NOVEL ANTIMICROBIAL NANO-FORMULATIONS USING PLANT-MEDIATED GREEN SYNTHESIS FROM HIBISCUS ROSA-SINENSIS L

Abstract

The present invention relates to a method for synthesizing silver nanoparticles (AgNPs) using an aqueous extract of Hibiscus rosa-sinensis L. leaves as a biogenic reducing and stabilizing agent. This eco-friendly, cost-effective green synthesis technique yields AgNPs with potent antimicrobial activity effective against various pathogenic bacterial and fungal strains. The method leverages the natural reducing and stabilizing capabilities of phytochemicals present in the Hibiscus extract, resulting in nanoparticles that exhibit significant potential for use in antimicrobial applications across fields including healthcare, medical devices, surface coatings, textiles, and pharmaceuticals. The invention also provides detailed methodologies for the composition, characterization, and assessment of the synthesized AgNPs, demonstrating their effectiveness in mitigating microbial infections.

Specification

Description:FIELD OF THE INVENTION
[001] The invention disclosed herein pertains to the fields of nanotechnology and microbiology, with specific emphasis on the green synthesis of silver nanoparticles (AgNPs) using plant-based extracts. This eco-friendly approach offers a sustainable alternative to conventional antimicrobial methods and promotes the use of plant-mediated synthesis for creating nanoparticles with enhanced antimicrobial efficacy, suitable for applications in healthcare, coatings, and pharmaceuticals.
BACKGROUND OF THE INVENTION
[002] The rise of antimicrobial resistance (AMR) presents a critical global health challenge, significantly undermining the efficacy of traditional antibiotics and posing serious risks to public health. Pathogens that were once easily treatable now demonstrate resistance to multiple antibiotics, leading to increased rates of infection, prolonged hospital stays, and higher mortality. This escalating threat has prompted urgent research into novel antimicrobial agents and alternative approaches to prevent and manage infections. Nanotechnology, particularly the use of nanoparticles with inherent antimicrobial properties, has emerged as a promising solution, offering new mechanisms to combat microbial resistance effectively.
[003] Silver nanoparticles (AgNPs) are among the most researched antimicrobial nanomaterials due to their broad-spectrum efficacy against bacteria, viruses, and fungi. Silver has been valued for centuries for its antimicrobial properties, yet it was only with the advent of nanotechnology that its full potential became apparent. At the nanoscale, silver exhibits unique physicochemical properties, allowing it to interact more effectively with microbial cells and disrupt essential cellular functions. However, the conventional chemical synthesis of silver nanoparticles often involves toxic reagents and environmentally harmful conditions, which has led to an increasing focus on green synthesis methods that utilize biological sources.
[004] "Green synthesis" refers to the production of nanoparticles using natural, renewable sources, such as plant extracts, microorganisms, or enzymes. This approach offers several advantages over chemical synthesis, including reduced toxicity, lower energy consumption, and minimized environmental impact. Plant-mediated green synthesis, in particular, has gained considerable attention due to its simplicity, scalability, and the potential for unique nanoparticle properties arising from the bioactive compounds in plant extracts. Plant extracts contain various phytochemicals, such as flavonoids, phenolic compounds, and tannins, which can serve as natural reducing and stabilizing agents, facilitating the synthesis of nanoparticles without the need for external additives.
