Biological synthesis of gold nanocubes from Bacillus licheniformis

Microorganisms play an important role in the eco-friendly synthesis of metal nanoparticles. This study illustrates the synthesis of gold nanocubes using the bacterium Bacillus licheniformis after 48 h of incubation at room temperature. The morphology of the samples was analyzed using scanning electron microscopy (SEM) and the particles formed were characterized to be nanocubes. The size of gold nanocubes in aqueous solution has been calculated using UV–Vis spectroscopy, XRD and SEM measurements. The nanoparticles are found to be polydisperse nanocubes in the size range 10–100 nm.     

Counter ions and temperature incorporated tailoring of biogenic gold nanoparticles

Despite the vast research being conducted on the development of biosynthetic procedures, the process is limited owing to the unavailability of modes to control the size and shape of the biosynthesized nanoparticles. In this study, we investigate the size and shape control of gold nanoparticles synthesized by leaf extract of Piper betle (PBE). The effects of various counter ions, temperatures, pH and reaction times on the morphology of gold nanoparticles are also scrutinized. Results from this study indicate that the presence of iodine during biosynthesis leads to the formation of spherical gold nanoparticles and induces the presence of bromine-emanating, truncated nanoplatelets. Spherical nanoparticles are formed with increasing incubation temperature. pH 3 was found to be the optimum for nanoparticles synthesis. The presence of phosphates, sulphates and nitrates increases the productivity of nanoparticles. ICP analysis revealed complete reduction of AuCl₄⁻ ions within 48 h of the reaction. The use of plant extract for rapid synthesis represents a novel and environmentally friendly approach for the fabrication of gold nanoparticles and nanoplatelets, as an alternative to chemical methods.     

Fungus mediated synthesis of gold nanoparticles and their conjugation with genomic DNA isolated from Escherichia coli and Staphylococcus aureus

Biological systems employing microorganisms have been used as an alternative to conventional chemical techniques for synthesizing gold nanoparticles. In the present study, gold nanoparticles have been synthesized from the supernatant broth (SB) and live cell filtrate (LCF) of the industrially important fungus Penicillium rugulosum. Additionally, potato dextrose broth (PDB) medium which is used for the growth of the fungus has also been able to synthesize gold nanoparticles. The size of the particles has been investigated by Bio-TEM before purification as well as after purification to find the difference in morphology pattern of the nanoparticles. Different characterization techniques like X-ray diffraction (XRD), infra-red (FTIR), X-ray photoelectron (XPS) and UV–vis spectroscopy have been used for analysis of the particles. SB of the fungus has yielded nanoparticles with better morphology and hence further optimization studies were conducted for controlling the size and shape of the above by altering pH and concentration of gold salt. A pH range of 4–6 has favored the synthesis process whereas increasing concentration of gold salt (beyond 2 mM) has resulted in the formation of bigger sized and aggregated nanoparticles. The optimized nanoparticles have been used to conjugate with isolated genomic DNA of bacteria Escherichia coli and Staphylococcus aureus. Visual observation of agarose gel electrophoresis images confirmed the binding of gold nanoparticles (4 μL and 6 μL) with isolated DNA (2 μL) fragments of both the organisms. The slight red shift of the surface plasmon (SP) band and minor aggregations noticed in Bio-TEM images for the DNA conjugated gold nanoparticles indicates that the genomic DNA could stabilize the particles against aggregation owing to negatively charged phosphate backbone.     

Mycocrystallization of gold ions by the fungus Cylindrocladium floridanum

The size and morphology determines the thermodynamic, physical and electronic properties of metal nanoparticles. The extracellular synthesis of gold nanoparticles by fungus, Cylindrocladium floridanum, which acts as a source of reducing and stabilizing agent has been described. The synthesized nanoparticles were characterized using techniques such as UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray analysis (EDAX), and high-resolution transmission electron microscopy (HR-TEM). Based on the evidence of HR-TEM, the synthesized particles were found to be spherical with an average size of 19.05 nm. Powder XRD pattern proved the formation of (111)-oriented face-centered cubic crystals of metallic gold. This microbial approach by fungus for the green synthesis of spherical gold nanoparticles has many advantages such as economic viability, scaling up and environment friendliness.     

