance with SNI 06-3730-1995, including water content, ash content, volatile matter content, bound carbon content, iodine absorption capacity, and functional groups. The results of the characterization of 200 mesh coffee bean skin activated carbon obtained water content of 5.00; 5.04; 5.18%, ash content of 3.37; 3.28; 2.62%, volatile matter content of 37.78; 36.67; 35.08%, bound carbon content of 53.85; 55.01; 57.12% and iodine absorption capacity of 998.51; 1011.21; 1023.9 mg/g. The results of functional group identification by FTIR showed that the functional groups detected in activated carbon were aliphatic CH, C=O, C-C, C=C, and C-O. BOD levels before and after contact with activated carbon were 2841.15 and 355.23 mg/L. The study concluded that 200-mesh coffee bean skin-activated carbon with a 20% H₃PO₄ activator can reduce BOD levels in liquid waste from the Rambak cracker industry by 87.5%.