Colloidal nanocarriers: a review on formulation technology, types and applications toward targeted drug delivery

Colloidal nanocarriers, in their various forms, have the possibility of providing endless opportunities in the area of drug delivery. The current communication embodies an in-depth discussion of colloidal nanocarriers with respect to formulation aspects, types, and site-specific drug targeting using various forms of colloidal nanocarriers with special insights to the field of oncology. Specialized nanotechnological approaches like quantum dots, dendrimers, integrins, monoclonal antibodies, and so forth, which have been extensively researched for targeted delivery of therapeutic and diagnostic agents, are also discussed. Nanotechnological patents, issued by the U.S. Patent and Trademark Office in the area of drug delivery, are also included in this review to emphasize the importance of nanotechnology in the current research scenario.

FROM THE CLINICAL EDITOR

Colloidal nanocarriers provide almost endless opportunities in the area of drug delivery. While the review mainly addresses potential oncological applications, similar approaches may be applicable in other conditions with a requirement for targeted drug delivery. Technologies including quantum dots, dendrimers, integrins, monoclonal antibodies are discussed, along with US-based patents related to these methods.

Automated high resolution optical mapping using arrayed, fluid-fixed DNA molecules

New mapping approaches construct ordered restriction maps from fluorescence microscope images of individual, endonuclease-digested DNA molecules. In optical mapping, molecules are elongated and fixed onto derivatized glass surfaces, preserving biochemical accessibility and fragment order after enzymatic digestion. Measurements of relative fluorescence intensity and apparent length determine the sizes of restriction fragments, enabling ordered map construction without electrophoretic analysis. The optical mapping system reported here is based on our physical characterization of an effect using fluid flows developed within tiny, evaporating droplets to elongate and fix DNA molecules onto derivatized surfaces. Such evaporation-driven molecular fixation produces well elongated molecules accessible to restriction endonucleases, and notably, DNA polymerase I. We then developed the robotic means to grid DNA spots in well defined arrays that are digested and analyzed in parallel. To effectively harness this effect for high-throughput genome mapping, we developed: (i) machine vision and automatic image acquisition techniques to work with fixed, digested molecules within gridded samples, and (ii) Bayesian inference approaches that are used to analyze machine vision data, automatically producing high-resolution restriction maps from images of individual DNA molecules. The aggregate significance of this work is the development of an integrated system for mapping small insert clones allowing biochemical data obtained from engineered ensembles of individual molecules to be automatically accumulated and analyzed for map construction. These approaches are sufficiently general for varied biochemical analyses of individual molecules using statistically meaningful population sizes.

Concentration dependent antioxidant/pro-oxidant activity of curcumin studies from AAPH induced hemolysis of RBCs

The antioxidant properties of curcumin have been studied by evaluating its ability to protect RBCs from AAPH (2,2'-azobis (2-amidinopropane) hydrochloride) induced oxidative damage. RBCs are susceptible to oxidative damage, resulting in peroxidation of the membrane lipids, release of hemoglobin (hemolysis), release of intracellular K(+) ions and depletion of glutathione (GSH). In this paper, lipid peroxidation, hemolysis and K(+) ion loss in RBCs were assessed respectively by formation of thiobarbituric acid reactive substances (TBARS), absorbance of hemoglobin at 532nm and flame photometry. The treatment of RBCs with curcumin showed concentration dependant decrease in level of TBARS and hemolysis. The IC(50) values for inhibition of lipid peroxidation and hemolysis were estimated to be 23.2+/-2.5 and 43+/-5microM respectively. However in contrast to the above mentioned effects, curcumin in similar concentration range, did not prevent release of intracellular K(+) ions during the process of hemolysis, rather curcumin induced its release even in the absence of hemolysis. The ability of curcumin to prevent oxidation of intracellular GSH due to hemolysis showed mixed results. At low concentrations of curcumin (<10microM) it prevented GSH depletion and at higher concentrations, the GSH levels decreased gradually. Curcumin scavenges the peroxyl radical generated from AAPH. Based on these results, it is concluded that curcumin exhibits both antioxidant/pro-oxidant activity, in a concentration dependent manner.

