This review tries to summarize the purpose of steadily developing surface-functionalized nanoparticles for various bio-applications and represents a fascinating and rapidly growing field of research. Due to their unique properties—such as novel optical, biodegradable, low-toxicity, biocompatibility, size, and highly catalytic features—these materials are considered superior, and it is thus vital to study these systems in a realistic and meaningful way. However, rapid aggregation, oxidation, and other problems are encountered with functionalized nanoparticles, inhibiting their subsequent utilization. Adequate surface modification of nanoparticles with organic and inorganic compounds results in improved physicochemical properties which can overcome these barriers. This review investigates and discusses the iron oxide nanoparticles, gold nanoparticles, platinum nanoparticles, silver nanoparticles, and silica-coated nanoparticles and how their unique properties after fabrication allow for their potential use in a wide range of bio-applications such as nano-based imaging, gene delivery, drug loading, and immunoassays. The different groups of nanoparticles and the advantages of surface functionalization and their applications are highlighted here. In recent years, surface-functionalized nanoparticles have become important materials for a broad range of bio-applications.

Ophthalmic drug bioavailability is limited due to protective mechanisms of the eye which require the design of a system to enhance ocular delivery. In this study several liposomal formulations containing ciprofloxacin (CPX) have been formulated using reverse phase evaporation technique with final dispersion of pH 7.4. Different types of phospholipids including Phosphatidylcholine, Dipalmitoylphosphatidylcholine and Dimyristoyl-sn-glycero-3-phosphocholine were utilized. The effect of formulation factors such as type of phospholipid, cholesterol content, incorporation of positively charging inducing agents and ultrasonication on the properties of the liposomal vesicles was studied. Bioavailability of selected liposomal formulations in rabbit eye aqueous humor has been investigated and compared with that of commercially available CPX eye drops (Ciprocin®). Pharmacokinetic parameters including Cmax, Tmax, elimination rate constant, t1/2, MRT and AUC0-∞, were determined. The investigated formulations showed more than three folds of improvement in CPX ocular bioavailability compared with the commercial product.

Rheumatoid arthritis (RA) is a systemic, chronic autoimmune disease that causes disability due to progressive inflammation and destruction of the tissues around the joints. Methotrexate is mainly used to prevent the progression of joint destruction and reduce the deformity. The major challenge in treating RA with methotrexate is the systemic side effects that limit dose escalation. Hence, a novel formulation of a methotrexate-loaded nanoemulsion for subcutaneous administration was developed that aims to deliver methotrexate into the system via the lymph. The methotrexate-loaded nanoemulsion was prepared by using the aqueous-titration method. The prepared nanoemulsion was investigated for particle size, surface charge, surface morphology, entrapment efficiency, DSC (differential scanning colorimetry), drug release, hemocompatibility assay, and cytotoxicity, as well as anti-arthritic and stability studies. The vesicle size, zeta potential, PDI (polydispersity index), and entrapment efficiency of the optimized nanoemulsion were 87.89 ± 2.86 nm, 35.9 ± 0.73 mV, 0.27, and 87 ± 0.25%, respectively. The DSC study showed that the crystalline methotrexate was converted to an amorphous form and the drug was fully incorporated into the vesicles. After 72 h, the optimized nanoemulsion showed a drug release of 96.77 ± 0.63%, indicating a sustained-release dosage form. Cytocompatibility testing by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay on macrophage cell lines showed that the nanoemulsion was non-toxic. The formulation showed significant anti-arthritic activity compared to the marketed drug solution. In addition, the nanoemulsion containing methotrexate remained stable for three months when stored at a low temperature. Since the nanoemulsion containing methotrexate has excellent physicochemical properties and lowers systemic side effects by targeted delivery, it is a desirable technology for subcutaneous drug delivery.