Biosynthesis of silver and gold nanoparticles using thermophilic bacterium Geobacillus stearothermophilus

Nanomaterials have assumed a great deal of importance as they often display unique and considerably modified physical, chemical and biological properties as compared to their counterparts of the macroscale. In this study, biogenic synthesis of silver and gold nanoparticles by Geobacillus stearothermophilus has been attempted. The exposure of G. stearothermophilus cell free extract to the metal salts leads to the formation of stable silver and gold nanoparticles in the solution. These nanoparticles were characterized by UV–Vis spectra, FTIR, TEM, and XRD. The silver and gold nanoparticles have absorption maxima at 423 nm and 522 nm respectively. The TEM micrograph revealed the formation of polydispersed particles in the case of silver nanoparticles and monodispersed particles with respect to the gold nanoparticles. High stability of the nanoparticle solution could be attributed to the secretion of certain capping proteins by the bacterium in the reaction mixture. The involvement of these proteins was confirmed by FTIR and SDS PAGE.     

Exploitation of marine bacteria for production of gold nanoparticles

Background

Gold nanoparticles (AuNPs) have found wide range of applications in electronics, biomedical engineering, and chemistry owing to their exceptional opto-electrical properties. Biological synthesis of gold nanoparticles by using plant extracts and microbes have received profound interest in recent times owing to their potential to produce nanoparticles with varied shape, size and morphology. Marine microorganisms are unique to tolerate high salt concentration and can evade toxicity of different metal ions. However, these marine microbes are not sufficiently explored for their capability of metal nanoparticle synthesis. Although, marine water is one of the richest sources of gold in the nature, however, there is no significant publication regarding utilization of marine micro-organisms to produce gold nanoparticles. Therefore, there might be a possibility of exploring marine bacteria as nanofactories for AuNP biosynthesis.

Results

In the present study, marine bacteria are exploited towards their capability of gold nanoparticles (AuNPs) production. Stable, monodisperse AuNP formation with around 10?nm dimension occur upon exposure of HAuCl₄ solution to whole cells of a novel strain of Marinobacter pelagius, as characterized by polyphasic taxonomy. Nanoparticles synthesized are characterized by Transmission electron microscopy, Dynamic light scattering and UV-visible spectroscopy.

Conclusion

The potential of marine organisms in biosynthesis of AuNPs are still relatively unexplored. Although, there are few reports of gold nanoparticles production using marine sponges and sea weeds however, there is no report on the production of gold nanoparticles using marine bacteria. The present work highlighted the possibility of using the marine bacterial strain of Marinobacter pelagius to achieve a fast rate of nanoparticles synthesis which may be of high interest for future process development of AuNPs. This is the first report of AuNP synthesis by marine bacteria.     

Effect of gemini surfactant (16-6-16) on the synthesis of silver nanoparticles: A facile approach for antibacterial application

In this report, we describe the effect of Gemini surfactants1, 6-Bis (N, N-hexadecyldimethylammonium) adipate (16-6-16) on synthesis, stability and antibacterial activity of silver nanoparticles (AgNPs). The stabilizing effect of Gemini surfactant and aggregation behavior of AgNPs was evaluated by plasmonic property and morphology of the AgNPs were characterized by UV–vis spectroscopy, Dynamic Light Scattering (DLS), X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM) and Energy dispersive X-ray analysis (EDX) techniques. Interestingly, the formation of quite mono-dispersed spherical particles was found. Apart from the stabilizing role, the Gemini surfactant has promoted the agglomeration of individual AgNPs in small assemblies whose Plasmon band features differed from those of the individual nanoparticles. The antibacterial activity of the synthesized AgNPs on Gram-negative and Gram-positive bacterium viz., E. coli and S. aureus was carried out by plate count, growth kinetics and cell viability assay. Furthermore, the mechanism of antibacterial activity of AgNPs was tested by Zeta potential and DLS analysis, to conclude that surface charge of AgNPs disrupts the cells causing cell death.     

Relationship between salt tolerance and nanoparticle synthesis by <Emphasis Type="Italic">Williopsis saturnus</Emphasis> NCIM 3298

This work describes cell associated and extracellular synthesis of nanoparticles by the yeast, Williopsis saturnus. The yeast was able to grow in the absence and presence of sodium chloride (NaCl) and form nanoparticles in a cell associated manner. The content of melanin, a stress-associated pigment was found to be progressively greater in the presence of increasing concentrations of NaCl. With higher quantities of melanin (extracted from yeast cells grown in the presence of 4% of NaCl), smaller sized nanoparticles were obtained. This is the first report on understanding the relationship between halotolerance, production of a stress-related pigment (melanin) and synthesis of nanoparticles with antioxidant properties by using W. saturnus as a model system. The cell free extracts derived from cultures grown in the absence of NaCl were able to mediate extracellular synthesis of gold and silver nanoparticles and the biomolecule mediating nanoparticle synthesis was identified to be a glycolipid. Extracellularly synthesized gold nanoparticles displayed good catalytic activity and rapidly mediated the reduction of 4-nitrophenol to 4-aminophenol.     

