Stability and antimicrobial effect of amikacin-loaded solid lipid nanoparticles

Assessing gut barrier integrity and reproductive performance following pre-mating oral administration of solid-lipid-nanoparticles designed for drug delivery

Solid lipid nanoparticles (SLNs) have gained interest as drug delivery carriers due to their efficient cellular internalization and increased therapeutic effect of the loaded drug, with minimal side effects. Although recently several studies have shown the possibility to administer SLNs during pregnancy to vehicle mRNA to the placenta, data about the effect of premating exposure to SLNs on pregnancy outcome are scant. Considering that assumption of drug-delivering nanocarriers in reproductive age may potentially affect women's reproductive health, the aim of the present study was to evaluate whether repeated oral administration of SLNs to female mice prior to mating would influence key pregnancy outcomes. For this purpose, SLNs melatonin loaded (SLN + mlt) or unloaded were orally administered to CD1 female mice at two different dosages-low (7.5 mg/kg) and high (750 mg/kg) -three times a week for 6 weeks. Females mice were mated and pregnancy was monitored from conception to delivery. All the assessed pregnancy parameters, including time to pregnancy, pregnancy duration, litter size, and the presence of any gross anomalies in the pups, and maternal key biochemical parameters were not significantly affected by SLN administration. Embryonic development was also evaluated and no effects on the number of implantation sites, fetus numbers, incidence of fetal resorptions, and measurements of crown-rump length, as well as fetal and placental weights, were observed in the treated mothers. The impact of SLNs on maternal intestinal barrier integrity and inflammation was assessed both in vivo in mice and in vitro using an intestinal epithelial barrier model by qRT-PCR. Results showed that unloaded SLNs, but not the SLN + mlt, affected intestinal barrier integrity. Although variation in the expression of inflammatory cytokines was recorded, this did not reflect in significant histological alterations and the integrity of the intestinal barrier was maintained. The in vitro model further confirmed the biocompatibility of SLNs, showing that both loaded and unloaded SLNs did not affect the integrity of the simulated intestinal epithelial barrier. In conclusion, these data suggest that administering SLNs, as a drug delivery vehicle, prior to conception does not affect either maternal health or fetal development, posing no risk to future pregnancy.

The effect of clinically relevant beta-lactam, aminoglycoside, and quinolone antibiotics on bacterial extracellular vesicle release from E. coli

Sepsis, a leading cause of death in hospitals, can be defined as a dysregulated host inflammatory response to infection, which can lead to tissue damage, organ failure, and cardiovascular complications. Although there is no cure for sepsis, the condition is typically managed with broad spectrum antibiotics to eliminate any potential bacterial source of infection. However, a potential side-effect of antibiotic treatment is the enhanced release of bacterial extracellular vesicles (BEVs). BEVs are membrane-bound nanoparticles produced by a variety of mechanisms, one of which includes the pinching-off of the outer membrane (in Gram-negative bacteria) to enclose proteins and other biological molecules for transport and intercellular communication. Some of the Gram-negative EV cargo, including Peptidoglycan associated lipoprotein (Pal) and Outer membrane protein A (OmpA), have been shown to induce both acute and chronic inflammation in host tissue. We hypothesize that antibiotic concentration and its mechanism of action can have an effect on the amount of released BEVs, which could potentially exacerbate the host inflammatory response. In this study, we evaluated nine clinically relevant antibiotics for their effect on EV release from Escherichia coli. EVs were characterized using immunoblotting, nanoparticle tracking analysis, and transmission electron microscopy. Several beta-lactam antibiotics caused significantly more EV release, while quinolone and aminoglycosides caused relatively less vesiculation. Further study is warranted to corroborate the correlation between an antibiotic's mechanism of action and its effect on EV release, but these results underline the importance of antibiotic choice when treating sepsis patients.

