Potential use of gold-silver core-shell nanoparticles derived from Garcinia mangostana peel for anticancer compound, protocatechuic acid delivery

Colorectal cancer is one of the most killing cancers and this has become a global problem. Current treatment and anticancer drugs cannot specifically target the cancerous cells, thus causing toxicity towards surrounding non-cancer cells. Hence, there is an urgent need to discover a more target-specific therapeutic agent to overcome this problem. Core-shell nanoparticles have emerged as good candidate for anticancer treatment. This study aimed to synthesize core-shell nanoparticles via green method which utilised crude peels extract of Garcinia mangostana as reducing and stabilising agents for drug delivery. Gold-silver core-shell nanoparticles (Au-AgNPs) were synthesized through seed germination process in which gold nanoparticles acted as the seed. A complete coating was observed through transmission electron microscopy (TEM) when the ratio of AuNPs and AgNPs was 1:9. The size of Au-AgNPs was 38.22 ± 8.41 nm and was mostly spherical in shape. Plant-based drug, protocatechuic acid (PCA) was loaded on the Au-AgNPs to investigate their anticancer activity. In HCT116 colon cancer cells, PCA-loaded Au-AgNPs (IC₅₀ = 10.78 μg/ml) showed higher inhibitory action than the free PCA (IC₅₀= 148.09 μg/ml) and Au-AgNPs alone (IC₅₀= 24.36 μg/ml). Up to 80% inhibition of HCT116 cells was observed after the treatment of PCA-loaded Au-AgNPs at 15.63 μg/ml. The PCA-loaded Au-AgNPs also showed a better selectivity towards HCT116 compared to CCD112 colon normal cells when tested at the same concentrations. These findings suggest that Au-AgNPs system can be used as a potent nanocarrier to combat cancerous cells by offering additional anticancer properties to the loaded drug.

Silver nanomaterials: synthesis and (electro/photo) catalytic applications

In view of their unique characteristics and properties, silver nanomaterials (Ag NMs) have been used not only in the field of nanomedicine but also for diverse advanced catalytic technologies. In this comprehensive review, light is shed on general synthetic approaches encompassing chemical reduction, sonochemical, microwave, and thermal treatment among the preparative methods for the syntheses of Ag-based NMs and their catalytic applications. Additionally, some of the latest innovative approaches such as continuous flow integrated with MW and other benign approaches have been emphasized that ultimately pave the way for sustainability. Moreover, the potential applications of emerging Ag NMs, including sub nanomaterials and single atoms, in the field of liquid-phase catalysis, photocatalysis, and electrocatalysis as well as a positive role of Ag NMs in catalytic reactions are meticulously summarized. The scientific interest in the synthesis and applications of Ag NMs lies in the integrated benefits of their catalytic activity, selectivity, stability, and recovery. Therefore, the rise and journey of Ag NM-based catalysts will inspire a new generation of chemists to tailor and design robust catalysts that can effectively tackle major environmental challenges and help to replace noble metals in advanced catalytic applications. This overview concludes by providing future perspectives on the research into Ag NMs in the arena of electrocatalysis and photocatalysis.

Application of Polypodiopsida Class in Nanotechnology-Potential towards Development of More Effective Bioactive Solutions

The area of phytosynthesized nanomaterials is rapidly developing, with numerous studies being published yearly. The use of plant extracts is an alternative method to reduce the toxic potential of the nanomaterials and the interest in obtaining phytosynthesized nanoparticles is usually directed towards accessible and common plant species, ferns not being explored to their real potential in this field. The developed nanoparticles could benefit from their superior antimicrobial and antioxidant properties (compared with the nanoparticles obtained by other routes), thus proposing an important alternative against health care-associated and drug-resistant infections, as well as in other types of applications. The present review aims to summarize the explored application of ferns in nanotechnology and related areas, as well as the current bottlenecks and future perspectives, as emerging from the literature data.

