This presentation gives detailed description of Green Nanotechnology including its principles & significance. Illustrated with examples for its application in various biomedical research fields.
2. WHY GREEN SYNTHESIS?
It removes the complicated protocol.
It can also meet the large-scale production requirement.
Methods using lower and higher plant materials and their products; fungi and sometimes
microorganisms for NPs fabrication are ecofriendly.
Since these materials are easily available and do not require organic solvent as reaction medium, they
are easy to handle and economical.
In major cases the NMs thus synthesized are capped by biomolecules like phenols, tannin, flavonoids
and ascorbate present in the plant materials.
They enhance stability of NPs and also prevent their interaction with atmospheric oxygen. These NMs
are thus not oxidized and can be kept for long period of time without undergoing any change in their
properties.
Green synthetic methods make use of many waste materials like banana peels, lemon rind, dried leaves
of medicinal plants and algae etc. The precursor even in crude form may react with these materials to
produce NPs.
7. 1
2
3
Protocols for nanoparticle synthesis
a) Bottom-up approach for the synthesis of nanoparticles via self-
assembling of various nuclei
b) Top-down approach for the synthesis of nanoparticles via size
reduction
8. Nanoparticles synthesis by flowers and leaves
of plants (Wang et al. 2019)
Parts of plants are thoroughly washed with
the help of tap water and sterilized by
double-distilled water followed by drying at
room temperature.
The dried sample goes to the process of
weighing and crushing.
Afterward, plants extract is mixed with
Milli-Q water as per desired concentration
and boiled with continuous stirring.
The obtained solution is then filtered with
Whatman filter paper, and the part in which
there is a clear solution was useful for
sample (plant extract).
9. Detailed scheme of bio-derived
fabrication/green synthesis of
nanoparticles using lower/higher plant
materials and their products; fungus and
microorganisms
10. Flowchart for synthetic route, characterization and applications of green synthesis of palladium and
platinum nanoparticles from plant’s extract. [Siddiqi and Husen (2016)]
11. Green synthesis of silver nanoparticles by plants extract and AgNO3, its characterization and applicants in
various biomedical fields.
12. Synthetic route of gold nanoparticles by bio-reduction and stabilization of chemical moieties
present in the biogenic complexes.
13. Synthesis of palladium nanoparticles using Catharanthus roseus methanolic leaf extract and
palladium ion
14. Synthesis of Pd
nanoparticles by black
tea leaves (Camellia
sinensis) extract, its
catalytic activity in
Suzuki coupling reaction,
and reduction of 4-
nitrophenol.
15. Biosynthesis of zinc oxide (ZnO) nanoparticles using plants, microorganisms, and others
17. Mechanism for the formation of CuONPs
Authors have argued that the precursor CuSO4
reacts with hydroxyl anion OH-, generated by the
ionization of water molecules and eventually
reduced by phytochemicals present in the seed
extract.
It must be clarified at this stage that:
(a) It is universally known that water is not
ionized until acidified water is electrolyzed.
(b) Cu (OH)2 can be formed only if NaOH or
requisite amount of NH4OH is added to a
copper salt as shown adjacent.
18. However, CuSO4 remains ionized in aqueous
medium or it may form hexaaquo copper
complex, [Cu(H2O)6].
Free Cu2+ ion is then reduced by protein or
polyphenol available in the black bean
extract.
20. Applications of green synthesized nanoparticles in environmental and
biomedical fields
21. Applications of palladium and platinum nanoparticles in chemistry, biology, and
material science fields
22. Recent studies (during 2018–19) on plant-mediated synthesis of Cu-NPs, their morphology, and various applications
24. Sustainable synthesis of cobalt and cobalt oxide nanoparticles and their catalytic and
biomedical applications
25. Silk Biomedical Applications
Tissue Engineering
Drug Delivery Systems
Biomedical Implants
Diagnostic Medical Devices
Silk Intrinsic Properties
Biocompatibility
Controllable Biodegradability
Excellent Mechanical Properties
26. Two approaches used to functionalize silk with
nanomaterials:
(1) Post-functionalization methods
(2) Feeding silkworms with modified diets containing
nanomaterials.