Overcoming Multidrug Resistance of Antibiotics via Nanodelivery Systems

Antibiotic resistance has become a threat to microbial therapies nowadays. The conventional approaches possess several limitations to combat microbial infections. Therefore, to overcome such complications, novel drug delivery systems have gained pharmaceutical scientists’ interest. Significant findings have validated the effectiveness of novel drug delivery systems such as polymeric nanoparticles, liposomes, metallic nanoparticles, dendrimers, and lipid-based nanoparticles against severe microbial infections and combating antimicrobial resistance. This review article comprises the specific mechanism of antibiotic resistance development in bacteria. In addition, the manuscript incorporated the advanced nanotechnological approaches with their mechanisms, including interaction with the bacterial cell wall, inhibition of biofilm formations, activation of innate and adaptive host immune response, generation of reactive oxygen species, and induction of intracellular effect to fight against antibiotic resistance. A section of this article demonstrated the findings related to the development of delivery systems. Lastly, the role of microfluidics in fighting antimicrobial resistance has been discussed. Overall, this review article is an amalgamation of various strategies to study the role of novel approaches and their mechanism to fight against the resistance developed to the antimicrobial therapies.

Perspectives and Prospective on Solid Lipid Nanoparticles as Drug Delivery Systems

Combating multiple drug resistance necessitates the delivery of drug molecules at the cellular level. Novel drug delivery formulations have made it possible to improve the therapeutic effects of drugs and have opened up new possibilities for research. Solid lipid nanoparticles (SLNs), a class of colloidal drug carriers made of lipids, have emerged as potentially effective drug delivery systems. The use of SLNs is associated with numerous advantages such as low toxicity, high bioavailability of drugs, versatility in the incorporation of hydrophilic and lipophilic drugs, and the potential for production of large quantities of the carrier systems. The SLNs and nanostructured lipid carriers (NLCs) are the two most frequently used types of nanoparticles. These types of nanoparticles can be adjusted to deliver medications in specific dosages to specific tissues, while minimizing leakage and binding to non-target tissues.

Systematic Development and Characterization of Novel, High Drug-Loaded, Photostable, Curcumin Solid Lipid Nanoparticle Hydrogel for Wound Healing

The study aims to develop high drug-loaded (about 15% lipid matrix) curcumin solid lipid nanoparticles (CSLNs) for wound healing. CSLNs prepared by hot, high-pressure homogenization, without using organic solvents, were optimized using the Taguchi design followed by the central composite design. The optimized CSLNs exhibited a high assay/drug content (0.6% w/w), solubility (6 × 105 times), and EE (75%) with a particle size < 200 nm (PDI-0.143). The CSLNs were safe (in vitro and in vivo), photostable, autoclavable, stable up to one year at 30 °C and under refrigeration and exhibited a controlled release (zero-order; 5 days). XRD, FTIR, and DSC confirmed solubilization and entrapment of the curcumin within the SLNs. TEM and FESEM revealed a smooth and spherical shape. The CSLNs showed a significant antimicrobial effect (MIC of 64 µg/mL for planktonic cells; 512 µg/mL for biofilm formation; and 2 mg/mL for mature biofilm) against Staphylococcus aureus 9144, while free curcumin dispersion did not exhibit any effect. This is the first report on the disruption of mature biofilms by curcumin solid lipid nanoparticles (CSLNs). The cell proliferation potential of CSLNs was also evaluated in vitro while the wound healing potential of CSLNs (incorporated in a hydrogel) was assessed in vivo. In (i) nitrogen mustard gas and (ii) a full-thickness excision wound model, CSLNs exhibited (a) significantly faster wound closure, (b) histologically and immunohistochemically better healing, (c) lower oxidative stress (LPO) and (d) inflammation (TNFα), and (e) increased angiogenesis (VEGF) and antioxidant enzymes, i.e., catalase and GSH levels. CSLNs thus offer a promising modern wound therapy especially for infected wounds, considering their effects in mature biofilm disruption.

Facile Preparation of Tilmicosin-Loaded Polymeric Nanoparticle with Controlled Properties and Functions

As one of the effective broad-spectrum antimicrobial and anti-inflammatory drugs, tilmicosin (TIM) is applied extensively in a wide range of veterinary treatments. However, the low bioavailability typically leads to overuse of TIM in practical applications, which can cause residual accumulation in the environment and contamination of foodstuffs. Here, we report a precipitation method that allows us to prepare TIM-loaded poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) nanoparticles. Specifically, TIM and biocompatible P(MMA-co-MAA) are dissolved in methanol and then water is introduced as an antisolvent, which triggers the co-precipitation and leads to well-controlled nanoparticles. Depending on the drug/polymer mass ratio and the total concentration of drug and polymer, the formed nanoparticles display a tunable radius from 27 to 80 nm with a narrow size distribution, a high drug loading content, and a controlled release of TIM. The encapsulation does not interrupt the antibacterial function of TIM while reducing its cytotoxicity enormously. Moreover, the formed nanoparticles could be dried to powder through freeze-drying, and the redispersion of the particles hardly disturbs the particle size, size distribution, and drug loading content. Our study developed a facile and robust precipitation method for the controlled construction of TIM-loaded polymeric nanoparticles with tunable properties and functions, as well as improved biocompatibility, which shall improve the bioavailability of TIM and enhance the practical applications.

