David Medina Cruz, PhD

Bimetallic nanoparticles, or BMNPs, are nanosized structures that are of growing interest in biomedical applications. Although their production shares aspects with physicochemical approaches for the synthesis of their monometallic counterparts, they can show a large variety of new properties and applications as a consequence of the synergetic effect between the two components. These applications can be as diverse as antibacterial treatments or anticancer or biological imaging approaches, as… Show more

Bimetallic nanoparticles, or BMNPs, are nanosized structures that are of growing interest in biomedical applications. Although their production shares aspects with physicochemical approaches for the synthesis of their monometallic counterparts, they can show a large variety of new properties and applications as a consequence of the synergetic effect between the two components. These applications can be as diverse as antibacterial treatments or anticancer or biological imaging approaches, as well as drug delivery. Nevertheless, utilization of BMNPs in such fields has received limited attention because of the severe lack of knowledge and concerns regarding the use of other nanomaterials, such as stability and biodegradability over time, tendency to form clusters, chemical reactivity, and biocompatibility. In this review, a close look at bimetallic systems is presented, focusing on their biomedical applications as antibacterial, anticancer, drug delivery, and imaging agents, showing significant enhancement of their features compared to their monometallic counterparts and other current used nanomaterials for biomedical applications. Show less

Tellurium (Te) is a brittle, mildly toxic, and rare metalloid with an extremely low abundance in the planet. The element has been used in both its bulk and nanoscale forms for several applications in solar cell industry, semiconductors, catalysis, or heavy metal removal, among others. The end of the last century witnessed an explosion in new strategies for synthesizing different Te nanostructures with controlled compositions, sizes, morphologies, and properties, which allow these structures to… Show more

Tellurium (Te) is a brittle, mildly toxic, and rare metalloid with an extremely low abundance in the planet. The element has been used in both its bulk and nanoscale forms for several applications in solar cell industry, semiconductors, catalysis, or heavy metal removal, among others. The end of the last century witnessed an explosion in new strategies for synthesizing different Te nanostructures with controlled compositions, sizes, morphologies, and properties, which allow these structures to enhance their impact in numerous applications. Nanomedicine has recently taken advantage of the metalloid in its nanoscale, showing promising applications as antibacterial, anticancer, and imaging agents. Nevertheless, the biological role of Te within living organisms remains mostly unknown, and just a few reports appear working on this matter. In this chapter, the forgotten elements are extensively studied in terms of its chemical, physical, and geological properties, and its main applications are summarized and studied for both bulk and nanosized tellurium. At the end, tellurium’s most important biomedical applications are presented with the aim to establish a general concept of the metalloid as a powerful biomedical tool with a bright future yet to be discovered. Show less

Current treatments for osteogenic disorders are often successful, however they are not free of drawbacks, such as toxicity or side effects. Nanotechnology offers a platform for drug delivery in the treatment of bone disorders, which can overcome such limitations. Nevertheless, traditional synthesis of nanomaterials presents environmental and health concerns due to its production of toxic by-products, the need for extreme and harsh raw materials, and their lack of biocompatibility over… Show more

Current treatments for osteogenic disorders are often successful, however they are not free of drawbacks, such as toxicity or side effects. Nanotechnology offers a platform for drug delivery in the treatment of bone disorders, which can overcome such limitations. Nevertheless, traditional synthesis of nanomaterials presents environmental and health concerns due to its production of toxic by-products, the need for extreme and harsh raw materials, and their lack of biocompatibility over time.

This review article contains an overview of the current status of treating osteogenic disorders employing green nanotechnological approaches, showing some of the latest advances in the application of green nanomaterials, as drug delivery carriers, for the effective treatment of osteogenic disorders.

Green nanotechnology, as a potential solution, is understood as the use of living organisms, biomolecules and environmentally friendly processes for the production of nanomaterials. Nanomaterials derived from bacterial cultures or biomolecules isolated from living organisms, such as carbohydrates, proteins, and nucleic acids, have been proven to be effective composites. These nanomaterials introduce enhancements in the treatment and prevention of osteogenic disorders, compared to physiochemically-synthesized nanostructures, specifically in terms of their improved cell attachment and proliferation, as well as their ability to prevent bacterial adhesion. Show less

Currently, antibiotic resistance and cancer are two of the most important public health problems killing more than ∼1.5 million people annually, showing that antibiotics and current chemotherapeutics are not as effective as they were in the past. Nanotechnology is presented here as a potential solution. However, current protocols for the traditional physicochemical synthesis of nanomaterials are not free of environmental and social drawbacks, often involving the use of toxic catalysts. This… Show more