27. Feeding silkworm with Nanomaterials: A Greener Approach
In recent years, several attempts have been made to produce silk fibers with improved properties and new
functionalities by feeding silkworms with modified diets containing nanomaterials.
Nanomaterials possess unique physical, chemical, and biological properties and when combined with silk
can expand its applicability for biomedical applications.
Feeding silkworms with modified diets containing nanomaterials is a greener method of producing
functionalized silk fibers when compared to the alternative post-functionalization methods that include
multistep procedures and toxic chemicals.
The main advantages of using this greener method are related to the reduced usage of resources such as
water, energy, and additional chemicals to spin functional silk fibers, the maintenance of intrinsic silk
properties, the stability of the added new functionalities, and the possibility of large-scale production.
Feeding silkworms with different nanomaterials such as carbon-based nanomaterials, metal and metal oxide
nanoparticles, and quantum dots has led to the production of silk fibers with improved properties (e.g.,
mechanical and thermal) and/or new functionalities (e.g., magnetical and luminescence).
However, nanomaterials concentration, dimensions, and solubility were shown to influence their uptake by
silkworms as well as silk fiber properties.
28. Feeding silkworms with modified diets containing nanomaterials, a green strategy to produce multifunctional
SFs:
(A) Silkworms are fed with nanomaterials sprayed in mulberry leaf or mixed in mulberry powder diet.
(B) Ingested nanomaterials (e.g., carbon nanotubes, nanoparticles, quantum dots) are mixed in the silk
glands of the larvae and incorporated in the SFs, which acquire improved properties and new
functionalities
29. Bacterial synthesized metal and metal salt nanoparticles in
biomedical applications
The green route synthesis exploits diverse reducing and stabilizing agents from
bacterial resources for the successful synthesis of metal nanoparticles.
Bacteria have the unique potential of intra- or extracellular production of inorganic
materials. Bacteria also produce nanoscale dimension of secondary product with
varied morphology. Due to the unique and versatile characteristics of microbial
resistance to most toxic heavy metals, there are great advantages associated with the
production of several metal nanoparticles.
From cell biology study reveals that, the resistance is mainly due to the chemical
detoxification and energy-dependent ion efflux of the cell by functional membrane
proteins as either ATPase or chemiosmoticcations or proton anti-transporters.
The bacterial mediated synthesis of nanoparticles has more importance in
commercial application due its extracellular conversion of soluble toxic inorganic
ions to nontoxic nano-clusters.
30. Possible mechanism involve in the synthesis of nanoparticles by bacterial reductase enzymes and extracellular
proteins
32. Possible mechanism on active role of electron shuttle quinones [redox mediators] in the synthesis of metal nanoparticles
33. Schematic illustration of mechanistic aspects for antibacterial influences of the produced NPs.
bacterial influences of the produced NPs.
37. Cobalt oxide NPs synthesized using polymorphic bacterial templates.
Electron microscopic images and the prepared nanostructured materials.
The bacterial templates could be efficiently eliminated by calcination while retaining the original shape and size.
40. (a) Production of lignin NPs and lignin NPs/PVA composite film.
[ZP: Zeta-potential value, PDI: polydispersity index]
41. (b) Suggested mechanism for UV-shielding and antioxidant activity by applying lignin NPs as the functional additive.
44. Synthesis of nanomaterials
via plants, bacteria & wood
Principle of green synthesis
Advantages of green
synthesis over conventional
methods
SUMMARY
Biomedical Applications of
nanomaterials generated
through green
nanotechnology
45. Let’s join hand for a green future.
The need of today is to foster development but not at the cost of mankind.
Thus, there is an urgent need to promote green nanotechnology for human and
environmental sustainability. The development and commercialization of
viable green nanotechnologies is difficult and require concerted effort from the
researchers, government and other stakeholders. The development of this
environmentally friendly technology can go a long way in accelerating human
welfare.