Pseudomonas aeruginosa Biofilms

Pseudomonas aeruginosa is an opportunistic human pathogen causing devastating acute and chronic infections in individuals with compromised immune systems. Its highly notorious persistence in clinical settings is attributed to its ability to form antibiotic-resistant biofilms. Biofilm is an architecture built mostly by autogenic extracellular polymeric substances which function as a scaffold to encase the bacteria together on surfaces, and to protect them from environmental stresses, impedes phagocytosis and thereby conferring the capacity for colonization and long-term persistence. Here we review the current knowledge on P. aeruginosa biofilms, its development stages, and molecular mechanisms of invasion and persistence conferred by biofilms. Explosive cell lysis within bacterial biofilm to produce essential communal materials, and interspecies biofilms of P. aeruginosa and commensal Streptococcus which impedes P. aeruginosa virulence and possibly improves disease conditions will also be discussed. Recent research on diagnostics of P. aeruginosa infections will be investigated. Finally, therapeutic strategies for the treatment of P. aeruginosa biofilms along with their advantages and limitations will be compiled.

Nanomedicine Approaches for the Pulmonary Treatment of Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disease affecting today nearly 70,000 patients worldwide and characterized by a hypersecretion of thick mucus difficult to clear arising from the defective CFTR protein. The over-production of the mucus secreted in the lungs, along with its altered composition and consistency, results in airway obstruction that makes the lungs susceptible to recurrent and persistent bacterial infections and endobronchial chronic inflammation, which are considered the primary cause of bronchiectasis, respiratory failure, and consequent death of patients. Despite the difficulty of treating the continuous infections caused by pathogens in CF patients, various strategies focused on the symptomatic therapy have been developed during the last few decades, showing significant positive impact on prognosis. Moreover, nowadays, the discovery of CFTR modulators as well as the development of gene therapy have provided new opportunity to treat CF. However, the lack of effective methods for delivery and especially targeted delivery of therapeutics specifically to lung tissues and cells limits the efficiency of the treatments. Nanomedicine represents an extraordinary opportunity for the improvement of current therapies and for the development of innovative treatment options for CF previously considered hard or impossible to treat. Due to the peculiar environment in which the therapies have to operate characterized by several biological barriers (pulmonary tract, mucus, epithelia, bacterial biofilm) the use of nanotechnologies to improve and enhance drug delivery or gene therapies is an extremely promising way to be pursued. The aim of this review is to revise the currently used treatments and to outline the most recent progresses about the use of nanotechnology for the management of CF.

Novel Therapeutic Strategies Applied to Pseudomonas aeruginosa Infections in Cystic Fibrosis

Cystic fibrosis (CF) is one of the most prevalent genetic diseases and a total of 1700 different genetic mutations can cause this condition. Patients that suffer this disease have a thickening of the mucus, creating an environment that promotes bacterial infections. Pseudomonas aeruginosa is a ubiquitous bacterium, which is frequently found in the lungs of CF patients. P. aeruginosa is known for its high level of antibiotic resistance as well as its high rate of mutation that allows it to rapidly evolve and adapt to a multitude of conditions. When a CF lung is infected with P. aeruginosa, the decay of the patient is accelerated, but there is little that can be done apart from controlling the infection with antibiotics. Novel strategies to control P. aeruginosa infection are imperative, and nanotechnology provides novel approaches to drug delivery that are more efficient than classic antibiotic treatments. These drug delivery systems are offering new prospects, especially for these patients with special mucus conditions and bacterial characteristics that limit antibiotic use.