Whole-genome shotgun optical mapping of Deinococcus radiodurans

A whole-genome restriction map of Deinococcus radiodurans, a radiation-resistant bacterium able to survive up to 15,000 grays of ionizing radiation, was constructed without using DNA libraries, the polymerase chain reaction, or electrophoresis. Very large, randomly sheared, genomic DNA fragments were used to construct maps from individual DNA molecules that were assembled into two circular overlapping maps (2.6 and 0.415 megabases), without gaps. A third smaller chromosome (176 kilobases) was identified and characterized. Aberrant nonlinear DNA structures that may define chromosome structure and organization, as well as intermediates in DNA repair, were directly visualized by optical mapping techniques after gamma irradiation.

Disruption of transforming growth factor-beta signaling through beta-spectrin ELF leads to hepatocellular cancer through cyclin D1 activation

Transforming growth factor-beta (TGF-beta) signaling members, TGF-beta receptor type II (TBRII), Smad2, Smad4 and Smad adaptor, embryonic liver fodrin (ELF), are prominent tumor suppressors in gastrointestinal cancers. Here, we show that 40% of elf(+/-) mice spontaneously develop hepatocellular cancer (HCC) with markedly increased cyclin D1, cyclin-dependent kinase 4 (Cdk4), c-Myc and MDM2 expression. Reduced ELF but not TBRII, or Smad4 was observed in 8 of 9 human HCCs (P<0.017). ELF and TBRII are also markedly decreased in human HCC cell lines SNU-398 and SNU-475. Restoration of ELF and TBRII in SNU-398 cells markedly decreases cyclin D1 as well as hyperphosphorylated-retinoblastoma (hyperphosphorylated-pRb). Thus, we show that TGF-beta signaling and Smad adaptor ELF suppress human hepatocarcinogenesis, potentially through cyclin D1 deregulation. Loss of ELF could serve as a primary event in progression toward a fully transformed phenotype and could hold promise for new therapeutic approaches in human HCCs.

Osmotically controlled oral drug delivery

It is advantageous to deliver some drugs with short half-life, and which are to be given frequently for chronic ailments, in the form of controlled-release (CR) formulations. The orally administered drugs, in the form of conventional matrix or reservoir type formulations, pose problems of bioavailability fluctuations due to gastric pH variations. Moreover, the release of drug(s) from these systems is affected by the hydrodynamic conditions of the body. Osmotically controlled drug delivery systems utilize the principles of osmotic pressure for the controlled delivery of active agent(s). The release rate of drug(s) from these systems is independent of the physiological factors of the gastrointestinal (GI) tract to a large extent. In the present review, theory underlying the delivery of drugs from osmotic systems is presented. Different types of oral osmotic systems, their advantages over conventional matrix and reservoir types of systems, and their applications are also discussed. Finally, some of the limitations, adverse effects, and patent and market status of these systems are reviewed. These systems form a major segment of drug delivery products. Because of their advantages and strong market potential, it appears that the future of osmotic systems in rate-controlled oral drug delivery is promising.

Development and evaluation of a novel floating in situ gelling system of amoxicillin for eradication of Helicobacter pylori

The aim of this study was to develop a new intra-gastric floating in situ gelling system for controlled delivery of amoxicillin for the treatment of peptic ulcer disease caused by Helicobacter pylori (H. pylori). Gellan based amoxicillin floating in situ gelling systems (AFIG) were prepared by dissolving varying concentrations of gellan gum in deionized water containing sodium citrate, to which varying concentrations of drug and calcium carbonate, as gas-forming agent, was added and dissolved by stirring. The formulation variables like concentration of gellan gum and calcium carbonate significantly affected the in vitro drug release from the prepared AFIG. The in vivo H. pylori clearance efficacy of prepared AFIG in reference to amoxicillin suspension following repeated oral administration to H. pylori infected Mongolian gerbils was examined by polymerase chain reaction (PCR) technique and by a microbial culture method. AFIG showed a significant anti-H. pylori effect in the in vivo gerbil model. It was noted that the required amount of amoxicillin for eradication of H. pylori was 10 times less in AFIG than from the corresponding amoxicillin suspension. The results further substantiated that the prepared AFIG has feasibility of forming rigid gels in the gastric environment and eradicated H. pylori from the gastrointestinal tract more effectively than amoxicillin suspension because of the prolonged gastrointestinal residence time of the formulation.