Currently, antibiotic resistance and cancer are two of the most important public health problems killing more than ∼1.5 million people annually, showing that antibiotics and current chemotherapeutics are not as effective as they were in the past. Nanotechnology is presented here as a potential solution. However, current protocols for the traditional physicochemical synthesis of nanomaterials are not free of environmental and social drawbacks, often involving the use of toxic catalysts. This article shows the production of pure naked selenium nanoparticles (SeNPs) by a novel green process called pulsed laser ablation in liquids (PLAL). After the first set of irradiations, another set was performed to reduce the size below 100 nm, which resulted in a colloidal solution of spherical SeNPs with two main populations having sizes around ∼80 and ∼10 nm. The particles after the second set of irradiations also showed higher colloidal stability. SeNPs showed a dose-dependent antibacterial effect toward both standard and antibiotic-resistant phenotypes of Gram-negative and Gram-positive bacteria at a range of concentrations between 0.05 and 25 ppm. Besides, the SeNPs showed a low cytotoxic effect when cultured with human dermal fibroblasts cells at a range of concentrations up to 1 ppm while showing an anticancer effect toward human melanoma and glioblastoma cells at the same concentration range. This article therefore introduces the possibility of using totally naked SeNPs synthesized by a new PLAL protocol as a novel and efficient nanoparticle fabrication process for biomedical applications. Show less

Tradiditional physicochemical approaches for the synthesis of compounds, drugs, and nanostructures developed as potential solutions for antimicrobial resistance or against cancer treatment are, for the most part, facile and straightforward. Nevertheless, these approaches have several limitations, such as the use of toxic chemicals and production of toxic by-products with limited biocompatibility. Therefore, new methods are needed to address these limitations, and green chemistry offers a… Show more

Tradiditional physicochemical approaches for the synthesis of compounds, drugs, and nanostructures developed as potential solutions for antimicrobial resistance or against cancer treatment are, for the most part, facile and straightforward. Nevertheless, these approaches have several limitations, such as the use of toxic chemicals and production of toxic by-products with limited biocompatibility. Therefore, new methods are needed to address these limitations, and green chemistry offers a suitable and novel answer, with the safe and environmentally friendly design, manufacturing, and use of minimally toxic chemicals. Here, tellurium (Te) nanowires were synthesized using a novel green chemistry approach, and their structures and cytocompatibility were evaluated. This study suggests that green chemistry approaches for producing Te nanostructures may not only reduce adverse environmental effects resulting from traditional synthetic chemistry methods, but also be more effective in numerous health care applications. Show less

Bimetallic silver/gold nanosystems are expected to significantly improve therapeutic efficacy compared to their monometallic counterparts by maintaining the general biocompatibility of gold nanoparticles (AuNPs) while, at the same time, decreasing the relatively high toxicity of silver nanoparticles (AgNPs) toward healthy human cells. Thus, the aim of this research was to establish a highly reproducible one-pot green synthesis of colloidal AuNPs and bimetallic Ag/Au alloy nanoparticles (NPs;… Show more

Bimetallic silver/gold nanosystems are expected to significantly improve therapeutic efficacy compared to their monometallic counterparts by maintaining the general biocompatibility of gold nanoparticles (AuNPs) while, at the same time, decreasing the relatively high toxicity of silver nanoparticles (AgNPs) toward healthy human cells. Thus, the aim of this research was to establish a highly reproducible one-pot green synthesis of colloidal AuNPs and bimetallic Ag/Au alloy nanoparticles (NPs; Ag/AuNPs) using starch as reducing and capping agent. Show less

Bacterial infections and cancer are two of the most significant concerns that the current healthcare system should afford nowadays. Nanotechnology is presented as a solution. However, traditional nanoparticle synthesis methods involving chemical and physical approaches can be costly and potentially harm the environment due to the creation of toxic by-products as well as the use of harsh materials and conditions. Therefore, there is a growing need for the production of nanoparticles via green… Show more

Bacterial infections and cancer are two of the most significant concerns that the current healthcare system should afford nowadays. Nanotechnology is presented as a solution. However, traditional nanoparticle synthesis methods involving chemical and physical approaches can be costly and potentially harm the environment due to the creation of toxic by-products as well as the use of harsh materials and conditions. Therefore, there is a growing need for the production of nanoparticles via green chemical and eco-friendly methods. In the present article, citric juices (specifically, orange, lemon and lime) were used as reducing and capping agents for the bio synthesis of tellurium nanoparticles (labeled OR-TeNPs, LEM-TeNPs, LIM-TeNPs, respectively) of a uniform size distribution and rod- and cubic-shapes. The green-synthesized Te nanostructures showed antibacterial activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria, at concentrations from 5 to 50 µg/mL over a 24-hour time period, with slight differences depending on the raw material used. Nanoparticles were tested for their cytocompatibility with human dermal fibroblast (HDF) cells for 24 and 48 hours, showing no significant cytotoxic effect at concentrations up to 50 µg/mL. Moreover, the Te nanostructures were cultured with melanoma cancer cells inhibiting the average growth of cells within the same range of concentrations, with a similar trend of dose-inhibition dependence. Therefore, the synthesis of Te nanostructures using a green-synthesis approach with citric juices are proposed here as an alternative approach that overcomes the main limitations of traditional synthesis while showing desirable medical properties for fighting infection and cancer. Show less