Chinese White Wax Solid Lipid Nanoparticles as a Novel Nanocarrier of Curcumin for Inhibiting the Formation of Staphylococcus aureus Biofilms

Chinese white wax solid lipid nanoparticles (cwSLNs) were prepared by high shear homogenization and ultrasound methods. Using an optimized formula, spherical cwSLNs with an average particle size of 401.9 ± 21.3 nm were obtained. The cwSLNs showed high entrapment efficiency, approximately 84.6%, for loading curcumin. The curcumin loaded cwSLNs (Cur-cwSLNs) exhibited sustained drug release properties. Notably, Cur-cwSLNs had a higher drug release rate at pH 4.5 than at pH 7.4, which suggested their applicability in an acidic environment. Cur-cwSLNs were able to inhibit the growth of Staphylococcus aureus and were more effective at reducing the biofilms produced by this bacterium compared to free curcumin. This study confirmed that cwSLNs may be novel carriers for increasing the bioavailability of curcumin with the potential to inhibit the formation of S. aureus biofilms.

Tri-mannose grafting of chitosan nanocarriers remodels the macrophage response to bacterial infection

Background

Infectious diseases are still a leading cause of death and, with the emergence of drug resistance, pose a great threat to human health. New drugs and strategies are thus urgently needed to improve treatment efficacy and limit drug-associated side effects. Nanotechnology-based drug delivery systems are promising approaches, offering hope in the fight against drug resistant bacteria. However, how nanocarriers influence the response of innate immune cells to bacterial infection is mostly unknown.

Results

Here, we used Mycobacterium tuberculosis as a model of bacterial infection to examine the impact of mannose functionalization of chitosan nanocarriers (CS-NCs) on the human macrophage response. Both ungrafted and grafted CS-NCs were similarly internalized by macrophages, via an actin cytoskeleton-dependent process. Although tri-mannose ligands did not modify the capacity of CS-NCs to escape lysosomal degradation, they profoundly remodeled the response of M. tuberculosis-infected macrophages. mRNA sequencing showed nearly 900 genes to be differentially expressed due to tri-mannose grafting. Unexpectedly, the set of modulated genes was enriched for pathways involved in cell metabolism, particularly oxidative phosphorylation and sugar metabolism.

Conclusions

The ability to modulate cell metabolism by grafting ligands at the surface of nanoparticles may thus be a promising strategy to reprogram immune cells and improve the efficacy of encapsulated drugs.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0439-x) contains supplementary material, which is available to authorized users.

Optimization and Designing of Amikacin-loaded Poly D, L-Lactide-co-glycolide Nanoparticles for Effective and Sustained Drug Delivery

Purpose:

Amikacin, a water-soluble aminoglycoside antibiotic used to treat gram-negative bacillary infections, is a Biopharmaceutics Classification System class III drug having poor permeability and short half-life. It is given parenterally, which limits its use in patients warranting “at-home care.” An oral drug delivery of amikacin is, therefore, imminent.

Aim:

This work focused on establishing poly d, l-lactide-co-glycolide (PLGA)-based nanoparticles of amikacin with consolidated pharmaceutical attributes capable of circumventing gastrointestinal tract membrane barriers and promoting oral administration of the drug. The partied attributes are suggestive of enhanced uptake of the drug via Peyer’s patches overlaying small intestine and support successful oral delivery.

Materials and Methods:

To have a robust delivery system, a statistical Box–Behnken experimental design was used and formulation parameters such as homogenization time, probe sonication time, and drug/polymer ratio of amikacin-loaded PLGA nanoparticles (A-NPs) for obtaining monodispersed nanoparticles of adequate size and high drug loading were optimized.

Results:

The model suggested to use the optimum homogenization time, probe sonication time, and drug/polymer ratio as 30 s, 120 s, and 1:10, respectively. Under these formulation conditions, the particle size was found to be 260.3 nm and the drug loading was 3.645%.

Conclusion:

Biodegradable PLGA nanoparticulate systems with high payload, optimum size, and low polydispersity index will ensure successful uptake and ultimately leading to better bioavailability. Hence, under the aforementioned optimized conditions, the A-NPs prepared had particle size of 260.3 nm, which is appreciable for its permeability across small intestine, and drug loading of 3.645%.

