Fully　green　and　facile　redox　chemistry　involving　reduction　of　colloidal　iron　hydroxide　(Fe(OH)(3))　through　green　tea　(GT)　polyphenols　produced　water-soluble　Fe3O4　nanocrystals　coated　with　GT　extracts　namely　epigallocatechin　gallate　(EGCG)　and　epicatechin　(EC).　Electron　donating　polyphenols　stoichiometrically　reduced　Fe3+　ions　into　Fe2+　ions　resulting　in　the　formation　of　magnetite　(Fe3O4)　nanoparticles　and　corresponding　oxidized　products　(semiquinones　and　quinones)　that　simultaneously　served　as　efficient　surface　chelators　for　the　Fe3O4　nanoparticles　making　them　dispersible　and　stable　in　water,　PBS,　and　cell　culture　medium　for　extended　time　periods.　As-formed　iron　oxide　nanoparticles　(2.5-6　nm)　displayed　high　crystallinity　and　saturation　magnetization　as　well　as　high　relaxivity　ratios　manifested　in　strong　contrast　enhancement　observed　in　T-2-weighted　images.　Potential　of　green　tea-coated　superparamagnetic　iron　oxide　nanocrystals　(SPIONs)　as　superior　negative　contrast　agents　was　confirmed　by　in　vitro　and　in　vivo　experiments.　Primary　human　macrophages　(J774A.1)　and　colon　cancer　cells　(CT26)　were　chosen　to　assess　cytotoxicity　and　cellular　uptake　of　GT-,　EGCGq-,　and　ECq-coated　Fe3O4　nanoparticles,　which　showed　high　uptake　efficiencies　by　J774A.1　and　CT26　cells　without　any　additional　transfection　agent.　Furthermore,　the　in　vivo　accumulation　characteristics　of　GT-coated　Fe3O4　nanoparticles　were　similar　to　those　observed　in　clinical　studies　of　SPIONs　with　comparable　accumulation　in　epidermoid　cancer-xenograft　bearing　mice.　Given　their　promising　transport　and　uptake　characteristics　and　new　surface　chemistry,　GT-SPIONs　conjugates　can　be　applied　for　multimodal　imaging　and　therapeutic　applications　by　anchoring　further　functionalities.