Nanotechnology is an advancing field of science and technology that focuses on metals and metal oxides at the nanoscale. It can be described as the synthesis and design of nanoscale structures, specifically nanoparticles, which have sizes ranging from 1 to 100 nanometers [1, 2]. These nanoparticles are produced using a variety of methods, predominantly categorized as chemical, physical, and biological approaches. Nanoparticles are renowned for their exceptional physical and mechanical properties. Their small size grants them distinct properties that can differ from those of bulk materials [3]. These characteristics render nanoparticles highly sought-after for diverse applications across various fields. Among the numerous types of nanoparticles synthesized for zinc, silver, gold, and copper nanoparticles. These nanoparticles have garnered significant attention due to their potential applications and the intriguing properties they possess [4].
Zinc oxide nanoparticles (ZnONPs) have found widespread application in the field of biomedicine, owing to their diverse physical, chemical, and biological characteristics. ZnO nanoparticles possess various characteristics that make them suitable for incorporation in biosensors [5]. By utilizing these nanoparticles, researchers can visualize cellular structures and processes, providing valuable insights into cellular behaviour and function. ZnONPs have found applications in various industries and possess significant health benefits. These nanoparticles have the potential to be an alternative to non-steroidal anti-inflammatory drugs due to their ability to elicit anti-inflammatory responses [6]. Moreover, these nanoparticles have exhibited strong antioxidant properties, indicating their potential for a wide range of therapeutic uses. Bacterial infections represent a substantial public health challenge [7]. Recent research suggests that nanoparticles, particularly ZnONPs, possess antimicrobial properties, photocatalytic activity, increased biocompatibility, and selectivity [8]. This makes them suitable for antimicrobial therapy, as they are durable and heat-resistant. ZnONPs are an essential trace element and micronutrient that plays a crucial role in insulin metabolism, including synthesis, secretion, and integrity [9]. It is important to note that the information provided is based on current research findings and observations regarding the applications and effects of ZnONPs. Ongoing studies may lead to further discoveries and advancements in the field [10].
The synthesis of nanoparticles offers a green, simple, flexible, and sustainable method that has gained significant attention in recent years. This approach allows for the improvement of the physicochemical properties and compatibility of nanoparticles when the synthetic processes are well-controlled [11]. One of the key advantages of using plant extracts is the ease and cost-effectiveness of extracting biomolecules compared to traditional synthesis methods. Most plant extracts contain a diverse array of biomolecules rich in various functional groups, including flavonoids, polyphenols, anthocyanins, terpenoids, and more [12, 13]. The use of plant extracts in nanoparticle synthesis allows for the incorporation of these beneficial biomolecules, potentially enhancing the therapeutic properties of the resulting nanoparticles. The green synthesis of nanoparticles using plant extracts aligns with the principles of sustainability and environmental protection [14]. By utilizing natural resources and avoiding the use of harsh chemicals, this approach minimizes the negative impact on the environment and reduces the generation of hazardous waste. Recently, ZnONPs have been widely used for the production of nanoparticles using plant extracts from different plant species [15]. Plants possess secondary metabolites and biomolecules that act as reducing, stabilizing, and capping agents in the synthesis of nanoparticles. The interaction of nanoparticles with biomolecules is affected by various factors, including size, flexibility, rigidity, core composition, shape, surface properties, purity, stability, biosensors, catalysis, and the production method [16]. These nanoparticles exhibit characteristics like antibacterial and catalytic activity, making them useful in scientific domains and biomedical technology. Metal oxide nanoparticles, due to their substantial surface area, find applications in areas such as antimicrobial, anticancer, antineoplastic, wound healing, and antioxidant properties [10]. Zinc oxide nanoparticles have been synthesized using plant extracts from various sources, including Aquilegia pubiflora [17], Cananga odorata [18], Elaeagnus angustifolia [19] and Salvia officinalis [20]. These ZnO nanoparticles have been studied for their antimicrobial, anticancer, antineoplastic, wound healing, ultraviolet scattering and antioxidant activities. It is a straightforward, convenient, cost-effective, and environmentally friendly approach that minimizes the use of hazardous chemicals [21]. This approach is biologically safe, cost-effective, and environmentally friendly, making it suitable for various applications. Additionally, plants and microorganisms can accumulate and utilize inorganic metal ions, making them valuable in nanoparticle synthesis [22].