Antagonistic activities of some probiotic lactobacilli culture supernatant on Serratia marcescens swarming motility and antibiotic resistance

BACKGROUND AND OBJECTIVES

Serratia marcescens, a potentially pathogenic bacterium, benefits from its swarming motility and resistance to antibiotic as two important virulence factors. Inappropriate use of antibiotics often results in drug resistance phenomenon in bacterial population. Use of probiotic bacteria has been recommended as partial replacement. In this study, we investigated the effects of some lactobacilli culture supernatant on swarming, motility and antibiotic resistance of S. marcescens.

MATERIALS AND METHODS

Antimicrobial activity of lactobacilli supernatant and susceptibility testing carried out on S. marcescens isolates. Pretreatment effect of lactobacilli culture supernatant on antibiotic - resistance pattern in S. marcescens was determined by comparison of the MIC of bacteria before and after the treatment.

RESULTS

Our results showed that pretreatment with L. acidophilus ATCC 4356 supernatant can affect the resistance of Serratia strains against ceftriaxone, but it had no effect on the resistance to other antibiotics. Furthermore, culture supernatant of lactobacilli with concentrations greater than 2%, had an effect on the swarming ability of S. marcescens ATCC 13880 and inhibited it.

CONCLUSION

Probiotic bacteria and their metabolites have the ability to inhibit virulence factors such as antibiotic resistance and swarming motility and can be used as alternatives to antibiotics.

Preparation and Optimization of Meropenem-Loaded Solid Lipid Nanoparticles: In Vitro Evaluation and Molecular Modeling

Encapsulation of antibiotics into nanocarriers has the potential to overcome resistance and disadvantages associated with conventional dosage forms as well as increase half-life of an antibiotic. Encapsulation of meropenem (MRPN) into solid lipid nanoparticles (SLNs) remains unexplored among the limited work reported on nanoformulation incorporating MRPN. The study aimed to use an experimental design, to optimize MRPN-loaded SLNs, and to undertake in vitro and in silico evaluations. A Box-Behnken design (BBD) was used to optimize manufacturing conditions of glycerol monostearate (GMS) SLNs loaded with MRPN. The SLNs were prepared using hot homogenization and ultrasonication method. Optimized MRPN-SLNs showed particle size, zeta potential, and entrapment efficiency of 112.61 ± 0.66 nm, -20.43 ± 0.99 mV, and 89.94 ± 1.26%, respectively. The morphology of the SLNs revealed nearly spherical shaped particles. Differential scanning calorimetry and X-ray diffraction analysis showed that meropenem was present in amorphous form in the SLNs. Controlled in vitro MRPN release from SLNs was achieved and followed the Korsmeyer-Peppas model (R ² = 0.9679). Prolonged in vitro antibacterial activity against Escherichia coli was also observed. The molecular modeling showed that both hydrophobic interactions and hydrogen bonding led to a stable MRPN-GMS complex formation, which was confirmed by its low heat of formation (-5536.13 kcal/mol). This stable complex could have contributed to the controlled release of MRPN from the SLNs and subsequent sustained antibacterial activity.

Macromolecular Conjugate and Biological Carrier Approaches for the Targeted Delivery of Antibiotics

For the past few decades, the rapid rise of antibiotic multidrug-resistance has presented a palpable threat to human health worldwide. Meanwhile, the number of novel antibiotics released to the market has been steadily declining. Therefore, it is imperative that we utilize innovative approaches for the development of antimicrobial therapies. This article will explore alternative strategies, namely drug conjugates and biological carriers for the targeted delivery of antibiotics, which are often eclipsed by their nanomedicine-based counterparts. A variety of macromolecules have been investigated as conjugate carriers, but only those most widely studied in the field of infectious diseases (e.g., proteins, peptides, antibodies) will be discussed in detail. For the latter group, blood cells, especially erythrocytes, have been successfully tested as homing carriers of antimicrobial agents. Bacteriophages have also been studied as a candidate for similar functions. Once these alternative strategies receive the amount of research interest and resources that would more accurately reflect their latent applicability, they will inevitably prove valuable in the perennial fight against antibiotic resistance.