Microbial synthesis of gold nanoparticles using the fungus <Emphasis Type="Italic">Penicillium brevicompactum</Emphasis> and their cytotoxic effects against mouse mayo blast cancer C<Subscript>2</Subscript>C<Subscript>12</Subscript> cells

Microorganisms, their cell filtrates, and live biomass have been utilized for synthesizing various gold nanoparticles. The shape, size, stability as well as the purity of the bio synthesized nanoparticles become very essential for application purpose. In the present study, gold nanoparticles have been synthesized from the supernatant, live cell filtrate, and biomass of the fungus Penicillium brevicompactum. The fungus has been grown in potato dextrose broth which is also found to synthesize gold nanoparticles. The size of the particles has been investigated by Bio-TEM before purification, following purification and after storing the particles for 3 months under refrigerated condition. Different characterization techniques like X-ray diffraction, Fourier transform infrared spectroscopy, and UV–visible spectroscopy have been used for analysis of the particles. The effect of reaction parameters such as pH and concentration of gold salt have also been monitored to optimize the morphology and dispersity of the synthesized gold nanoparticles. A pH range of 5 to 8 has favored the synthesis process whereas increasing concentration of gold salt (beyond 2 mM) has resulted in the formation of bigger sized and aggregated nanoparticles. Additionally, the cytotoxic nature of prepared nanoparticles has been analyzed using mouse mayo blast cancer C₂C₁₂ cells at different time intervals (24, 48, and 72 h) of incubation period. The cells are cultivated in Dulbecco’s modified Eagle’s medium supplemented with fetal bovine serum with antibiotics (streptopenicillin) at 37°C in a 5% humidified environment of CO₂. The medium has been replenished every other day, and the cells are subcultured after reaching the confluence. The viability of the cells is analyzed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide method.     

Gold Nanoparticles Attenuates Antimycin A-Induced Mitochondrial Dysfunction in MC3T3-E1 Osteoblastic Cells

Gold nanoparticles have shown promising biological applications due to their unique properties. Understanding the interaction mechanisms between nanomaterials and biological cells is important for the control and manipulation of these interactions for biomedical applications. In the present study, we investigated the effects of gold nanoparticles on the differentiation of osteoblastic MC3T3-E1 cells and antimycin A-induced mitochondrial dysfunction. The results showed that gold nanoparticles (5, 10, and 20 nm) caused a significant elevation of cell growth, alkaline phosphatase activity, collagen synthesis, and osteocalcin content in the cells (P?<?0.05). Moreover, pretreatment with gold nanoparticles prior to antimycin A exposure significantly reduced antimycin A-induced cell damage by preventing mitochondrial membrane potential dissipation, complex IV inactivation, ATP loss, cytochrome c release, cardiolipin peroxidation, and reactive oxygen species generation. Taken together, our study indicated that gold nanoparticles may improve the differentiation and have protective effects on mitochondrial dysfunction of osteoblastic cells.     

Macrophomina phaseolina: microbased biorefinery for gold nanoparticle production

Biofabrication of nanoparticles via the principles of green nanotechnology is a key issue addressed in nanobiotechnology research. There is a growing need for development of a synthesis method for producing biocompatible stable nanoparticles in order to avoid adverse effects in medical applications. We report the use of simple and rapid biosynthesis method for the preparation of gold nanoparticles using Macrophomina phaseolina (Tassi) Goid, a soil-borne pathogen. The effect of pH and temperature on the synthesis of gold nanoparticles by M. phaseolina was also assessed. Different techniques like UV-Visible Spectroscopy, Transmission Electron Microscopy (TEM), Dynamic light scattering (DLS) measurements, Fourier transform infrared (FTIR), and EDX were used to characterize the gold nanoparticles. The movement of these gold nanoparticles inside Escherichia coli (ATCC11103) along with effect on growth and viability was evaluated. The biogenic gold nanoparticle was synthesized at 37 °C temperature and neutral pH. UV-Visible Spectroscopy, TEM, EDX, and DLS measurements confirm the formation of 14 to 16 nm biogenic gold nanoparticles. FTIR substantiates the presence of protein capping on Macrophomina phaseolina-mediated gold nanoparticles. The non-toxicity of gold nanoparticles was confirmed by the growth and viability assay while the TEM images validated the entry of gold nanoparticles without disrupting the structural integrity of E. coli. Biogenic method for the synthesis of nanoparticles using fungi is novel, efficient, without toxic chemicals. These biogenic gold nanoparticles themselves are nontoxic to the microbial cells and offer a better substitute for drug delivery system.