[005] Hibiscus rosa-sinensis L., commonly known as the Chinese hibiscus, is a flowering plant widely recognized for its medicinal properties. Traditionally used in herbal medicine, Hibiscus leaves contain a rich profile of bioactive compounds with antioxidant and antimicrobial properties. These phytochemicals make Hibiscus an ideal candidate for green synthesis, as they not only enable the reduction of silver ions to form nanoparticles but also enhance the stability and functionality of the resulting particles. Leveraging Hibiscus extracts for nanoparticle synthesis thus presents a dual advantage: eco-friendly production and improved antimicrobial activity due to the combined effects of silver and plant-based bioactives.
[006] The invention of Hibiscus-mediated AgNP synthesis addresses a critical gap in the field of antimicrobial technology, combining the potency of silver nanoparticles with the sustainability of green synthesis. By offering a scalable, cost-effective, and environmentally responsible method for producing AgNPs, this invention is poised to provide versatile applications in healthcare, consumer products, and environmental management. It represents a significant step toward sustainable nanotechnology solutions that can reduce reliance on antibiotics and address the pressing issue of antimicrobial resistance.
OBJECTIVES OF THE INVENTION
[007] The primary objective of this invention is to provide a sustainable and cost-effective method for synthesizing silver nanoparticles (AgNPs) using an aqueous extract of Hibiscus rosa-sinensis L. leaves, leveraging the natural reducing and stabilizing properties of plant phytochemicals.
[008] Another objective of this invention is to demonstrate the enhanced antimicrobial efficacy of the plant-synthesized AgNPs against a broad spectrum of pathogenic bacterial and fungal strains.
[009] Yet another objective is to promote an eco-friendly alternative to conventional nanoparticle synthesis methods that often require toxic chemical agents, thereby minimizing environmental and health risks.
[010] Further another objective is to enable scalability of this green synthesis process, making it suitable for various industrial applications in fields such as healthcare, medical devices, coatings, textiles, and pharmaceuticals.
[011] Still another objective of the invention is to facilitate the integration of AgNPs into products that can prevent microbial contamination, with potential applications in antimicrobial coatings, fabrics, medical devices, and wound care formulations.
[012] Finally, an additional objective is to establish a standardized methodology for the synthesis, characterization, and assessment of these plant-mediated AgNPs, ensuring reliable quality and efficacy for end-user applications.
SUMMARY OF THE INVENTION
[013] The invention presents a novel method for the synthesis of silver nanoparticles (AgNPs) utilizing an aqueous extract of Hibiscus rosa-sinensis L. leaves as a biogenic reducing and stabilizing agent. The synthesized AgNPs exhibit significant antimicrobial efficacy against a wide range of bacterial and fungal strains. This process is designed to be environmentally benign, cost-effective, and scalable, rendering it suitable for diverse industrial applications. The antimicrobial potential of these AgNPs makes them particularly useful in creating antimicrobial coatings, medical devices, and other products that mitigate microbial contamination and infection. The invention further details the methods for the synthesis, composition, characterization, and assessment of the AgNPs, illustrating their effectiveness and utility for applications requiring antimicrobial properties.