In vitro antioxidant studies and free radical reactions of triphala, an ayurvedic formulation and its constituents

The aqueous extract of the fruits of Emblica officinalis (T1), Terminalia chebula (T2) and Terminalia belerica (T3) and their equiproportional mixture triphala were evaluated for their in vitro antioxidant activity. gamma-Radiation induced strand break formation in plasmid DNA (pBR322) was effectively inhibited by triphala and its constituents in the concentration range 25-200 microg/mL with a percentage inhibition of T1 (30%-83%), T2 (21%-71%), T3 (8%-58%) and triphala (17%-63%). They also inhibited radiation induced lipid peroxidation in rat liver microsomes effectively with IC(50) values less than 15 microg/mL. The extracts were found to possess the ability to scavenge free radicals such as DPPH and superoxide. As the phenolic compounds present in these extracts are mostly responsible for their radical scavenging activity, the total phenolic contents present in these extracts were determined and expressed in terms of gallic acid equivalents and were found to vary from 33% to 44%. These studies revealed that all three constituents of triphala are active and they exhibit slightly different activities under different conditions. T1 shows greater efficiency in lipid peroxidation and plasmid DNA assay, while T2 has greater radical scavenging activity. Thus their mixture, triphala, is expected to be more efficient due to the combined activity of the individual components.

Trends in maternal mortality in India over two decades in nationally representative surveys

OBJECTIVE

To assess national and regional trends and causes-specific distribution of maternal mortality in India.

DESIGN

Nationally representative cross-sectional surveys.

SETTING

All of India from 1997 to 2020.

SAMPLE

About 10 000 maternal deaths among 4.3 million live births over two decades.

METHODS

We analysed trends in the maternal mortality ratio (MMR) from 1997 through 2020, estimated absolute maternal deaths and examined the causes of maternal death using nationally representative data sources. We partitioned female deaths (aged 15-49 years) and live birth totals, based on the 2001-2014 Million Death Study to United Nations (UN) demographic totals for the country.

MAIN OUTCOME MEASURES

Maternal mortality burden and distribution of causes.

RESULTS

The MMR declined in India by about 70% from 398/100 000 live births (95% CI 378-417) in 1997-98 to 99/100 000 (90-108) in 2020. About 1.30 million (95% CI 1.26-1.35 million) maternal deaths occurred between 1997 and 2020, with about 23 800 (95% CI 21 700-26 000) in 2020, with most occurring in poorer states (63%) and among women aged 20-29 years (58%). The MMRs for Assam (215), Uttar Pradesh/Uttarakhand (192) and Madhya Pradesh/Chhattisgarh (170) were highest, surpassing India's 2016-2018 estimate of 113 (95% CI 103-123). After adjustment for education and other variables, the risks of maternal death were highest in rural and tribal areas of north-eastern and northern states. The leading causes of maternal death were obstetric haemorrhage (47%; higher in poorer states), pregnancy-related infection (12%) and hypertensive disorders of pregnancy (7%).

CONCLUSIONS

India could achieve the UN 2030 MMR goals if the average rate of reduction is maintained. However, without further intervention, the poorer states will not.

TWEETABLE ABSTRACT

We estimated that 1.3 million Indian women died from maternal causes over the last two decades. Although maternal mortality rates have fallen by 70% overall, the poorer states lag behind.

Detecting gene copy number fluctuations in tumor cells by microarray analysis of genomic representations

In this work, we explore the use of representations in conjunction with DNA microarray technology to measure gene copy number changes in cancer. We demonstrate that arrays of DNA probes derived from low-complexity representations can be used to detect amplifications, deletions, and polymorphic differences when hybridized to representations of genomic DNA. The method is both reproducible and verifiable, and is applicable even to microscopic amounts of primary tumors. We also present a mathematical model for array performance that is useful for designing and understanding DNA microarray hybridization protocols. The future applications and challenges of this approach are discussed.