Nanocolumnar titanium coatings have been fabricated in two sputtering systems with very different characteristics (a laboratory setup and semi-industrial equipment), thus possessing different morphologies (150 nm long columns tilted 20° from the normal and 300 nm long ones tilted 40°, respectively). These coatings exhibit similar antibacterial properties against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria. When a synergic route is followed and these… Show more

Nanocolumnar titanium coatings have been fabricated in two sputtering systems with very different characteristics (a laboratory setup and semi-industrial equipment), thus possessing different morphologies (150 nm long columns tilted 20° from the normal and 300 nm long ones tilted 40°, respectively). These coatings exhibit similar antibacterial properties against Gram positive (Staphylococcus aureus) and Gram negative (Escherichia coli) bacteria. When a synergic route is followed and these coatings are functionalized with tellurium (Te) nanorods, the antibacterial properties are enhanced, especially for the long nanocolumns case. The biocompatibility is preserved in all the nanostructured coatings. Show less

Antibiotic resistance is a predicament that affects more than 2 million people worldwide each year. Through the over-prescription and extensive use of antibiotics, bacteria have generated resistance to many common antibiotic treatments. A promising approach to target antibiotic-resistant bacteria is the use of metallic nanoparticles. In this work, an environmentally safe synthesis of tellurium nanoparticles was explored. Rod-shaped tellurium nanoparticles coated with polyvinylpyrrolidone (PVP)… Show more

Antibiotic resistance is a predicament that affects more than 2 million people worldwide each year. Through the over-prescription and extensive use of antibiotics, bacteria have generated resistance to many common antibiotic treatments. A promising approach to target antibiotic-resistant bacteria is the use of metallic nanoparticles. In this work, an environmentally safe synthesis of tellurium nanoparticles was explored. Rod-shaped tellurium nanoparticles coated with polyvinylpyrrolidone (PVP) were prepared using a facile hydrothermal reduction reaction. Transmission electron microscopy (TEM) images were used to characterize the size and morphology of the nanoparticles and showed a narrow size distribution. In addition, energy dispersive X-ray spectroscopy (EDS) was performed to verify the chemical composition of the nanoparticles. Antibacterial assays determined that treatment with nanoparticles at concentrations of 25 to 100 μg/mL induced a decay in the growth of both Gram-negative and Gram-positive bacteria—both antibiotic-resistant and non-antibiotic-resistance strains. To determine the effects of the nanoparticles on off-target cells, cytotoxicity assays were performed using human dermal fibroblasts (HDF) and melanoma (skin cancer) cells for durations of 24 and 48 h. Treatment with nanoparticles at concentrations between 10 and 100 μg/mL showed no significant cytotoxicity towards HDF cells. Contrarily, in melanoma cells, a cytotoxic effect was observed at the same concentrations. This suggests that the nanoparticles possess both anticancer properties towards melanoma cells and antibacterial effects without being toxic to healthy cells. These properties show that, for the first time, PVP-coated tellurium nanorods can be exploited for the treatment of antibiotic-resistant bacterial infections. These nanorods should be further explored for numerous antibacterial and anticancer applications. Show less

Antimicrobial resistance is a global concern that affects more than two million people each year. Therefore, new approaches to kill bacteria are needed. One of the most promising methodologies may come from metallic nanoparticles, since bacteria may not develop a resistance to these nanostructures as they do for antibiotics. While metallic nanoparticle synthesis methods have been well studied, they are often accompanied by significant drawbacks such as cost, extreme processing conditions, and… Show more

Antimicrobial resistance is a global concern that affects more than two million people each year. Therefore, new approaches to kill bacteria are needed. One of the most promising methodologies may come from metallic nanoparticles, since bacteria may not develop a resistance to these nanostructures as they do for antibiotics. While metallic nanoparticle synthesis methods have been well studied, they are often accompanied by significant drawbacks such as cost, extreme processing conditions, and toxic waste production since they use harsh chemicals such as corrosive agents (hydrazine) or strong acids (hydrochloride acid). In this work, we explored the environmentally safe synthesis of selenium nanoparticles, which have shown promise in killing bacteria. Using Escherichia coli, Pseudomonas aeruginosa, Methicillin-resistance Staphylococcus aureus, and S. aureus, 90-150 nm average diameter selenium nanoparticles were synthesized using an environmentally safe approach. Nanoparticles were characterized using transmission electron microscopy, energy dispersive X-ray spectroscopy to determine the chemical composition, and inductively coupled plasma mass spectrometry to validate chemistry. Nanoparticles were also characterized and tested for their ability to inhibit bacterial growth. A decay in bacterial growth after 24 h was achieved against both S. aureus and E. coli at biogenic selenium nanoparticle concentrations from 25 to 250 µg/mL and showed no significant cytotoxicity effect against human dermal fibroblasts for 24 h. Bacteria were able to synthesize selenium nanoparticles through the use of different functional structures within the organisms, mainly enzymes such as selenite reductases. Therefore, biogenic selenium nanoparticles made by bacteria represent a viable approach to reduce bacteria growth without antibiotics overcoming the drawbacks of synthetic methods that employ toxic chemicals. Show less