DETAIL DESCRIPTION OF THE INVENTION

[014] This invention relates to the green synthesis of silver nanoparticles (AgNPs) utilizing an aqueous extract of Hibiscus rosa-sinensis L. leaves. Through this process, silver nanoparticles are formed by reducing silver ions (Ag?) using naturally derived reducing and capping agents from the Hibiscus leaf extract, resulting in stable, biologically active nanoparticles. The natural phytochemicals present in the leaves, including flavonoids, tannins, and phenolic compounds, facilitate this reduction process, eliminating the need for chemical reducing agents. This green synthesis approach yields nanoparticles with potent antimicrobial activity, making them suitable for various applications across healthcare, pharmaceuticals, textiles, and other industries.
[015] The invention's green synthesis method is particularly advantageous due to its environmental sustainability and cost efficiency. Traditional methods for synthesizing nanoparticles often rely on hazardous chemicals that can lead to environmental pollution and pose health risks. By contrast, the biogenic approach in this invention uses only plant extracts and distilled water in a controlled laboratory environment, thereby reducing toxicity and pollution while producing effective antimicrobial nanoparticles. This approach also aligns with current industrial goals of sustainability and minimizing ecological footprints.
[016] To begin the synthesis, fresh leaves of Hibiscus rosa-sinensis L. are collected, washed thoroughly to remove surface contaminants, and air-dried. After drying, the leaves are ground into a fine powder to maximize the surface area and increase extraction efficiency. The powdered leaves are then mixed with distilled water and heated at a controlled temperature between 60°C to 80°C. This heating process facilitates the release of bioactive compounds into the solution, producing a clear aqueous extract that is rich in phytochemicals capable of reducing silver ions.
[017] In this synthesis method, a silver nitrate (AgNO3) solution is prepared separately, which serves as the silver ion source. This solution is gradually introduced to the aqueous Hibiscus leaf extract under constant stirring to maintain uniform distribution. As the silver ions come into contact with the bioactive components in the extract, a reduction reaction occurs, resulting in the formation of silver nanoparticles. This reaction is typically indicated by a noticeable color change in the solution from pale yellow to deep brown, which is characteristic of silver nanoparticle formation.
[018] Controlling the temperature and pH of the reaction mixture is crucial for optimizing the size, shape, and stability of the nanoparticles. For instance, maintaining the pH at a slightly alkaline level favors the formation of smaller, more uniform nanoparticles, which are highly desirable for antimicrobial applications. Similarly, maintaining a constant temperature during the reaction enhances the efficiency of the reduction process and ensures consistent nanoparticle synthesis across batches.
[019] Once formed, the AgNPs are characterized using a range of analytical techniques to confirm their size, shape, crystallinity, and composition. Techniques such as UV-Vis spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM) are employed to evaluate the size and shape of the nanoparticles. The UV-Vis spectroscopy is particularly useful for tracking the surface plasmon resonance peak, which serves as an indicator of nanoparticle size and formation efficiency.
[020] Additional characterization techniques such as X-ray Diffraction (XRD) and Fourier-Transform Infrared Spectroscopy (FTIR) are used to assess the crystallinity and functional groups present on the nanoparticle surface. XRD analysis provides information on the crystalline structure of the nanoparticles, which is essential for determining their stability and reactivity. FTIR analysis, on the other hand, detects the functional groups from the plant extract that are bound to the surface of the AgNPs, serving as capping agents that stabilize the nanoparticles.
[021] The synthesized AgNPs exhibit potent antimicrobial activity, as demonstrated by standardized antimicrobial assays. To evaluate this activity, pathogenic bacterial and fungal strains are carefully selected, representing a range of clinically relevant microorganisms. The AgNPs' antimicrobial properties are assessed using methods such as the disk diffusion method, broth dilution, and minimum inhibitory concentration (MIC) determination. These assays allow for a detailed understanding of the nanoparticles' efficacy and potential clinical applications.
[022] The antimicrobial effectiveness of these AgNPs is primarily attributed to their small size and the presence of bioactive compounds from the Hibiscus extract, which may interact synergistically with the silver ions. The nanoparticles' small size allows for close contact with microbial cell membranes, disrupting their structural integrity and leading to cell death. The bioactive compounds in the plant extract are believed to enhance this interaction, resulting in heightened antimicrobial potency compared to conventionally synthesized AgNPs.
[023] The invention's AgNPs show considerable promise for use in medical devices, where their antimicrobial properties can prevent biofilm formation and reduce infection risks. By incorporating AgNPs into surface coatings for medical instruments, catheters, and implants, healthcare providers can significantly reduce the incidence of hospital-acquired infections. The nanoparticles can be integrated into a polymeric matrix to create stable, long-lasting antimicrobial coatings suitable for various medical applications.