Shotgun optical maps of the whole Escherichia coli O157:H7 genome

We have constructed NheI and XhoI optical maps of Escherichia coli O157:H7 solely from genomic DNA molecules to provide a uniquely valuable scaffold for contig closure and sequence validation. E. coli O157:H7 is a common pathogen found in contaminated food and water. Our approach obviated the need for the analysis of clones, PCR products, and hybridizations, because maps were constructed from ensembles of single DNA molecules. Shotgun sequencing of bacterial genomes remains labor-intensive, despite advances in sequencing technology. This is partly due to manual intervention required during the last stages of finishing. The applicability of optical mapping to this problem was enhanced by advances in machine vision techniques that improved mapping throughput and created a path to full automation of mapping. Comparisons were made between maps and sequence data that characterized sequence gaps and guided nascent assemblies.

Optical mapping and its potential for large-scale sequencing projects

Physical mapping has been rediscovered as an important component of large-scale sequencing projects. Restriction maps provide landmark sequences at defined intervals, and high-resolution restriction maps can be assembled from ensembles of single molecules by optical means. Such optical maps can be constructed from both large-insert clones and genomic DNA, and are used as a scaffold for accurately aligning sequence contigs generated by shotgun sequencing.

A shotgun optical map of the entire Plasmodium falciparum genome

The unicellular parasite Plasmodium falciparum is the cause of human malaria, resulting in 1.7-2.5 million deaths each year. To develop new means to treat or prevent malaria, the Malaria Genome Consortium was formed to sequence and annotate the entire 24.6-Mb genome. The plan, already underway, is to sequence libraries created from chromosomal DNA separated by pulsed-field gel electrophoresis (PFGE). The AT-rich genome of P. falciparum presents problems in terms of reliable library construction and the relative paucity of dense physical markers or extensive genetic resources. To deal with these problems, we reasoned that a high-resolution, ordered restriction map covering the entire genome could serve as a scaffold for the alignment and verification of sequence contigs developed by members of the consortium. Thus optical mapping was advanced to use simply extracted, unfractionated genomic DNA as its principal substrate. Ordered restriction maps (BamHI and NheI) derived from single molecules were assembled into 14 deep contigs corresponding to the molecular karyotype determined by PFGE (ref. 3).

Design, development, and biopharmaceutical properties of buccoadhesive compacts of pentazocine

Buccoadhesive compacts (BCs) of pentazocine (PZ) were prepared by the direct compression method using polymers like carbopol 974P (CP 974P) and hydroxypropyl methylcellulose (HPMC K4M) in ratios of 1:0 (batch B1), 1:1 (B2), 1:2 (B3), 1:4 (B4), and 0:1 (B5). The compacts were evaluated for thickness uniformity, weight variation, drug content uniformity, and swelling index. Swelling was increased with an increase in HPMC K4M content in the compacts. An in vitro assembly was developed to measure and compare the bioadhesive strength of compacts. The maximum bioadhesive strength was observed in compacts formulated with a combination of CP 974P and HPMC K4M. The compacts were evaluated in vitro for 24 hr in pH 6.6 phosphate buffer using a standardized dissolution apparatus. The data were evaluated by a simple power equation (Mt/M infinity = Ktn); it was observed that all the compacts followed non-Fickian release kinetics. Some of the buccoadhesive compacts were evaluated in vivo in rabbits. The compacts gave controlled blood level profiles with a twofold to threefold increase in area-under-the-curve (AUC) values in comparison to oral administration of aqueous drug solution.

Reactions of Biological Oxidants with Selenourea: Formation of Redox Active Nanoselenium

Reactions of biological oxidizing agents, such as hydroxyl radicals ((*)OH), singlet oxygen ((1)O(2)), hydrogen peroxide (H(2)O(2)), and peroxynitrite (ONOO(-)) with selenourea were studied. The kinetics of the reactions was followed using time-resolved techniques, and the bimolecular rate constants were determined. In all these reactions, under aerated conditions, elemental red selenium was produced as one of the reaction products. The average size of the selenium particles could be controlled and stabilized in the range of 20-100 nm with the addition of bovine serum albumin (BSA) or sodium dodecyl sulfate (SDS). The particles were characterized by dynamic light scattering studies (DLS), which revealed that the size and distribution of the particles depended mainly on the amount of selenourea undergoing oxidation. Other factors such as the nature of the oxidant and the concentration of the stabilizer also are important in stabilizing the particles. Nanoselenium-reduced ABTS(*-) to colorless ABTS(2-) (ABTS = 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) and oxidized dichlorodihydrofluoresecein diacetate (DCFA) to fluorescent dichlorofluorescein (DCF) indicating its ability to participate in redox and free radical reactions. The reactivity of selenium nanoparticles with these systems varied linearly with the surface area of the particles. The studies demonstrate that selenourea undergoes oxidation with both one-electron and two-electron oxidants to produce elemental selenium, which, on stabilization to nanometer size, exhibits size-dependent redox activity.