Gelatin (GN) hydrogel is an exciting and promising material in the realm of non-toxic biocompatible biopolymers. It is widely used as a surfactant in various nanoformulations due to its remarkable ability to significantly enhance their chemical and physical properties [23, 24]. Gelatin offers a convenient solution for surface stabilization through its ability to be easily applied as a thin coating, enlarging the steric barrier. While various organic coatings have been explored in the field of nanoscience, gelatin as a coating material has received limited attention [25]. Gelatin is widely utilized in biomedical applications because of its ability to biodegrade and its compatibility with living tissues. In previous research, the emphasis has been placed on metal oxides, such as ZnO, TiO2, Ag, and MgO, with gelatin as the capping material [26, 27]. Among these metal oxides, gelatin-coated ZnO stands out due to its useful physical properties, including conductive coating efficacy. They possess essential trace metals, demonstrate consistent behaviour, possess a wide band gap, exhibit photoluminescence, and display predictable anti-oxidant properties. These features contribute to the potential clinical utility of ZnONPs. Reports also indicate that gelatin-bound ZnO nanoparticles are biodegradable, biocompatible, cost-effective, highly permeable, and have antimicrobial properties [28, 29].
Cancer, a leading cause of death worldwide, is characterized by the invasive growth of mutated cells in the body. The widespread prevalence of cancer highlights the urgent need for effective diagnosis and treatment methods [30]. While current treatment options such as surgery, chemotherapy, and radiation have their benefits, they also come with drawbacks such as tumour recurrence, hair loss, fatigue, and potential side effects leading to other diseases. Even after undergoing treatment, there is a risk of cancer spreading throughout the body. In light of this critical situation, there is a growing demand for non-toxic and traditional treatment techniques that offer hope for improved outcomes [31]. Although the application of nanoparticles in cancer research is still in its early stages, there is tremendous potential in emerging technologies to develop reliable anti-cancer treatments using green synthesized nanoparticles [32]. ZnONPs, known for their biocompatibility and biodegradability, have been proposed as a promising option for cancer treatment. ZnONPs have shown promising results in treating various cancer cell lines. Positive outcomes have been observed in PC3 and VCaP cell lines for prostate cancer [33], COLO205 cell lines for colon cancer, MCF7 cell line for breast cancer [34], PA1 cell line for ovarian cancer, and A431 cell line for epidermis carcinoma [35]. The use of green synthesized nanoparticles, including ZnO nanoparticles, holds great potential for cancer treatment. By utilizing the unique properties of nanoparticles, researchers are exploring innovative approaches to deliver targeted therapies, enhance drug delivery, and minimize the side effects associated with traditional treatment methods [36].
The wound-healing process is a complex phenomenon that involves a well-coordinated process with the secretion of many growth factors and hormones essential for the proliferation and migration of various cell types [37]. Impaired wound healing is a significant challenge for individuals, resulting in the development of chronic wounds and foot ulcers. This not only increases healthcare costs but also negatively affects the quality of life of these patients. The complications associated with diabetes and chronic wounds are multifactorial, including chronic inflammation, microbial infections, impaired growth factor secretion, and impaired angiogenesis [38]. Poor wound healing is influenced by a variety of factors, including impaired collagen production and inadequate migration, translocation, and proliferation of fibroblasts and keratinocytes, which are critical for epithelial growth. Recently, nanotechnology-mediated wound healing technology and optimism have received attention. More specifically, various studies have indicated that nanoparticle-loaded biomaterials promote faster wound healing due to their different biodegradability, swelling properties, and biocompatibility [39]. Despite the abundance of biomaterial reports, there is a dearth of hydrogel platforms specifically designed for tissue engineering applications. Several important aspects must be considered when developing biopolymer-based hydrogels for wound healing purposes. Advances in fluid leakage absorption, biocompatibility, scaffolding for cell adhesion, and, if possible, facilitation of mechanical transport for tissue regeneration are emerging [40].
The novelty of this present study, applied the green precipitation method to the synthesis of gelatin-coated zinc oxide nanoparticles (GN/ZnONCs) using Coccinia indica plant seed extract. The synthesized GN/ZnONCs were confirmed by their chemical and physical property characterization techniques. Furthermore, the antibacterial activity of GN/ZnONCs and their antioxidant activities were evaluated. The cytotoxicity of GN/ZnONCs against HT-29 colon cancer cells was analysed. To evaluate the wound-healing activity of the GN/ZnONCs scaffold mechanism, it was evaluated using an in vivo wound healing in animal models.