[025] In addition to medical devices, these AgNPs can be applied to textiles, offering an effective solution for creating antimicrobial fabrics. Hospital linens, uniforms, and other textiles embedded with AgNPs provide ongoing protection against microbial contamination. The potential for AgNPs in the textile industry extends to consumer products as well, including antimicrobial clothing for athletic or outdoor activities where hygiene is a concern.
[026] Furthermore, this invention allows for the development of pharmaceutical formulations containing AgNPs for topical applications. Silver nanoparticles are well known for their wound-healing properties due to their ability to prevent microbial infections in open wounds. By incorporating AgNPs into creams, ointments, or sprays, this invention offers an effective solution for infection control in wound care, particularly in cases where patients are susceptible to antibiotic-resistant strains.
[027] The invention also presents significant potential for use in coatings for various environments, including public facilities, transportation, and food preparation surfaces. By integrating AgNPs into paints or other surface coatings, this invention enables the creation of antimicrobial surfaces that reduce microbial presence and provide continuous protection in high-traffic areas.
[028] An important aspect of this invention is the scalability of the synthesis process. Unlike traditional methods that require expensive chemicals and complex setups, this green synthesis approach can be easily scaled up using affordable, widely available plant materials and simple laboratory equipment. This scalability makes the invention highly suitable for industrial applications, particularly in developing regions where resources may be limited.
[029] The synergy between the antimicrobial properties of silver and the phytochemicals from Hibiscus is a unique feature of this invention. By combining these elements, the invention not only achieves effective antimicrobial activity but also reduces the amount of silver required, thereby minimizing potential toxicity concerns. The phytochemicals act as both reducing and capping agents, enhancing the nanoparticles' stability and biocompatibility, which is crucial for clinical and consumer applications.
[030] This invention provides an eco-friendly, cost-effective, and scalable method for synthesizing antimicrobial silver nanoparticles using Hibiscus leaf extract. The invention's AgNPs have demonstrated efficacy against a broad range of pathogens, including antibiotic-resistant strains, making them suitable for diverse applications in healthcare, textiles, coatings, and pharmaceuticals. The green synthesis method, coupled with the enhanced antimicrobial properties of the AgNPs, addresses critical challenges in infection control and microbial resistance, contributing to advancements in public health and safety.
[031] The AgNPs produced by this invention are characterized by their uniform size, shape, and stability, which are crucial for consistent antimicrobial performance. The thorough characterization of the nanoparticles ensures reproducibility and reliability, making this invention a valuable contribution to the field of nanotechnology and microbiology. Furthermore, the use of Hibiscus leaf extract as a reducing and stabilizing agent represents a significant advancement in sustainable nanomaterial synthesis, offering a viable alternative to traditional chemical methods.
[032] This invention, by focusing on green synthesis, also contributes to a broader shift toward sustainable technologies in the scientific and industrial communities. The methodology outlined here aligns with environmental and economic priorities, providing a model for future innovations in green nanotechnology. Through its various applications and benefits, this invention addresses pressing needs for safer, more effective antimicrobial solutions and serves as a pioneering example of plant-mediated nanomaterial synthesis.
[033] The process's environmental benefits also extend to the waste generated. Unlike chemical synthesis, which often requires neutralization and disposal of hazardous byproducts, this green synthesis method primarily produces harmless organic residues. The only significant byproduct in this method is the spent Hibiscus extract, which can be safely disposed of or even repurposed as a plant-based fertilizer. This aligns well with modern principles of green chemistry, where reducing and recycling waste is prioritized, making the invention suitable for integration into a circular economy framework.
[034] One of the essential factors influencing the stability of the silver nanoparticles in this invention is the unique chemical composition of the Hibiscus rosa-sinensis extract. The plant's extract contains natural antioxidants, which play a dual role in both reducing silver ions and stabilizing the formed nanoparticles. These antioxidants form a protective layer around each particle, preventing agglomeration and providing long-term stability. This unique natural capping mechanism ensures that the nanoparticles remain effective even over prolonged periods, which is a critical advantage for industrial and commercial applications.
[035] Another distinguishing feature of this invention is the reproducibility of the synthesis process. The conditions for the reaction, such as temperature, pH, and concentration ratios, are clearly defined and consistently replicable, making it possible to produce nanoparticles with uniform characteristics across different batches. This reproducibility is essential in applications where precise control over nanoparticle size and shape is critical, such as in medical or diagnostic tools, where any variation could affect efficacy.
