Faculty Publications
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Item Faster Biomineralization and Tailored Mechanical Properties of Marine-Resource-Derived Hydroxyapatite Scaffolds with Tunable Interconnected Porous Architecture(American Chemical Society service@acs.org, 2019) Hadagalli, K.; Panda, A.K.; Mandal, S.; Basu, B.Although hydroxyapatite (HA)-based porous scaffolds have been widely researched in the last three decades, the development of naturally derived biomimetic HA with a tunable elastic modulus and strength together with faster biomineralization properties has not yet been achieved. To address this specific issue, we report here a scalable biogenic synthesis approach to obtain submicron HA powders from cuttlefish bone. The marine-resource-derived HA together with different pore formers can be conventionally sintered to produce physiologically relevant scaffolds with porous architecture. Depending on pore formers, the scaffolds with a range of porosity of up to 51% with a larger range of pore sizes up to 50 ?m were fabricated. An empirical relationship between the compression strength and the elastic modulus with fractional porosity was established. A combination of moderate compressive strength (12-15 MPa) with an elastic modulus up to 1.6 GPa was obtained from cuttlefish-bone-derived HA with wheat flour as the pore former. Most importantly, the specific HA scaffold supports the faster nucleation and growth of the biomineralized apatite layer with full coverage within 3 days of incubation in simulated body fluid. More importantly, the marine-species-derived HA supported better adhesion and proliferation of murine osteoblast cells than HA sintered using powders from nonbiogenic resources. The spectrum of physical and biomineralization properties makes cuttlefish-bone-derived porous HA a new generation of implantable biomaterial for potential application in cancellous bone regeneration. © 2019 American Chemical Society.Item Hydroxyapatite—a promising sunscreen filter(Springer, 2020) Pal, A.; Hadagalli, K.; Bhat, P.; Goel, V.; Mandal, S.Exposure to ultraviolet (UV) radiation has been known to cause skin cancer, erythema, and sunburn. Continuous efforts have been made to make sunscreens more efficient and non-toxic. Inorganic sunscreens like TiO2 and ZnO are continued to be used for a few decades, and they are efficient in giving protection against harmful UV radiation, but they are photochemically active as well. They generate free radicals upon irradiation, which leads to reactive oxygen species (ROS) generation which is harmful to the human skin. Hydroxyapatite (HA) is a biocompatible material as it has a composition the same as the mineral content of the human bone; therefore, it is suitable for the dermatological application. Though HA itself does not provide protection against UV, studies on doped HA with various ions showed excellent performance. Pure HA absorbs only between 200 and 340 nm, with an intense band below 247 nm. HA doped with bivalent Zn2+, Fe2+, and trivalent Fe3+ and Cr3+, showed absorbance in the entire UV region. TiO2 provides absorbance in the entire UV range, while ZnO does so only in UVA. Compared to HA (refractive index, n = 1.6), TiO2 (n = 2.6) and ZnO (n = 1.9) have higher refractive index, which gives unwanted whitening effect. Additional properties can be brought in HA composites by adding material while retaining their individual properties. As HA is not photocatalytic, it does not lead to a generation of free radicals. This paper throws light on several aspects of HA-based sunscreen filters as an emerging future cosmetic material, and brief analysis and conclusions. © 2019, Australian Ceramic Society.Item Structural, compositional and spectral investigation of prawn exoskeleton nanocomposite: UV protection from mycosporine-like amino acids(Elsevier Ltd, 2020) Hadagalli, K.; Kumar, R.; Mandal, S.; Basu, B.The present work explores the use of marine resourced prawn exoskeleton/shell as a new class of naturally occurring composite containing UV absorbing proteins. Mycosporine-like amino acids with a central aromatic ring in the exoskeleton/shell of naturally occurring prawns (Fenneropenaeus Indicus) offer excellent UV protection. The architecture of shell composite constitutes a matrix of chitin-proteins with distinct reinforcements such as spherical calcites (CaCO3), microscopic proteins, and traces of hydroxides/oxides of magnesium. The presence of tryptophan, phenylalanine, and tyrosine, forming the basic building blocks of mycosporines, is confirmed by structural, compositional, and microscopic studies on prawn shells. The UV spectroscopic signatures at 290 and 320 nm provides strong evidence for the highest UV absorption. UV absorption attributes to the presence of mycosporine-like amino acids. Hence, the current exploration of naturally occurring prawn shells directs towards an additive-free sunscreen filter without the generation of detrimental free radicals. © 2020 Elsevier B.V.Item Improved Fracture Toughness and Crack Arrest Ability of Graphene–Alumina Nanocomposite(Springer, 2021) Akhil Raj, V.R.; Hadagalli, K.; Jana, P.; Mandal, S.In this work, high fracture toughness graphene–alumina composite was developed through a novel chemical method using boehmite and graphene, which is followed by extrusion and consolidation. The mixed precursors were consolidated by sintering at 1550 °C in a nitrogen atmosphere. The plate-like structures of boehmite form ?