Elf3 encodes a novel 200-kD beta-spectrin: role in liver development

beta-spectrins are crucial for the maintenance of cell shape, the establishment of cell polarity, and the formation of distinct membrane domains. Our strategy for identifying genes important for hepatocyte polarity has been to utilize subtractive hybridization of early embryonic mouse cDNA liver libraries. As a result, we have cloned three isoforms of a novel beta-spectrin elf (embryonic liver beta-fodrin), and here we report the analysis of elf3, the longest isoform (8172 nt). ELF3 comprises 2154 residues with an overall similarity of 89.0% and 95.3% to mouse beta-spectrin (betaSpIIsigma1) at the nucleotide and amino acid level, respectively. ELF3 is characterized by an actin-binding domain, a long repeat domain, and a short regulatory domain remarkable for the absence of a PH domain. Linkage analysis reveals that elf3 maps to mouse chromosome 11 between D11Bir6 and D11Xrf477, a different chromosomal locus from that of the other four spectrin genes. Northern blot analysis utilizing an elf3 3'-UTR probe demonstrates an abundant 9.0-kb transcript in brain, liver, and heart tissues. Western blot with a polyclonal antibody against ELF identifies a 200 kD protein in mouse liver, brain, kidney, and heart tissues. Immunohistochemical studies demonstrate ELF labeling of the basolateral or sinusoidal membranes surface as well as a granular cytoplasmic pattern in hepatocytes. Antisense studies utilizing cultured liver explants show a vital role of elf3 in hepatocyte differentiation and intrahepatic bile duct formation. The differential expression, tissue localization, and functional studies demonstrate the importance of elf3 in modulating interactions between various components of the cytoskeleton proteins controlling liver and bile duct development.

Sodium alginate microspheres of metoprolol tartrate for intranasal systemic delivery: development and evaluation

Bioadhesive sodium alginate microspheres of Metoprolol tartrate (MT) for intranasal systemic delivery were prepared to avoid the first-pass effect, as an alternative therapy to injection, and to obtain improved therapeutic efficacy in the treatment of hypertension and angina pectoris. The microspheres (Ms) were prepared using emulsification--cross-linking method. The formulation variables were drug loading, polymer concentration, cross-linking agent concentration, and cross-linking time. The Ms were evaluated for characteristics, like particle size, incorporation efficiency, swelling ability, in vitro bioadhesion, in vitro drug release, and in vivo pharmacodynamic performance in rabbits against isoprenaline-induced tachycardia. Treatment of in vitro data to different kinetic equations indicated matrix-diffusion controlled drug delivery from sodium alginate Ms. Polymer concentration, cross-linking agent concentration, and cross-linking time influenced the drug release profiles significantly. In vivo studies indicated significantly improved therapeutic efficacy of MT from Ms with sustained and controlled inhibition of isoprenaline-induced tachycardia as compared with oral and nasal administration of drug solution.

Genomics via optical mapping. II: Ordered restriction maps

In this paper, we describe our algorithmic approach to constructing ordered restriction maps based on the data created from the images of population of individual DNA molecules (clones) digested by restriction enzymes. The goal is to devise map-making algorithms capable of producing high-resolution, high-accuracy maps rapidly and in a scalable manner. The resulting software is a key component of our optical mapping automation tools and has been used routinely to map cosmid, lambda and BAC clones. The experimental results appear highly promising.

High-resolution restriction maps of bacterial artificial chromosomes constructed by optical mapping

Large insert clone libraries have been the primary resource used for the physical mapping of the human genome. Research directions in the genome community now are shifting direction from purely mapping to large-scale sequencing, which in turn, require new standards to be met by physical maps and large insert libraries. Bacterial artificial chromosome libraries offer enormous potential as the chosen substrate for both mapping and sequencing studies. Physical mapping, however, has come under some scrutiny as being "redundant" in the age of large-scale automated sequencing. We report the development and applications of nonelectrophoretic, optical approaches for high-resolution mapping of bacterial artificial chromosome that offer the potential to complement and thereby advance large-scale sequencing projects.