Free and Nanoencapsulated Tobramycin: Effects on Planktonic and Biofilm Forms of Pseudomonas

Cystic fibrosis (CF) is a genetic disorder in which frequent pulmonary infections develop secondarily. One of the major pulmonary pathogens colonizing the respiratory tract of CF patients and causing chronic airway infections is Pseudomonasaeruginosa. Although tobramycin was initially effective against P. aeruginosa, tobramycin-resistant strains have emerged. Among the strategies for overcoming resistance to tobramycin and other antibiotics is encapsulation of the drugs in nanoparticles. In this study, we explored the antimicrobial activity of nanoencapsulated tobramycin, both in solid lipid nanoparticles (SLN) and in nanostructured lipid carriers (NLC), against clinical isolates of P. aeruginosa obtained from CF patients. We also investigated the efficacy of these formulations in biofilm eradication. In both experiments, the activities of SLN and NLC were compared with that of free tobramycin. The susceptibility of planktonic bacteria was determined using the broth microdilution method and by plotting bacterial growth. The minimal biofilm eradication concentration (MBEC) was determined to assess the efficacy of the different tobramycin formulations against biofilms. The activity of tobramycin-loaded SLN was less than that of either tobramycin-loaded NLC or free tobramycin. The minimum inhibitory concentration (MIC) and MBEC of nanoencapsulated tobramycin were slightly lower (1–2 logs) than the corresponding values of the free drug when determined in tobramycin-susceptible isolates. However, in tobramycin-resistant strains, the MIC and MBEC did not differ between either encapsulated form and free tobramycin. Our results demonstrate the efficacy of nanoencapsulated formulations in killing susceptible P. aeruginosa from CF and from other patients.

Synergic Antibacterial Effect of Curcumin with Ampicillin; Free Drug Solutions in Comparison with SLN Dispersions

Purpose: This study was designed to investigate benefit of using nanotechnology on increasing of synergic antibacterial effect of natural and chemical antibacterial agents. Methods: At first the MIC and MBC of Curcumin and Ampicillin as selected antibacterial agents was determined, after that Solid Lipid Nanoparticles (SLNs) of each active ingredients as well as Curcumin-Ampicillin loaded SLNs were prepared using high pressure homogenization technique. Characterization of prepared SLNs was done, then MIC, MBC and contact killing time were investigated for Curcumin-Ampicillin loaded SLNs in comparison with free Curcumin and Ampicillin solutions as well as Ampicillin and Curcumin SLNs. Results: Based on results nanoparticles with the size of 150 nm show much more decreased MIC and MBC when Ampicillin and Curcumin were loaded together on SLNs than solutions in which free Ampicillin and Curcumin were mixed. Conclusion: It seems that using nanotechnology could cause decrease the dosage of antibiotics and risk of having antibiotic resistance bacteria strains.

Sustained release Curcumin loaded Solid Lipid Nanoparticles

PURPOSE

curcumin is poorly water soluble drug with low bioavailability. Use of lipid systems in lipophilic substances increases solubility and bioavailability of poorly soluble drugs. The aim of this study was to prepare curcumin loaded Solid Lipid Nanoparticles (SLNs) with high loading efficiency, small particle size and prolonged release profile with enhanced antibacterial efficacy.

METHODS

to synthesize stable SLNs, freeze- Drying was done using mannitol as cryoprotectant. Cholesterol was used as carrier because of good tolerability and biocompatibility. SLNs were prepared using high pressure homogenization method.

RESULTS

optimized SLNs had 112 and 163 nm particle size before and after freeze drying, respectively. The prepared SLNs had 71% loading efficiency. 90% of loaded curcumin was released after 48 hours. Morphologic study for formulation was done by taking SEM pictures of curcumin SLNs. RESULTS show the spherical shape of curcumin SLNs. DSC studies were performed to determine prolonged release mechanism. Antimicrobial studies were done to compare the antimicrobial efficacy of curcumin SLNs with free curcumin. DSC studies showed probability of formation of hydrogen bonds between cholesterol and curcumin which resulted in prolonged release of curcumin. Lipid structure of cholesterol could cause enhanced permeability in studied bacteria to increase antibacterial characteristics of curcumin.

CONCLUSION

the designed curcumin SLNs could be candidate for formulation of different dosage forms or cosmeceutical products.

Sustained release Curcumin loaded Solid Lipid Nanoparticles

PURPOSE

curcumin is poorly water soluble drug with low bioavailability. Use of lipid systems in lipophilic substances increases solubility and bioavailability of poorly soluble drugs. The aim of this study was to prepare curcumin loaded Solid Lipid Nanoparticles (SLNs) with high loading efficiency, small particle size and prolonged release profile with enhanced antibacterial efficacy.