Bromocriptine mesylate (BM), primarily ergocryptine, is a dopamine agonist derived from ergot alkaloids. This study aimed to formulate chitosan (CS)-coated poly ε-caprolactone nanoparticles (PCL NPs) loaded with BM for direct targeting to the brain via the nasal route. PCL NPs were optimized using response surface methodology and a Box–Behnken factorial design. Independent formulation parameters for nanoparticle attributes, including PCL payload (A), D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) concentration (B), and sonication time (C), were investigated. The dependent variables were nanoparticle size (Y1), zeta potential (Y2), entrapment efficiency (EE; Y3), and drug release rate (Y4). The optimal formulation for BM-PCL NPs was determined to be 50 mg PCL load, 0.0865% TPGS concentration, and 8 min sonication time, resulting in nanoparticles with a size of 296 ± 2.9 nm having a zeta potential of −16.2 ± 3.8 mV, an EE of 90.7 ± 1.9%, and a zero-order release rate of 2.6 ± 1.3%/min. The optimized BM-PCL NPs were then coated with CS at varying concentrations (0.25, 0.5, and 1%) to enhance their effect. The CS-PCL NPs exhibited different particle sizes and zeta potentials depending on the CS concentration used. The highest EE (88%) and drug load (DL; 5.5%) were observed for the optimized BM-CS-PCL NPs coated with 0.25% CS. The BM-CS-PCL NPs displayed a biphasic release pattern, with an initial rapid drug release lasting for 2 h, followed by a sustained release for up to 48 h. The 0.25% CS-coated BM-CS-PCL NPs showed a high level of permeation across the goat nasal mucosa, with reasonable mucoadhesive strength. These findings suggested that the optimized 0.25% CS-coated BM-CS-PCL NPs hold promise for successful nasal delivery, thereby improving the therapeutic efficacy of BM.

Conjunctivitis and endogenous bacterial endophthalmitis mostly occurred after ophthalmic surgery. Therefore, the present study aimed to maximize the ocular delivery of ciprofloxacin (CPX) using colloidal lipid-based carrier to control the post-surgical infection. In this study, CPX was formulated as ophthalmic liposomal drops. Two different phospholipids in different ratios were utilized, including phosphatidylcholine (PC) and dimyrestoyl phosphatidylcholine (DMPC). The physiochemical properties of the prepared ophthalmic liposomes were evaluated in terms of particle size, entrapment efficiency, polydispersity index, zeta potential, and cumulative CPX in-vitro release. In addition, the effect of sonication time on particle size and entrapment efficiency of CPX ophthalmic drops was also evaluated. The results revealed that most of the prepared formulations showed particle size in nanometer size range (460–1047 nm) and entrapment efficiency ranging from 36.4–44.7%. The antibacterial activity and minimum inhibitory concentration (MIC) were investigated. Ex vivo antimicrobial effect of promising formulations was carried out against the most common causes of endophthalmitis microorganisms. The pharmacokinetics of the prepared ophthalmic drops were tested in rabbit aqueous humor and compared with commercial CPX ophthalmic drops (Ciloxan^®). Observed bacterial suppression was detected in rabbit’s eyes conjunctivitis with an optimized formulation A3 compared with the commercial ophthalmic drops. CPX concentration in the aqueous humor was above MIC against tested bacterial strains. The in vivo data revealed that the tested CPX drops showed superiority over the commercial ones with respect to peak aqueous humor concentration, time to reach peak aqueous humor concentration, elimination rate constant, half-life, and relative bioavailability. Based on these results, it was concluded that the prepared ophthalmic formulations significantly enhanced CPX bioavailability compared with the commercial one.

Acyclovir has a short half-life and offers poor bioavailability. Its daily dose is 200 mg five times a day. A tamarind gum and β-cyclodextrin-based pH-responsive hydrogel network for sustained delivery of acyclovir was developed using the free-radical polymerization technique. Developed networks were characterized by FTIR, DSC, TGA, PXRD, EDX, and SEM. The effect of varying feed ratios of polymers, monomers, and crosslinker on the gel fraction, swelling, and release was also investigated. FTIR findings confirmed the compatibility of the ingredients in a new complex polymer. The thermal stability of acyclovir was increased within the newly synthesized polymer. SEM photomicrographs confirmed the porous texture of hydrogels. The gel fraction was improved (from 90.12% to 98.12%) with increased reactant concentrations. The pH of the dissolution medium and the reactant contents affected swelling dynamics and acyclovir release from the developed carrier system. Based on the R2 value, the best-fit model was zero-order kinetics with non-Fickian diffusion as a release mechanism. The biocompatibility of the developed network was confirmed through hematology, LFT, RFT, lipid profile, and histopathological examinations. No sign of pathology, necrosis, or abrasion was observed. Thus, a pH-responsive and biocompatible polymeric system was developed for sustained delivery of acyclovir to reduce the dosing frequency and improve patient compliance.