Recent Progress in the Synthesis of Quinolines

BACKGROUND

Quinoline-containing compounds present in both natural and synthetic products are an important class of heterocyclic compounds. Many of the substituted quinolines have been used in various areas including medicine as drugs. Compounds with quinoline skeleton possess a wide range of bioactivities such as antimalarial, anti-bacterial, anthelmintic, anticonvulsant, antiviral, anti-inflammatory, and analgesic activity. Due to such a wide range of applicability, the synthesis of quinoline derivatives has attracted a lot of attention of chemists to develop effective methods. Many known methods have been expanded and improved. Furthermore, various new methods for quinoline synthesis have been established. This review will focus on considerable studies on the synthesis of quinolines date which back to 2014.

OBJECTIVE

In this review, we discussed recent achievements on the synthesis of quinoline compounds. Some classical methods have been modified and improved, while other new methods have been developed. A vast variety of catalysts were used for these transformations. In some studies, quinoline synthesis reaction mechanisms were also displayed.

CONCLUSION

Many methods for the synthesis of substituted quinoline rings have been developed recently. Over the past five years, the majority of those reported have been based on cycloisomerization and cyclization processes. Undoubtedly, more imaginative approaches to quinoline synthesis will appear in the literature in the near future. The application of known methods to natural product synthesis is probably the next challenge in the field.

MOF-5 as a highly efficient and recyclable catalyst for one pot synthesis of 2,4-disubstituted quinoline derivatives

An approach was developed for the synthesis of 2,4-disubstituted quinoline derivatives via a one pot three-component reaction of aromatic amines, aldehydes and alkynes catalyzed by MOF-5 under solvent-free conditions.

Tailored Engineering of Bimetallic Plasmonic Au@Ag Core@Shell Nanoparticles

A distinctive synthetic method for the efficient synthesis of multifunctional bimetallic plasmonic Au@Ag core@shell nanoparticles (NPs) with tunable size, morphology, and localized surface plasmon resonance (LSPR) using Triton X-100/hexanol-1/deionized water/cyclohexane-based water-in-oil (W/O) microemulsion (ME) is described. The W/O ME acted as a "true nanoreactor" for the synthesis of Au@Ag core@shell NPs by providing a confined and controlled environment and suppressing the nucleation, growth, agglomeration, and aggregation of the NPs. High-resolution transmission electron microscopic analysis of the synthesized Au@Ag core@shell NPs revealed an "unusual core@shell" contrast, and the selected area electron diffraction and Moiré patterns showed that Au layers are paralleled to Ag layers, thus indicating the formation of Au@Ag core@shell NPs. Interestingly, the UV-visible spectrum of the Au@Ag core@shell NPs exhibited enthralling plasmonic properties by introducing a high-frequency quadrupolar LSPR mode originated from the isolated Au@Ag NPs along with a low-frequency dipolar LSPR mode originated from the coupled Au@Ag NPs. The effective plasmonic enhancement of the Au@Ag core@shell NPs is attributed to the extreme enhancement of the localized electromagnetic field by coupling of the localized surface plasmons of the Au core and Ag shell. The mechanisms for the nucleation and growth of Au@Ag core@shell NPs in W/O ME have been proposed. A unique electron transfer phenomenon between the Au core and Ag shell is elucidated for better understanding and manipulation of the electronic properties, which evinced the development of Au@Ag core@shell NPs through suppression of the galvanic replacement reaction.

Environmentally sustainable route to SiO2@Au-Ag nanocomposites for biomedical and catalytic applications

A facile, sustainable, operationally simple and mild method for the synthesis of SiO2@Au-Ag nanocomposites (NCs) using Nephrolepis cordifolia tuber extract is described and its catalytic, antibacterial and cytotoxic properties were investigated. The fabricated SiO2@Au-Ag NCs were well characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) to determine the optical activity, size and morphology, elemental composition, functional groups present, crystallinity, thermal stability and chemical state respectively. The obtained SiO2@Au-Ag NCs exhibited spherical shape SiO2 decorated with Au and Ag nanoparticles. The diameter of the SiO2 nanoparticles ranges from 200-246 with average 3 nm diameter of Au and Ag NPs. Synthetic utility of this protocol has been demonstrated by exploring its effective catalytic activities for the solvent-free amidation of carboxylic acid with a primary amine with excellent yields. Moreover, the synthesized nanocomposite exhibited as noticeable antibacterial effect against Gram negative and Gram positive bacteria and better bio-compatibility against human keratinocytes. Thus, additive free SiO2@Au-Ag NCs display the potential for catalysis and biomedical applications.