-alumina; meanwhile, graphene particles at the grain boundaries hinder the growth of alumina grains. The graphene reinforcement was bonded to ?-alumina matrix by van der Waals forces. The XRD pattern reveals the presence of graphene with a plane (002) along with ?-alumina. Properties such as fracture toughness (5.6 ± 0.01 MPa m0.5), Vickers hardness (1872 ± 25 kgf/mm2) and true density (3.8 g/cm3) were achieved in 0.5 wt.% graphene–alumina composite when compared to ?-alumina with fracture toughness (5.3 ± 0.1 MPa m0.5), Vickers hardness (1984 ± 28 kgf/mm2) and true density (3.91 g/cm3). The bridging and deviation of cracks in 0.5 wt.% graphene–alumina composite are attributed to the anchoring and dissipation of energy during crack growth, which enhances the fracture toughness, whereas ?-alumina exhibits failure caused by linear crack propagation. Meanwhile, the slight decrease in Vickers hardness and true density of 0.5 wt.% graphene–alumina composite is due to the tribological and low-density properties of graphene. The obtained properties of composite could be suitable in high-temperature, wear-resistant applications such as crucibles, bearings, etc. © 2021, ASM International.Item Effect of Fe3+ substitution on the structural modification and band structure modulated UV absorption of hydroxyapatite(Blackwell Publishing Ltd, 2021) Hadagalli, K.; Shenoy, S.; Shakya, K.R.; Manjunath, G.; Tarafder, K.; Mandal, S.; Basu, B.The effect of Fe3+ ionic substitution in hydroxyapatite (Ca10-xFex(PO4)6(OH)2) was studied using structural modifications, resulting in an improvement in UV absorption through a tailored optical band structure. Ca2+ of HA being larger compared to Fe3+ contributes to the shrinkage of the lattice. Undoped HA has a peak at 1085 cm?1 (?3 PO43?) which is shifted to 1033 cm?1 for Fe-HA, because of the perturbation in HA structure. An improvement of UV absorption in the entire UVA and UVB range with an increase in Fe content because of a decrease in bandgap from 5.9 eV to 2.1 eV with undoped and doped HA. Theoretically obtained band gap and optical behaviour of the systems are well correlated with the experimental findings. Moreover, the use of marine biowaste from cuttlefish bone, as the source of HA; low cost and promising UV absorption can have a potential application as UV protective sunscreen filters. © 2020 The American Ceramic SocietyItem Preparation and structural characteristics of biphasic calcium phosphates from prawn shell bio-waste(Taylor and Francis Ltd., 2023) Satish, P.; Salian, A.; Hadagalli, K.; Mandal, S.The major objective of the work is to explore the mechanical properties of biphasic calcium phosphates (BCP), a biomaterial derived from marine resources like prawn (Fenneropenaeus Indicus) shell biowaste through wet chemical treatment of CaO. We report the BCP, a mixture of hydroxyapatite and octa calcium phosphate from prawn shell biowaste using wet chemical synthesis at 80°C under pH 10. XRD of BCP revealed the coexistence of secondary phases like β-TCP and α-TCP along with HA upon sintering at different temperatures. Furthermore, the SEM and EDS opened well-sintered uniaxial grains and the presence of trace elements like Fe, Mg, Si, and Na. The specimens sintered at 1100°C showed the highest compression strength of 56.8 MPa due to MgO at the grain boundaries, which plays an important role in grain boundary diffusion. Therefore, the prawn shell biowaste-derived BCP has good mechanical properties, making them suitable materials for high-strength bone substitutes. © 2023 Institute of Materials, Minerals and Mining. Published by Taylor & Francis on behalf of the Institute.Item Hydroxyapatite–Clay Composite for Bone Tissue Engineering: Effective Utilization of Prawn Exoskeleton Biowaste(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Satish, P.; Hadagalli, K.; Praveen, L.L.; Nowl, M.S.; Seikh, A.H.; Alnaser, I.A.; Abdo, H.S.; Mandal, S.Hydroxyapatite (HA, Ca10(PO4)6(OH)2)-based porous scaffolds have been widely investigated in the last three decades. HA, with excellent biocompatibility and osteoconductivity, has made this material widely used in bone tissue engineering. To improve the mechano-biological properties of HA, the addition of clay to develop HA-based composite scaffolds has gained considerable interest from researchers. In this study, a cost-effective method to prepare a HA–clay composite was demonstrated via the mechanical mixing method, wherein kaolin was used because of its biocompatibility. Prawn (Fenneropenaeus indicus) exoskeleton biowaste was utilized as a raw source to synthesize pure HA using wet chemical synthesis. HA–clay composites were prepared by reinforcing HA with 10, 20, and 30 wt.