Ficus racemosa Stem Bark Extract: A Potent Antioxidant and a Probable Natural Radioprotector

Ethanol extract (FRE) and water extract (FRW) of Ficus racemosa (family: Moraceae) were subjected to free radical scavenging both by steady state and time resolved methods such as nanosecond pulse radiolysis and stopped-flow spectrophotometric analyses. FRE exhibited significantly higher steady state antioxidant activity than FRW. FRE exhibited concentration dependent DPPH, ABTS^•−, hydroxyl radical and superoxide radical scavenging and inhibition of lipid peroxidation with IC₅₀ comparable with tested standard compounds. In vitro radioprotective potential of FRE was studied using micronucleus assay in irradiated Chinese hamster lung fibroblast cells (V79). Pretreatment with different doses of FRE 1h prior to 2 Gy γ-radiation resulted in a significant (P < 0.001) decrease in the percentage of micronucleated binuclear V79 cells. Maximum radioprotection was observed at 20 μg/ml of FRE. The radioprotection was found to be significant (P < 0.01) when cells were treated with optimum dose of FRE (20 μg/ml) 1 h prior to 0.5, 1, 2, 3 and 4 Gy γ-irradiation compared to the respective radiation controls. The cytokinesis-block proliferative index indicated that FRE does not alter radiation induced cell cycle delay. Based on all these results we conclude that the ethanol extract of F. racemosa acts as a potent antioxidant and a probable radioprotector.

Colon targeted drug delivery systems--an overview

In the last two decades colon targeted drug delivery has gained increased importance not just for the deliver drugs for the treatment of various colonic diseases but also for its potential for delivery of proteins and therapeutic peptides. In the past various traditional approaches used for colon targeted delivery like prodrugs, pH, time dependent, and microflora activated systems, have achieved limited success. For successful colon targeted drug delivery, the drug needs to be protected from absorption and/or the environment of the upper gastrointestinal tract and then be abruptly released into the colon. Hence continuous efforts have been made on designing colon targeted drug delivery systems with improved site specificity and versatile drug release kinetics to fulfill different therapeutic needs. In last couple of years few new systems have been developed for colon targeted drug delivery such as pressure dependent systems, CODES technology, microsponges, pectin and galactomannan coating, microbially triggered osmotic systems, lectins and neoglyconjugated etc. which are reported to have better in-vivo site specificity and design rationale than the earlier approaches. This review article gives an overview of various approaches for colonic targeted drug delivery with emphasis on newer systems, their merits and demerits, in vitro/ in-vivo evaluation and market status of such delivery systems.

Itih-4, a serine protease inhibitor regulated in interleukin-6-dependent liver formation: role in liver development and regeneration

Inter-alpha-trypsin inhibitor-4 (Itih-4) is a liver-restricted member of the serine protease inhibitor family with diverse functions as an anti-apoptotic and matrix stabilizing molecule that are important throughout development. We investigate the functional role of Itih-4 in liver formation, regeneration (LR) and examine its role in calcium and hyaluronic acid binding. Itih-4 expression is prominent in early liver development at E9 and later at E16, being restricted to hepatoblasts, immature hepatocytes, and differentiated hepatocytes. We note a marked and differential increase in Itih-4 labeling in proliferating hepatocytes, compared with bile duct cells in liver explant cultures treated with interleukin-6 (IL-6). After partial hepatectomy, maximal Itih-4 expression occurs in a bimodal manner at 30 min and at 12 hr, with a predominant centrizonal distribution. There is no detectable binding of glutathione transferase-fusion Itih-4 protein to calcium and hyaluronic acid, indicating a possible requirement for posttranslational modifications for these functions. These results suggest that in LR, Itih-4 expression corresponds to that of immediate early genes and may contribute to the entry of normally quiescent hepatocytes into the early stages of the cell cycle. The markedly high expression of Itih-4 in early liver development and in explants treated with IL-6 suggests a prominent role for Itih-4 at key points in liver formation.