     

Carotenoid stabilized gold and silver nanoparticles derived from the Actinomycete Gordonia amicalis HS-11 as effective free radical scavengers

The Actinomycete Gordonia amicalis HS-11 produced orange pigments when cultivated on n-hexadecane as the sole carbon source. When cells of this pigmented bacterium were incubated with 1 mM chloroauric acid (HAuCl₄) or silver nitrate (AgNO₃), pH 9.0, at 25 °C, gold and silver nanoparticles, respectively, were obtained in a cell associated manner. It was hypothesized that the pigments present in the cells may be mediating metal reduction reactions. After solvent extraction and High Performance Liquid Chromatography, two major pigments displaying UV–vis spectra characteristic of carotenoids were isolated. These were identified on the basis of Atmospheric Pressure Chemical Ionization Mass Spectrometry (APCI-MS) in the positive mode as 1′-OH-4-keto-γ-carotene (Carotenoid K) and 1′-OH-γ-carotene (Carotenoid B). The hydroxyl groups present in the carotenoids were eliminated under alkaline conditions and provided the reducing equivalents necessary for synthesizing nanoparticles. Cell associated and carotenoid stabilized nanoparticles were characterized by different analytical techniques. In vitro free radical scavenging activities of cells (control, gold and silver nanoparticle loaded), purified carotenoids and carotenoid stabilized gold and silver nanoparticles were evaluated. Silver nanoparticle loaded cells and carotenoid stabilized silver nanoparticles exhibited improved nitric oxide (NO) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activities compared to their control and gold counterparts. This paper thus reports cell associated nanoparticle synthesis by G. amicalis, describes for the first time the role of carotenoid pigments in metal reduction processes and demonstrates enhanced free radical scavenging activities of the carotenoid stabilized nanoparticles.     

Multifunctional Hybrid Fe2O3-Au Nanoparticles for Efficient Plasmonic Heating

One of the most widely used methods for manufacturing colloidal gold nanospherical particles involves the reduction of chloroauric acid (HAuCl₄) to neutral gold Au(0) by reducing agents, such as sodium citrate or sodium borohydride. The extension of this method to decorate iron oxide or similar nanoparticles with gold nanoparticles to create multifunctional hybrid Fe₂O₃-Au nanoparticles is straightforward. This approach yields fairly good control over Au nanoparticle dimensions and loading onto Fe₂O₃. Additionally, the Au metal size, shape, and loading can easily be tuned by changing experimental parameters (e.g., reactant concentrations, reducing agents, surfactants, etc.). An advantage of this procedure is that the reaction can be done in air or water, and, in principle, is amenable to scaling up. The use of such optically tunable Fe₂O₃-Au nanoparticles for hyperthermia studies is an attractive option as it capitalizes on plasmonic heating of gold nanoparticles tuned to absorb light strongly in the VIS-NIR region. In addition to its plasmonic effects, nanoscale Au provides a unique surface for interesting chemistries and catalysis. The Fe₂O₃ material provides additional functionality due to its magnetic property. For example, an external magnetic field could be used to collect and recycle the hybrid Fe₂O₃-Au nanoparticles after a catalytic experiment, or alternatively, the magnetic Fe₂O₃ can be used for hyperthermia studies through magnetic heat induction. The photothermal experiment described in this report measures bulk temperature change and nanoparticle solution mass loss as functions of time using infrared thermocouples and a balance, respectively. The ease of sample preparation and the use of readily available equipment are distinct advantages of this technique. A caveat is that these photothermal measurements assess the bulk solution temperature and not the surface of the nanoparticle where the heat is transduced and the temperature is likely to be higher.     