% of kaolin via the mechanical mixing method. A series of characterization tools such as XRD, FTIR, Raman, and FESEM analysis confirmed the phases and characteristic structural and vibrations bonds along with the morphology of sintered bare HA, HA–kaolin clay composite, and kaolin alone, respectively. The HA–clay composite pellets, uniaxially pressed and sintered at 1100 °C for 2 h, were subjected to a compression test, and an enhancement in mechanical and physical properties, with the highest compressive strength of 35 MPa and a retained open porosity of 33%, was achieved in the HA–kaolin (20 wt.%) clay composite, in comparison with bare HA. The addition of 20% kaolin to HA enhanced its compressive strength by 33.7% and increased its open porosity by 19% when compared with bare HA. The reinforcement of HA with different amounts (10, 20, 30 wt.%) of kaolin could open up a new direction of preparing biocomposite scaffolds with enhanced mechanical properties, improved wear, and better cell proliferation in the field of bone tissue engineering. © 2023 by the authors.Item Effect of Temperature on Solid-State Reaction of Prawn Shell-Derived Phase-Pure β-Tricalcium Phosphate(Springer, 2024) Satish, P.; Praveen, L.L.; Gautam, V.; Hadagalli, K.; Mandal, S.Over the past three decades, bioresorbable ceramics such as beta-tricalcium phosphate (β-TCP)-based porous scaffolds have been extensively studied. β-TCP-based scaffolds or cements for bone tissue applications have proved to be an outstanding alternative to repair and regenerate bone tissue defects caused by trauma or injury. In this study, an investigation on submicron β-TCP powders derived from prawn shell (Fenneropenaeus indicus, a source of marine biowaste) via solid-state reaction approach was carried out, which has calcite (CaCO3) in its exoskeleton (nonedible). The prawn shell-derived β-TCP can be prepared conventionally with dicalcium phosphate (CaHPO4) at different temperatures 900, 1000, 1100, and 1200 °C. The EDX spectra detect the Ca:P ratio of 1.5 confirming the formation of pure β-TCP at 1100 °C, which is in complete agreement with theoretical ratio. X-ray diffraction pattern revealed the phase-pure crystalline rhombohedral crystal structure of β-TCP with an average crystallite size of ~ 25.8 nm, prepared at 1100 °C. The field emission scanning electron microscopy images showed a homogeneous distribution of β-TCP powders with an average grain size of 3.07 µm at 1100 °C. Furthermore, Raman spectroscopy and Fourier transform infrared spectroscopy confirm the characteristics peaks of β-TCP. Differential scanning calorimetry and thermogravimetric analysis are performed to study the thermal behavior of the initial precursors mixture to synthesize β-TCP. β-TCP scaffolds sintered at 1100 °C exhibited compressive strength of ~ 6.2 MPa, for which Ca/P ratio is 1.51. Biodegradation study conducted on β-TCP scaffolds sintered at 1100 °C has shown slow degradation rate up to 5 days. Therefore, the prawn shell-derived β-TCP has physical and morphological properties which projects it as a promising implantable biomaterial for synthetic bone graft substitutes. © ASM International 2024.Item Enhancing Strength Properties of Hydroxyapatite Composites with Bentonite Clay(Taylor and Francis Ltd., 2025) Satish, P.; Hadagalli, K.; Nowl, M.S.; Siddeswara, R.; Kalikeri, S.; Mandal, S.The main inorganic component of human hard tissues is hydroxyapatite (HA, Ca10(PO4)6(OH)2) and the mechanical and biological performance of HA can be improved by incorporating clay minerals to create HA-clay composite scaffolds. This study demonstrates a high-strength biocomposite of HA and bentonite with a significant reduction of open porosity, considering bentonite clay for its biocompatibility. Prawn shells (Fenneropenaeus indicus - marine resource) were utilized as a sustainable source of calcium to synthesize high-purity HA through a wet-chemical process, offering an innovative approach to valorize bio-waste. HA-bentonite clay composites were made by compacting 10-40 wt% of bentonite clay with HA using uniaxial pressing, followed by sintering at 1100°C for 2 h. Characterization techniques like X-ray diffraction, Raman, Fourier transform infrared spectroscopy and field emission scanning electron microscopy verified the phases, structures, vibrational bonds and morphology of the synthesized materials. Energy dispersive X-ray spectroscopy and inductively coupled plasma mass spectrometry analysis were performed for elemental composition and heavy metal detection, respectively. The HA-bentonite (30 wt%) composite achieved an exceptional compressive strength of 155 MPa and an open porosity of 7%, surpassing bare HA. Adding 30% bentonite increased compressive strength six fold and decreased open porosity by 51% compared to bare HA. This novel approach to HA-bentonite scaffolds promises enhanced wear resistance and cellular proliferation in bone tissue engineering. © 2025 Indian Ceramic Society.