[036] The invention's adaptability to various industrial applications is further demonstrated by the range of possible modifications. For example, by adjusting the concentration of the silver nitrate solution or the Hibiscus extract, it is possible to control the average size of the nanoparticles, which can be tailored to specific needs. Smaller particles, which have higher surface area-to-volume ratios, exhibit greater antimicrobial efficacy, whereas larger particles can be advantageous in applications that require prolonged, slow-release antimicrobial action. This versatility enhances the invention's appeal across industries.
[037] Furthermore, this method of synthesis, being both environmentally friendly and scalable, holds potential for significant economic impact. By offering an alternative to expensive and often toxic synthetic methods, this invention makes it possible to produce high-quality antimicrobial nanoparticles at a lower cost. This economic advantage can be particularly impactful in developing countries, where cost-effective antimicrobial solutions are essential to manage and prevent infections, especially in rural healthcare settings.
[038] The invention also provides a promising solution to a growing global health concern: antimicrobial resistance (AMR). AMR has limited the effectiveness of many conventional antibiotics, creating a demand for alternative approaches to infection control. The silver nanoparticles synthesized through this green method show potent antimicrobial effects against bacteria that are resistant to multiple drugs. Their unique mechanism of action, which disrupts bacterial cell walls and interferes with essential cellular functions, helps mitigate resistance issues and provides a viable substitute for traditional antibiotics.
[039] In addition to direct antimicrobial applications, the invention could find utility in water treatment and purification. The silver nanoparticles synthesized through this method could be incorporated into filtration materials to inhibit microbial growth in water systems. Their use in water filters or treatment facilities could help prevent the spread of waterborne pathogens, ensuring safe drinking water supplies and addressing a critical public health need, particularly in regions where access to clean water is limited.
[040] The bio-based synthesis approach used in this invention also aligns well with the principles of natural product chemistry, where researchers strive to harness the power of plant-derived compounds in innovative applications. By using Hibiscus leaf extract as the main reagent, this invention leverages the inherent biochemical diversity found in plants, paving the way for future explorations into other plant species that may yield unique antimicrobial nanoparticles. This opens the door for continued research into plant-based nanotechnology, fostering a deeper understanding of nature's resources.
[041] A critical aspect of this invention is its potential in consumer health products. Silver nanoparticles are increasingly found in products such as hand sanitizers, disinfectant sprays, and personal hygiene items. By using Hibiscus-based AgNPs, manufacturers can offer consumers a naturally derived alternative to chemically synthesized nanoparticles, appealing to health-conscious and environmentally aware customers. The demand for green and sustainable products is on the rise, making this invention well-timed to meet evolving market preferences.
[042] Finally, the invention's methodology could have implications for academic research and education. As the process involves safe, accessible materials and straightforward procedures, it could serve as an educational tool in fields such as chemistry, biology, and environmental science. By incorporating this green synthesis method into laboratory curricula, educators can teach students about sustainable practices in nanotechnology and microbiology. This educational impact could inspire future scientists and innovators to continue exploring eco-friendly solutions in technology. , Claims:I Claim:
1. An antimicrobial composition comprising silver nanoparticles synthesized by a method, wherein the method comprises:
preparing an aqueous extract of Hibiscus rosa-sinensis L. leaves;
mixing the aqueous extract with a silver nitrate solution under controlled temperature and pH conditions; and
allowing reduction of silver ions to form silver nanoparticles.
2. The method of claim 1, wherein the aqueous extract is prepared by heating Hibiscus rosa-sinensis L. leaves powder in distilled water at a temperature of 60°C to 80°C for 30 minutes.

3. The method of claim 1, wherein the silver nitrate solution concentration ranges from 0.5 mM to 2 mM.

4. The method of claim 1, wherein the resulting silver nanoparticles have a size range from 10 nm to 50 nm.

5. The antimicrobial composition of claim 1, further comprising the silver nanoparticles in a polymeric matrix for use in antimicrobial coatings.
6. The method of claim 1, wherein the silver nanoparticles are applied to a medical device to prevent microbial infection.

7. The method of claim 1, wherein the silver nanoparticles are used in a textile composition to produce antimicrobial fabrics.

8. The composition of claim 1, wherein the silver nanoparticles are incorporated into a pharmaceutical formulation for wound healing.

9. The composition of claim 1, wherein the silver nanoparticles are utilized in surface coatings to reduce microbial contamination.

10. The antimicrobial composition of claim 1, wherein the composition exhibits effective inhibition against both Gram-positive and Gram-negative bacteria.

Documents