Green nanotechnology refers to the application of green chemistry and green engineering principles to nanotechnology to evolve methods, materials and techniques for diverse applications like generating energy to non-toxic cleaning products. Green nanotechnology aims to not only contribute nanoproducts that provide solutions to environmental challenges, but also to produce nanomaterials without deteriorating the environment or human health. Green nanotechnology is likely to result in manufacturing processes that are more environmentally friendly and more energy efficient.There are two key aspects to green nanotechnology.(i) Involves nano products that provide solutions to environmental challenges, and(ii) Involves producing nanomaterials and products containing nanomaterials with a view toward minimizing harm to human health or the environment.
Green nanotechnology aims to develop sustainable environmentally-sustainable manufacturing processes and solutions to address burning issues like contamination of aquatic bodies, energy shortages and other areas of environmental concern. Green nanotechnology ‘sustains’ the fourth goal of the National Nanotechnology Initiative i.e. ‘supporting the responsible development of nanotechnology’ by following existing principles of green chemistry and green engineering. It enables nanotechnology to develop in a more responsible and sustainable manner by minimization or elimination of harmful materials used in the synthesis of nanomaterials or by using the products of nanotechnology to regulate these pollutants in the environment. Green nanotechnology is a sustainable approach to nanotechnology from design to production and product use to disposal or recycling. Thus, the eco friendly approach of green nanotechnology limits the risk of producing nanomaterials and minimizes the production of toxic intermediates and end-products. Green nanotechnology also aims to make current manufacturing processes for non-nano materials and products more environmentally friendly.
Conditions for the green synthesis of nanoparticles
Selection of green or environment-friendly solvent
Good reducing agent
Harmless material for stabilization
Synthetic routes for the synthesis of nanoparticles
Physical
Chemical
Biosynthetic routes
Generally, the chemical methods used are too expensive and incorporate the uses of hazardous and toxic chemicals answerable for various risks to the environment (Nath and Banerjee 2013).
The biosynthetic route is a safe, biocompatible, environment-friendly green approach to synthesize nanoparticles using plants and microorganisms for biomedical applications (Razavi et al. 2015).This synthesis can be carried out with fungi, algae, bacteria, and plants, etc. Some parts of plants such as leaves, fruits, roots, stem, seeds have been used for the synthesis of various nanoparticles due to the presence of phytochemicals in its extract which acts like stabilization and reducing agent (Narayanan and Sakthivel 2011).
Silk is a natural protein material spun into fibers through the metamorphosis of silk-producing arthropods such as silkworms. For a long time, humans have been using silk and exploiting its properties for different applications. Textile fabrics and surgical suture materials are two of its oldest and most well-known applications. For more than a decade, silk has been used in the biomedical field, namely, for tissue engineering, drug delivery systems, bioimaging, biomedical implants, and medical devices. Silk produced by the Bombyx mori (B. mori) silkworm is the most commonly used silk worldwide. During its life cycle, the B. mori silkworm passes through four distinct stages: egg, larva, pupa, and adult moth. Silkworms are only fed during their larval stage. Although their main source of food is fresh mulberry leaves, they can also consume artificial diets based on powdered mulberry leaves. Throughout the larval stage, the silkworm molts its skin four times to grow. The larval life is thus divided into five different instars. The fifth instar is the longest, where the larvae show maximum food consumption and higher growth. At the end of this stage, the silkworm starts spinning a cocoon, which is composed of 600−1500 m of fiber. B. mori silk fibers (SFs) are mainly composed of two proteins: fibroin (70%−80%) and sericin (20%−30%).3 The fibroin structure has two main configurations: silk I and silk II. Silk I is characterized by random-coil and α-helix structures and silk II by a β-sheet structure. The β-sheet structure (about 55%) provides strength and stiffness to silk, whereas the random-coil and α-helix structures contribute to