Bactericidal effect of silver nanoparticles against multidrug-resistant bacteria

Infections caused by drug-resistant microorganisms result in significant increases in mortality, morbidity, and cost related to prolonged treatments. The antibacterial activity of silver nanoparticles against some drug-resistant bacteria has been established, but further investigation is needed to determine whether these particles could be an option for the treatment and prevention of drug-resistant microbial infections. Hence, we challenged different drug-resistant pathogens of clinical importance (multidrug-resistant Pseudomonas aeruginosa, ampicillin-resistant Escherichia coli O157:H7 and erythromycin-resistant Streptococcus pyogenes) with a suspension of silver nanoparticles. By means of a luciferase-based assay, it was determined that silver nanoparticles (1) inactivate a panel of drug-resistant and drug-susceptible bacteria (Gram positive and Gram negative), (2) exert their antibacterial activity through a bactericidal rather than bacteriostatic mechanism, and (3) inhibit the bacterial growth rate from the time of first contact between the bacteria and the nanoparticles. Additionally, strains with a resistant phenotype to silver nanoparticle were developed and used to explore the bactericidal mode of action of silver nanoparticles. Through a Kirby–Bauer test, it was shown that silver nanoparticles’ general mechanism of bactericidal action is based on inhibition of cell wall synthesis, protein synthesis mediated by the 30s ribosomal subunit, and nucleic acid synthesis. Our data suggest that silver nanoparticles are effective broad-spectrum biocides against a variety of drug-resistant bacteria, which makes them a potential candidate for use in pharmaceutical products and medical devices that may help to prevent the transmission of drug-resistant pathogens in different clinical environments.     

Green synthesis of gold nanoparticles using Nyctanthes arbortristis flower extract

The present study explores the reducing and capping potentials of ethanolic flower extract of the plant Nyctanthes arbortristis for the synthesis of gold nanoparticles. The extract at different volume fractions were stirred with HAuCl₄ aqueous solution at 80 °C for 30 min. The UV–Vis spectroscopic analysis of the reaction products confirmed successful reduction of Au³⁺ ions to gold nanoparticles. Transmission electron microscope (TEM) revealed dominant spherical morphology of the gold nanoparticles with an average diameter of 19.8 ± 5.0 nm. X-ray diffraction (XRD) study confirmed crystalline nature of the synthesized particles. Fourier transform infra-red (FTIR) and nuclear magnetic resonance (NMR) analysis of the purified and lyophilized gold nanoparticles confirmed the surface adsorption of biomolecules during preparation and caused long-term (6 months) stability. Low reaction temperature (25 °C) favored anisotropy. The strong reducing power of the flower extract can also be tested in the green synthesis of other metallic nanoparticles.     

Fine-Tuning the Antimicrobial Profile of Biocompatible Gold Nanoparticles by Sequential Surface Functionalization Using Polyoxometalates and Lysine

Antimicrobial action of nanomaterials is typically assigned to the nanomaterial composition, size and/or shape, whereas influence of complex corona stabilizing the nanoparticle surface is often neglected. We demonstrate sequential surface functionalization of tyrosine-reduced gold nanoparticles (AuNPs^Tyr) with polyoxometalates (POMs) and lysine to explore controlled chemical functionality-driven antimicrobial activity. Our investigations reveal that highly biocompatible gold nanoparticles can be tuned to be a strong antibacterial agent by fine-tuning their surface properties in a controllable manner. The observation from the antimicrobial studies on a gram negative bacterium Escherichia coli were further validated by investigating the anticancer properties of these step-wise surface-controlled materials against A549 human lung carcinoma cells, which showed a similar toxicity pattern. These studies highlight that the nanomaterial toxicity and biological applicability are strongly governed by their surface corona.     