METHODS

to synthesize stable SLNs, freeze- Drying was done using mannitol as cryoprotectant. Cholesterol was used as carrier because of good tolerability and biocompatibility. SLNs were prepared using high pressure homogenization method.

RESULTS

optimized SLNs had 112 and 163 nm particle size before and after freeze drying, respectively. The prepared SLNs had 71% loading efficiency. 90% of loaded curcumin was released after 48 hours. Morphologic study for formulation was done by taking SEM pictures of curcumin SLNs. RESULTS show the spherical shape of curcumin SLNs. DSC studies were performed to determine prolonged release mechanism. Antimicrobial studies were done to compare the antimicrobial efficacy of curcumin SLNs with free curcumin. DSC studies showed probability of formation of hydrogen bonds between cholesterol and curcumin which resulted in prolonged release of curcumin. Lipid structure of cholesterol could cause enhanced permeability in studied bacteria to increase antibacterial characteristics of curcumin.

CONCLUSION

the designed curcumin SLNs could be candidate for formulation of different dosage forms or cosmeceutical products.

Preparation and evaluation of tilmicosin-loaded hydrogenated castor oil nanoparticle suspensions of different particle sizes

Three tilmicosin-loaded hydrogenated castor oil nanoparticle (TMS-HCO-NP) suspensions of different particle sizes were prepared with different polyvinyl alcohol surfactant concentrations using a hot homogenization and ultrasonic technique. The in vitro release, in vitro antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability study were conducted to evaluate the characteristics of the suspensions. The in vitro tilmicosin release rate, antibacterial activity, mammalian cytotoxicity, acute toxicity in mice, and stability of the suspensions were evaluated. When prepared with polyvinyl alcohol concentrations of 0.2%, 1%, and 5%, the mean diameters of the nanoparticles in the three suspensions were 920±35 nm, 452±10 nm, and 151±4 nm, respectively. The three suspensions displayed biphasic release profiles similar to that of freeze-dried TMS-HCO-NP powders, with the exception of having a faster initial release. Moreover, suspensions of smaller-sized particles showed faster initial release, and lower minimum inhibitory concentrations and minimum bactericidal concentrations. Time-kill curves showed that within 12 hours, the suspension with the 151 nm particles had the most potent bactericidal activity, but later, the suspensions with larger-sized particles showed increased antibacterial activity. None of the three suspensions were cytotoxic at clinical dosage levels. At higher drug concentrations, all three suspensions showed similar concentration-dependent cytotoxicity. The suspension with the smallest-sized particle showed significantly more acute toxicity in mice, perhaps due to faster drug release. All three suspensions exhibited good stability at 4°C and at room temperature for at least 6 months. These results demonstrate that TMS-HCO-NP suspensions can be a promising formulation for tilmicosin, and that nanoparticle size can be an important consideration for formulation development.

Probiotic Properties of Lyophilized Cell Free Extract of Lactobacillus casei

BACKGROUND

In recent years there have been considerable interests in the use of probiotic live cells for nutritional and therapeutic purposes. This strategy can be concomitant with some limitations such as survival of live cell during the GI-transit and their effective delivery to target tissues upon ingestion. Several attempts have been made to overcome these limitations such as their microencapsulation, spray-drying and lyophilization.

OBJECTIVES

In this study extract of cultured probiotics without cells was evaluated for its antimicrobial effects, antioxidant activity, and its stability.

MATERIALS AND METHODS

In this work the potential of lyophilized-cell-free-probiotic-extract (LPE) as a suitable alternative strategy for the preparation of probiotic-products was investigated. The main aim of this study was to find out the antibacterial and antioxidant activity of LPE and also its stability. LPE was obtained by centrifugation and subsequent lyophilization of the collected supernatant from culture media of Lactobacillus casei. An enzymatic reagent-kit was used for detection of its content of lactic acid. Antibacterial test was performed using agar cup-plat-method, the DPPH scavenging -assay was used to determine its antioxidant activity and during a storage course, LPE was under a long-term stability study.

RESULTS

Results showed that, LPE had more antipathogenic effects, antioxidant activity, and stability during storage-time when compared to fresh probiotic-extract.

CONCLUSIONS

Employing the LPE as a new approach, gives novel concept of probiotic-products in food and medical marketing.