its extensibility and toughness. Sericin is a glue-like protein that holds the fibroin fibers together during cocoon formation. For biomedical applications, sericin is often removed from the core SFs, due to its toxicity, by a degumming process using sodium carbonate (Na2CO3). The obtained SFs can be used directly or further dissolved in solvents like lithium bromide (LiBr) to obtain a regenerated silk fibroin aqueous solution which can be processed into multiple forms such as hydrogels, films, micro/ nanospheres, 3D printed structures, scaffolds, fibers, or sponges. Silk fibroin presents excellent mechanical properties, high biocompatibility, and controllable biodegradability, making it appealing in the biomedical field. Although silk fibroin manufacturing can be easily scaled up, has small batch-to-batch variation, and is a time-saving process, the longterm storage of concentrated silk fibroin aqueous solution can be a problem in terms of stability. Moreover, it can be difficult to control its structure and molecular weight, especially after functionalization
Silk is a natural protein material spun into fibers through the metamorphosis of silk-producing arthropods such as silkworms. For a long time, humans have been using silk and exploiting its properties for different applications. Textile fabrics and surgical suture materials are two of its oldest and most well-known applications. For more than a decade, silk has been used in the biomedical field, namely, for tissue engineering, drug delivery systems, bioimaging, biomedical implants, and medical devices. Silk produced by the Bombyx mori (B. mori) silkworm is the most commonly used silk worldwide. During its life cycle, the B. mori silkworm passes through four distinct stages: egg, larva, pupa, and adult moth. Silkworms are only fed during their larval stage. Although their main source of food is fresh mulberry leaves, they can also consume artificial diets based on powdered mulberry leaves. Throughout the larval stage, the silkworm molts its skin four times to grow. The larval life is thus divided into five different instars. The fifth instar is the longest, where the larvae show maximum food consumption and higher growth. At the end of this stage, the silkworm starts spinning a cocoon, which is composed of 600−1500 m of fiber. B. mori silk fibers (SFs) are mainly composed of two proteins: fibroin (70%−80%) and sericin (20%−30%).3 The fibroin structure has two main configurations: silk I and silk II. Silk I is characterized by random-coil and α-helix structures and silk II by a β-sheet structure. The β-sheet structure (about 55%) provides strength and stiffness to silk, whereas the random-coil and α-helix structures contribute to its extensibility and toughness. Sericin is a glue-like protein that holds the fibroin fibers together during cocoon formation. For biomedical applications, sericin is often removed from the core SFs, due to its toxicity, by a degumming process using sodium carbonate (Na2CO3). The obtained SFs can be used directly or further dissolved in solvents like lithium bromide (LiBr) to obtain a regenerated silk fibroin aqueous solution which can be processed into multiple forms such as hydrogels, films, micro/ nanospheres, 3D printed structures, scaffolds, fibers, or sponges. Silk fibroin presents excellent mechanical properties, high biocompatibility, and controllable biodegradability, making it appealing in the biomedical field. Although silk fibroin manufacturing can be easily scaled up, has small batch-to-batch variation, and is a time-saving process, the longterm storage of concentrated silk fibroin aqueous solution can be a problem in terms of stability. Moreover, it can be difficult to control its structure and molecular weight, especially after functionalization
Design strategy for the plant-inspired catechol-chemistry-based self-adhesive, tough, and antibacterial NPs-P-PAA hydrogel.
Formation of radicals by the redox reaction between silver-lignin NPs and ammonium persulfate (APS), stimulating the gelation of the hydrogelunder an ambient environment.
Quinone-catechol reversible reaction maintains dynamic balance.
Scheme of molecular structure of plant-inspired adhesive and tough hydrogel.
Electron spin resonance spectroscopy (ESR) spectra for quinone radical detection.
TEM micrograph demonstrates the core-shell structure of silver-lignin NPs.
High-resolution transmission electron microscopy (HRTEM) micrograph demonstrates the silver-lignin NPs structure.
Scanning electron microscope (SEM) micrograph demonstrates the microfibril structures in the hydrogel. P, pectin; PAA, polyacrylic acid