Biogenic synthesis of gold nanoparticles by marine endophytic fungus-Cladosporium cladosporioides isolated from seaweed and evaluation of their antioxidant and antimicrobial properties

Marine endophytes are the most untapped group of microorganisms having enormous applications in pharmaceutical and cosmetra id="spar0060">Marine endophytes are the most untapped group of microorganisms having enormous applications in pharmaceutical and cosmetic industries. In the present study, we have optimized a method for biogenic synthesis of gold nanoparticles (AuNPs) from Cladosporium cladosporioides, an endophytic fungus of the seaweed, Sargassumwightii. The identity of the fungus was established by the 18 s rRNA and ITS sequence. The AuNPs synthesized using C. cladosporioides were characterized by UV–vis spectrophotometer, Field Emission Scanning Electron Microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Dynamic light scattering, Atomic force microscopy, and Energy dispersive X-ray spectroscopic studies. They were tested for free radical scavenging activity (DPPH and FRAP assay) and antimicrobial activity against a panel of pathogenic microorganisms. The AuNps were within 100 nm as confirmed by the above methods. An attempt was made to understand the mechanism of the gold nanoparticle synthesis using the fungal extract. The present study shows the involvement of NADPH-dependent reductase and phenolic compounds in the bioreduction of the gold metal salts to nanoparticles. The AuNPs showed significant antioxidant as well as the antimicrobial activity. Hence, this study has shown a great potential for the development of a cost effective antimicrobial treatment utilizing biogenic gold nanoparticles.     

Antimicrobial Activities of Silver Nanoparticles Synthesized by Using Water Extract of Arnicae anthodium

Green synthesis of nanoparticles has gained significant importance in recent years and has become the one of the most preferred methods. Also, green synthesis of nanoparticles is valuable branch of nanotechnology. Plant extracts are eco-friendly and can be an economic option for synthesis of nanoparticles. This study presents method the synthesis of silver nanoparticles using water extract of Arnicae anthodium. Formation of silver nanoparticles was confirmed by UV–visble spectroscopy, Fourier transform infrared spectroscopy and total reflection X-ray fluorescence analysis. The morphology of the synthesized silver nanoparticles was verified by SEM–EDS. The obtained silver nanoparticles were used to study their antimicrobial activity.     

Extracellular synthesis of gold bionanoparticles by <Emphasis Type="Italic">Nocardiopsis</Emphasis> sp. and evaluation of its antimicrobial,antioxidant and cytotoxic activities

Advancement of biological process for the synthesis of bionanoparticles is evolving into a key area of research in nanotechnology. The present study deals with the biosynthesis, characterization of gold bionanoparticles by Nocardiopsis sp. MBRC-48 and evaluation of their antimicrobial, antioxidant and cytotoxic activities. The gold bionanoparticles obtained were characterized by UV–visible spectroscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy (TEM). The synthesized gold bionanoparticles were spherical in shape with an average of 11.57 ± 1.24 nm as determined by TEM and dynamic light scattering (DLS) particle size analyzer, respectively. The biosynthesized gold nanoparticles exhibited good antimicrobial activity against pathogenic microorganisms. It showed strong antioxidant activity as well as cytotoxicity against HeLa cervical cancer cell line. The present study demonstrated the potential use of the marine actinobacterial strain of Nocardiopsis sp. MBRC-48 as an important source for gold nanoparticles with improved biomedical applications including antimicrobial, antioxidant as well as cytotoxic agent.     

Swellable Ciprofloxacin-Loaded Nano-in-Micro Hydrogel Particles for Local Lung Drug Delivery

Incorporation of drug-loaded nanoparticles into swellable and respirable microparticles is a promising strategy to avoid rapid clearance from the lung and achieve sustained drug release. In this investigation, a copolymer of polyethylene glycol grafted onto phthaloyl chitosan (PEG-g-PHCs) was synthesized and then self-assembled with ciprofloxacin to form drug-loaded nanoparticles. The nanoparticles and free drug were encapsulated into respirable and swellable alginate micro hydrogel particles and assessed as a novel system for sustained pulmonary drug delivery. Particle size, morphology, dynamic swelling profile, and in vitro drug release were investigated. Results showed that drug-loaded nanoparticles with size of 218 nm were entrapped into 3.9-μm micro hydrogel particles. The dry nano-in-micro hydrogel particles exhibited a rapid initial swelling within 2 min and showed sustained drug release. Preliminary in vivo pharmacokinetic studies were performed with formulations delivered to rats by intratracheal insufflation. Ciprofloxacin concentrations in plasma and in lung tissue and lavage were measured up to 7 h. The swellable particles showed lower ciprofloxacin levels in plasma than the controlled group (a mixture of lactose with micronized ciprofloxacin), while swellable particles achieved higher concentrations in lung tissue and lavage, indicating the swellable particles could be used for controlling drug release and prolonging lung drug concentrations.KEY WORDS: alveolar macrophage, antibiotics, cross-linking, hydrogel swelling, intratracheal insufflation